x86,fs/resctrl: Support AMD Assignable Bandwidth Monitoring Counters (ABMC)

This series adds the support for Assignable Bandwidth Monitoring Counters (ABMC). It is also called QoS RMID Pinning feature.

Series is written such that it is easier to support other assignable features supported from different vendors.

The feature details are documented in the APM listed below [1].
[1] AMD64 Architecture Programmer's Manual Volume 2: System Programming Publication # 24593 Revision 3.41 section 19.3.3.3 Assignable Bandwidth Monitoring (ABMC). The documentation is available at

The patches are based on top of commit (6.16.0-rc7) commit 34481698fd9c ("Merge branch into tip/master: 'x86/sev'")

# Introduction

Users can create as many monitor groups as RMIDs supported by the hardware. However, the bandwidth monitoring feature on AMD systems only guarantees that RMIDs currently assigned to a processor will be tracked by hardware. The counters of any other RMIDs which are no longer being tracked will be reset to zero. The MBM event counters return "Unavailable" for the RMIDs that are not tracked by hardware. So, there can be only limited number of groups that can give guaranteed monitoring numbers. With ever changing configurations there is no way to definitely know which of these groups are being tracked during a particular time. Users do not have the option to monitor a group or set of groups for a certain period of time without worrying about counters being reset in between.

The ABMC feature allows users to assign a hardware counter ID to an RMID, event pair and monitor bandwidth usage as long as it is assigned. The hardware continues to track the assigned counter until it is explicitly unassigned by the user. Additionally, the user can specify the type of memory transactions (e.g., reads, writes) to be tracked by the counter for the assigned RMID.

Without ABMC enabled, monitoring will work in current 'default' mode without assignment option.

# History

Earlier implementation of ABMC had dependancy on BMEC (Bandwidth Monitoring Event Configuration). Peter had concerns with that implementation because it may be not be compatible with ARM's MPAM.

Here are the threads discussing the concerns and new interface to address the concerns.
https://lore.kernel.org/lkml/CALPaoCg97cLVVAcacnarp+880xjsedEWGJPXhYpy4P7=ky4MZw@mail.gmail.com/
https://lore.kernel.org/lkml/CALPaoCiii0vXOF06mfV=kVLBzhfNo0SFqt4kQGwGSGVUqvr2Dg@mail.gmail.com/

Here are the finalized requirements based on the discussion:

* BMEC and ABMC are incompatible with each other. They need to be mutually exclusive.

* Eliminate global assignment listing. The interface
/sys/fs/resctrl/info/L3_MON/mbm_assign_control is no longer required.

* Create the configuration directories at /sys/fs/resctrl/info/L3_MON/counter_configs/.
The configuration file names should be free-form, allowing users to create them as needed.

* Perform assignment listing at the group level by introducing mbm_L3_assignments
in each monitoring group level. The listing should provide the following details:

Event Configuration: Specifies the event configuration applied. This will be crucial when "mkdir" on event configuration is added in the future, leading to the creation of mon_data/mon_l3_*/<event configuration>.

Domains: Identifies the domains where the configuration is applied, supporting multi-domain setups.

Assignment Type: Indicates whether the assignment is Exclusive (e or d), Shared (s), or Unassigned (_).

Exclusive assignment: Assign the counter ID the RMID, event pair exclusively.

Shared assignment: A shared assignment applies to both soft-ABMC and ABMC. A user can designate a
"counter" (could be hardware counter or "active" RMID) as shared and that means the counter within that domain is shared between different monitor groups and actual assignment is scheduled by resctrl.

Unassigned: No longer assigned.

* Provide option to enable or disable auto assignment when new group is created.

* Keep the flexibility to support future assign options like Soft-ABMC etc.

    https://lore.kernel.org/lkml/[email protected]/

This series addresses the requirements listed above and keeping the options open for future enhancements.

# Implementation details

Create a generic interface to support user space assignment of scarce counters used for monitoring. First usage of interface is by ABMC with option to expand usage to "soft-ABMC" and MPAM counters in future.

Feature adds following interface files:

/sys/fs/resctrl/info/L3_MON/mbm_assign_mode: Reports the list of assignable monitoring features supported. The enclosed brackets indicate which feature is enabled.

/sys/fs/resctrl/info/L3_MON/num_mbm_cntrs: The maximum number of monitoring counters (total of available and assigned counters) in each domain when the system supports mbm_event mode.

/sys/fs/resctrl/info/L3_MON/available_mbm_cntrs: The number of monitoring counters available for assignment in each domain when mbm_event mode is enabled on the system.

/sys/fs/resctrl/info/L3_MON/event_configs: Contains sub-directory for each MBM event
that can be assigned to a counter.

/sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter: The type of
memory transactions tracked by the event mbm_total_bytes.

/sys/fs/resctrl/info/L3_MON/event_configs/mbm_local_bytes/event_filter: The type of
memory transactions tracked by the event mbm_local_bytes.

/sys/fs/resctrl/mbm_L3_assignments: Per monitor group interface to list or modify
counters assigned to the group.

# Examples

a. Check if MBM assign support is available
#mount -t resctrl resctrl /sys/fs/resctrl/

# cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode [mbm_event]
default

mbm_event feature is detected and it is enabled.

b. Check how many assignable counters are supported.

	# cat /sys/fs/resctrl/info/L3_MON/num_mbm_cntrs 
	0=32;1=32

c. Check how many assignable counters are available for assignment in each domain.

	# cat /sys/fs/resctrl/info/L3_MON/available_mbm_cntrs 
	0=30;1=30

d. Check the default event configuration.

	# cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter 
	local_reads,remote_reads,local_non_temporal_writes,remote_non_temporal_writes,
        local_reads_slow_memory,remote_reads_slow_memory,dirty_victim_writes_all

	# cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_local_bytes/event_filter 
	local_reads,local_non_temporal_writes,local_reads_slow_memory

e. Series adds a new interface file "mbm_L3_assignments" in each monitoring group
to list and modify that group's monitoring states.

The list is displayed in the following format:

<Event>:<Domain id>=<Assignment state>;<Domain id>=<Assignment state>

Event: A valid MBM event listed in the /sys/fs/resctrl/info/L3_MON/event_configs directory.

Domain ID: A valid domain ID.

Assignment types:

_ : No counter assigned.

e : Counter assigned exclusively.

To list the default group states:
# cat /sys/fs/resctrl/mbm_L3_assignments
mbm_total_bytes:0=e;1=e
mbm_local_bytes:0=e;1=e

To unassign the counter associated with the mbm_total_bytes event on domain 0:
# echo "mbm_total_bytes:0=_" > /sys/fs/resctrl/mbm_L3_assignments # cat /sys/fs/resctrl/mbm_L3_assignments
mbm_total_bytes:0=_;1=e
mbm_local_bytes:0=e;1=e

To unassign the counter associated with the mbm_total_bytes event on all domains:
# echo "mbm_total_bytes:*=_" > /sys/fs/resctrl/mbm_L3_assignments
# cat /sys/fs/resctrl/mbm_L3_assignment
mbm_total_bytes:0=_;1=_
mbm_local_bytes:0=e;1=e

To assign a counter associated with the mbm_total_bytes event on all domains in exclusive mode:
# echo "mbm_total_bytes:*=e" > /sys/fs/resctrl/mbm_L3_assignments
# cat /sys/fs/resctrl/mbm_L3_assignments
mbm_total_bytes:0=e;1=e
mbm_local_bytes:0=e;1=e

g. Read the events mbm_total_bytes and mbm_local_bytes of the default group.
There is no change in reading the events with the assignment. If the event is unassigned when reading, then the read will come back as "Unassigned".

	# cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_total_bytes
	779247936
	# cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes 
	765207488

h. Check the event configurations.

	# cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter
	local_reads,remote_reads,local_non_temporal_writes,remote_non_temporal_writes,
	local_reads_slow_memory,remote_reads_slow_memory,dirty_victim_writes_all

	# cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_local_bytes/event_filter
	local_reads,local_non_temporal_writes,local_reads_slow_memory

i. Change the event configuration for mbm_local_bytes.

	# echo "local_reads, local_non_temporal_writes, local_reads_slow_memory, remote_reads" >
	/sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes/event_filter

	# cat /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes/event_filter
	local_reads,local_non_temporal_writes,local_reads_slow_memory,remote_reads

This will update all (across all domains of all monitor groups) counter assignments associated with the mbm_local_bytes event.

j. Now read the local event again. The first read may come back with "Unavailable"
status. The subsequent read of mbm_local_bytes will display the current value.

	# cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes
	Unavailable
	# cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes
	314101

k. Users have the option to go back to 'default' mbm_assign_mode if required.
This can be done using the following command. Note that switching the mbm_assign_mode will reset all the MBM counters (and thus all MBM events) of all the resctrl groups.

	# echo "default" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
	# cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
	mbm_event
	[default]

l. Unmount the resctrl filesystem.

	# umount /sys/fs/resctrl/
---
v16:
    Picked up first four patches from (Tony):
    https://lore.kernel.org/lkml/[email protected]/
    These patches have already been reviewed.

Updated Reviewed-by: tag for few patches.

Fixed the conflicts with latest cpufeatures.h and scattered.c files.

Added a new check in get_rdt_mon_resources().
Added check in resctrl_is_mon_event_enabled() before enabling.

Resetting the architectural state in resctrl_arch_config_cntr() in both assign and unassign cases now.

Function renames:
resctrl_config_cntr() -> rdtgroup_assign_cntr() rdtgroup_alloc_config_cntr() -> rdtgroup_alloc_assign_cntr()

Passed struct mevt to rdtgroup_alloc_assign_cntr so it can print event name on failure.

Function rename:
rdtgroup_free_config_cntr() -> rdtgroup_free_unassign_cntr().

Updated rdtgroup_free_unassign_cntr() to pass struct mon_evt to match rdtgroup_alloc_assign_cntr() prototype.

Removed lots of copied and unnecessary text from resctrl.h. Also removed references to LLC occupancy.
Removed arch_mon_ctx from resctrl_arch_cntr_read().

Renamed get_corrected_val() -> get_corrected_val().

Removed the call resctrl_arch_rmid_read_context_check(); Added the text about RMID_VAL_UNAVAIL error.

Squashed two patches into one.
https://lore.kernel.org/lkml/df215f02db88cad714755cd5275f20cf0ee4ae26.1752013061.git.babu.moger@amd.com/
https://lore.kernel.org/lkml/296c435e9bf63fc5031114cced00fbb4837ad327.1752013061.git.babu.moger@amd.com/

Changed is_cntr field in struct rmid_read to is_mbm_cntr. Fixed the memory leak with arch_mon_ctx. Updated the resctrl.rst user doc.

Report Unassigned only if none of the events in CTRL_MON and MON are assigned.

Moved event_filter_show() to fs/resctrl/monitor.c

Added rdtgroup_mutex in event_filter_show(). Removed extern for mbm_transactions. Not required.

Moved resctrl_process_configs() and event_filter_write() to fs/resctrl/monitor.c.

Renamed resctrl_process_configs() -> resctrl_parse_mem_transactions().

Fixed the return in resctrl_mbm_assign_on_mkdir_write().

Moved r->mon.mbm_assign_on_mkdir initialization to resctrl_mon_resource_init().

Updated resctrl.rst few corrections and consistancy.

Fixed few references of counter_configs to -> event_configs.
Renamed resctrl_process_assign() to resctrl_parse_mbm_assignment(). Moved resctrl_parse_mbm_assignment() and rdtgroup_modify_assign_state() to monitor.c.

Added new comment in resctrl_bmec_files_show() about kernfs_find_and_get failure. Added the parameter to resctrl_bmec_files_show() to pass the kernfs_node. Updated resctrl_bmec_files_show() to pass NULL for kn_fs_node.

Added a patch to add me as a reviewer on Reinette's suggestion.

v15:
1-4 Picked up Tony's tree. This will be base for both the series. rdt-aet-v5.5 branch of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux.git
After Reinette's comment on previous version.
https://lore.kernel.org/lkml/[email protected]/
https://lore.kernel.org/lkml/[email protected]/

Improved changelog in most of the patches. Thanks to Reinette. Improved the code comment in few places.

Fixed the enumeration code by adding check in resctrl_cpu_detect() during the init. Moved the fs related enumeration to resctrl_mon_resource_init().

Removed evt_cfg from struct mbm_cntr_cfg based on the discussion.
https://lore.kernel.org/lkml/[email protected]/

Removed resctrl_set_mon_evt_cfg().
Moved the event initialization to resctrl_mon_resource_init().

Changed few goto labels for consistency.

Added extra check !r->mon.mbm_cntr_assignable in mbm_cntr_get() to return error.

Added two new arch calls resctrl_arch_cntr_read() and resctrl_arch_reset_cntr() implement mbm_event mode. This is kind of major change in this series.
https://lore.kernel.org/lkml/[email protected]/

Added is_cntr in rmid_read to implement resctrl_arch_cntr_read() and resctrl_arch_reset_cntr().

Removed the error setting in rdtgroup_mondata_show(). It is already done in mon_event_read() based on the discussion.
https://lore.kernel.org/lkml/[email protected]/

Changed the function name resctrl_mkdir_counter_configs() to resctrl_mkdir_event_configs(). Called resctrl_mkdir_event_configs from rdtgroup_mkdir_info_resdir().
It avoids the call kernfs_find_and_get() to get the node for info directory. Used for_each_mon_event() where applicable.

Fixed the partial initialization of val in resctrl_process_configs().
Passed mon_evt where applicable. The struct rdt_resource can be obtained from mon_evt::rid.

Fixed the static checker warning in resctrl_mbm_assign_on_mkdir_write() reported in
https://lore.kernel.org/lkml/[email protected]/

Moved resctrl_bmec_files_show() inside rdtgroup_mkdir_info_resdir().

v14:
Patch #1 is already been reviewed. Not need to review.

Patches # 2-5:
This is Tony's work. This is part of Tony's telemetry series.
https://lore.kernel.org/lkml/[email protected]/

Tony made special update for me to include in this series.
https://lore.kernel.org/lkml/[email protected]/.
We both are going to carry thesse mutliple events support patches.

Patches #6-31 are changes related to mbm_assign_mode.

Took time to check all the text comments. Taken care most of comments. Anything missing is not intentional. ):

Removed the dependancy on X86_FEATURE_CQM_MBM_TOTAL and X86_FEATURE_CQM_MBM_LOCAL as discussed in https://lore.kernel.org/lkml/[email protected]/
Reworked on ABMC enumeration during the init.

Updated the code comment in resctrl.h on all the prototypes.

Added lockdep_assert_cpus_held() in _resctrl_abmc_enable(). Removed inline for resctrl_arch_mbm_cntr_assign_enabled(). Added prototype descriptions for resctrl_arch_mbm_cntr_assign_enabled() and resctrl_arch_mbm_cntr_assign_set() in include/linux/resctrl.h.

Changed the name of the monitor mode to mbm_event_assign based on the discussion.
https://lore.kernel.org/lkml/[email protected]/
Updated resctrl.rst for mbm_event mode.
Changed subject line to fs/resctrl in few patches.

Removed BMEC reference internal.h.

Removed mbm_mode in mon_evt data structure as it is not required anymore. Added resctrl_get_mon_evt_cfg() and resctrl_set_mon_evt_cfg().

Removed evt_cfg parameter in resctrl_arch_config_cntr(). Get evt_cfg only when assign is required.

Updated the code documentation for mbm_cntr_alloc() and mbm_cntr_get(). Passed struct mon_evt to resctrl_assign_cntr_event() that way to avoid back and forth calls to get event details.

Passing the struct mon_evt to resctrl_free_config_cntr() and removed the need for mbm_get_mon_event() call.
Corrected the code documentation for mbm_cntr_free().

Added WARN_ON_ONCE() when cntr_id < 0.
Improved code documentation in include/linux/resctrl.h.
Added the check in mbm_update() to skip overflow handler when counter is unassigned.

Changed the term memory events to memory transactions to be consistant.

Changed the name of directory to event_configs from counter_config. Updated user doc about the memory transactions supported by assignment.

Renamed few functions resctrl_group_assign() -> rdtgroup_assign_cntr() resctrl_update_assign() -> resctrl_assign_cntr_allrdtgrp()

Added rdtgroup_mutex in resctrl_mbm_assign_on_mkdir_show().

Fixed the problem reported by Peter.
https://lore.kernel.org/lkml/CALPaoCjvUSKLKOXzF85j8mHT=eZYM-7R0=gJ3PRgOk4yuF5ZhQ@mail.gmail.com/
Updated the changelog.

Added check in rdt_mon_features_show to hide bmec related feature.

Added the call resctrl_bmec_files_show() to enable/disable files related to BMEC monitor mode is changed.

Added resctrl_set_mon_evt_cfg() to reset event configuration values when mode is changes.

Changed the name of the mbm_assign_mode's supported to mbm_event or default.
https://lore.kernel.org/lkml/[email protected]/

Added example section in user doc (resctrl.rst) on how to use mbm_assign_modes.

v13:
Removed BMEC related 2 patches which were in the previous series. It was related to optimization which can be doen later.

Patches are created on top of FS/ARCH restructure. So, major changes are due to FS/ARCH restructure. The files are split between arch/x86/kernel/cpu/resctrl/ and fs/resctrl/. So, functions are moved between these files accordingly.

Added fflag RFTYPE_RES_CACHE for mbm_assign_mode, num_mbm_cntrs, available_mbm_cntrs.

Removed the references to "mbm_assign_control".

Moved resctrl_arch_config_cntr() prototype to include/linux/resctrl.h. Changed resctrl_arch_config_cntr() to retun void from int to simplify few call sequences.

Added the event configuration details inside the evt_list in monitor domains. The avoids the need for new structure mbm_assign_config.

Passed evtid to functions resctrl_alloc_config_cntr() and resctrl_assign_cntr_event(). Event configuration value can be easily obtained from mon_evt list.

Added new patch to pass the entire struct rdtgroup to __mon_event_count(), mbm_update(), and related functions. We can easily get RMID,CLOSID etc from rdtgroup.

Added new function __cntr_id_read_phys() to handle ABMC event reading.

Added a new patch to hide BMEC related files when mbm_cntr_assign mode is enabled..

Added the call resctrl_init_evt_configuration() to setup the event configuration during init.

And few other commit message updates and user doc updates.

Removed Reviewed-by from few patches as patches have changed due to FS/ARCH restructure.

Let me know if I missed something.

v12:
This version is kind of RFC series with a new interface.

Removed Reviewed-by tag on few patches when the patch has changed.

Moved BMEC related patches (1 and 2) to beginning of the series. Removed the dependancy on BMEC to ABMC feature.

Removed the un-necessary initialization of mon_config_info structure. Changed wrmsrl instead of wrmsr to address the below comment.
https://lore.kernel.org/lkml/[email protected]/

Fixed the conflicts due to recent changes in rdt_resource data structure. Added new mbm_cfg_mask field to resctrl_mon.

Added the code to reset arch state inside _resctrl_abmc_enable().

Added the check CONFIG_RESCTRL_ASSIGN_FIXED to take care of arm platforms. This will be defined only in arm and not in x86.

Changed the code to display the max supported monitoring counters in each domain.

Fixed the struct mbm_cntr_cfg code documentation.
Moved the struct mbm_cntr_cfg definition to resctrl/internal.h as suggested by James.

Replaced seq_puts(s, ";") with seq_putc(s, ';');
Added missing rdt_last_cmd_clear() in resctrl_available_mbm_cntrs_show().

Added the check to reset the architecture-specific state only when assign is requested.

Added evt_cfg as the parameter to resctrl_arch_config_cntr() as the user will be passing the event configuration from /info/L3_MON/event_configs/.

Changed the check in resctrl_alloc_config_cntr() to reduce the indentation.
Fixed the handling error on first failure while assigning.
Added new parameter event configuration (evt_cfg) to get the event configuration from user space.

Added tte support for reading ABMC counters. This is bit involved change and affects lots of code.

New patch to support event configurations via new counter_configs method.

Removed mbm_cntr_reset() as it is not required while removing the group.

Added new patch to handle auto assign on group creation ("mbm_assign_on_mkdir")

Added couple of patches add interface for "mbm_L3_assignments" on each mon group.

Introduced mbm_cntr_free_all() and resctrl_reset_rmid_all() to clear counters and non-architectural states when monitor mode is changed.
https://lore.kernel.org/lkml/[email protected]/

Moved the resctrl_arch_mbm_cntr_assign_set_one to domain_add_cpu_mon().

Patches 17, 18, 19, 20, 21, 23, 24 are completely new to address the new interface requirement.

v11:
The commit 2937f9c361f7a ("x86/resctrl: Introduce resctrl_file_fflags_init() to initialize fflags") is already merged. Removed from the series.

Resolved minor conflicts due to code displacement in latest code.

Moved the monitoring related calls to monitor.c file when possible.
Moved some of the changes from include/linux/resctrl.h to arch/x86/kernel/cpu/resctrl/internal.h as requested by Reinette. This changes will be moved back when arch and non code is separated.

Renamed rdtgroup_mbm_assign_mode_show() to resctrl_mbm_assign_mode_show(). Renamed rdtgroup_num_mbm_cntrs_show() to resctrl_num_mbm_cntrs_show().

Moved the mon_config_info structure definition to internal.h.
Moved resctrl_arch_mon_event_config_get() and resctrl_arch_mon_event_config_set() to monitor.c file.

Moved resctrl_arch_assign_cntr() and resctrl_abmc_config_one_amd() to monitor.c. Added the code to reset the arch state in resctrl_arch_assign_cntr().
Also removed resctrl_arch_reset_rmid() inside IPI as the counters are reset from the callers.

Renamed rdtgroup_assign_cntr_event() to resctrl_assign_cntr_event(). Refactored the resctrl_assign_cntr_event().
Added functionality to exit on the first error during assignment. Simplified mbm_cntr_free().
Removed the function mbm_cntr_assigned(). Will be using mbm_cntr_get() to figure out if the counter is assigned or not.

Renamed rdtgroup_unassign_cntr_event() to resctrl_unassign_cntr_event(). Refactored the resctrl_unassign_cntr_event().

Moved mbm_cntr_reset() to monitor.c.
Added code reset non-architectural state in mbm_cntr_reset(). Added missing rdtgroup_unassign_cntrs() calls on failure path.

Domain can be NULL with SNC support so moved the unassign check in rdtgroup_mondata_show().

Renamed rdtgroup_mbm_assign_mode_write() to resctrl_mbm_assign_mode_write(). Added more details in resctrl.rst about mbm_cntr_assign mode. Re-arranged the text in resctrl.rst file in section mbm_cntr_assign.

Moved resctrl_arch_mbm_cntr_assign_set_one() to monitor.c

Added non-arch RMID reset in mbm_config_write_domain().
Removed resctrl_arch_reset_rmid() call in resctrl_abmc_config_one_amd(). Not required as reset of arch and non-arch rmid counters done from the callers. It simplies the IPI code.

Fixed printing the separator after each domain while listing the group assignments. Renamed rdtgroup_mbm_assign_control_show to resctrl_mbm_assign_control_show().

Fixed the static check warning with initializing dom_id in resctrl_process_flags()

Added change log in each patch for specific changes.

v10:
Major change is related to domain specific assignment.
Added struct mbm_cntr_cfg inside mon domains. This will handle
the domain specific assignments as discussed in below.
https://lore.kernel.org/lkml/CALPaoCj+zWq1vkHVbXYP0znJbe6Ke3PXPWjtri5AFgD9cQDCUg@mail.gmail.com/
I did not see the need to add cntr_id in mbm_state structure. Not used in the code. Following patches take care of these changes.
Patch 12, 13, 15, 16, 17, 18.

Added __init attribute to cache_alloc_hsw_probe(). Followed function prototype rules (preferred order is storage class before return type).

Moved the mon_config_info structure definition to resctrl.h

Added call resctrl_arch_reset_rmid() to reset the RMID in the domain inside IPI call resctrl_abmc_config_one_amd.

SMP and non-SMP call support is not required in resctrl_arch_config_cntr with new domain specific assign approach/data structure.

Assigned the counter before exposing the event files.
Moved the call rdtgroup_assign_cntrs() inside mkdir_rdt_prepare_rmid_alloc(). This is called both CNTR_MON and MON group creation.

Call mbm_cntr_reset() when unmounted to clear all the assignments.

Fixed the issue with finding the domain in multiple iterations in rdtgroup_process_flags().

Printed full error message with domain information when assign fails.

Taken care of other text comments in all the patches. Patch specific changes are in each patch.

If I missed something please point me and it is not intentional.

v9:
Patch 14 is a new addition.
Major change in patch 24.
Moved the fix patch to address __init attribute to begining of the series. Fixed all the call sequences. Added additional Fixed tags.

Added Reviewed-by where applicable.

Took care of couple of minor merge conflicts with latest code. Re-ordered the MSR in couple of instances.
Added available_mbm_cntrs (patch 14) to print the number of counter in a domain.

Used MBM_EVENT_ARRAY_INDEX macro to get the event index. Introduced rdtgroup_cntr_id_init() to initialize the cntr_id

Introduced new function resctrl_config_cntr to assign the counter, update the bitmap and reset the architectural state.
Taken care of error handling(freeing the counter) when assignment fails.

Changed rdtgroup_assign_cntrs() and rdtgroup_unassign_cntrs() to return void. Updated couple of rdtgroup_unassign_cntrs() calls properly.

Fixed problem changing the mode to mbm_cntr_assign mode when it is not supported. Added extra checks to detect if systems supports it.

https://lore.kernel.org/lkml/[email protected]/
As discussed in the above comment, introduced resctrl_mon_event_config_set to handle IPI. But sending another IPI inside IPI causes problem. Kernel reports SMP warning. So, introduced resctrl_arch_update_cntr() to send the command directly.

Fixed handling special case '//0=' and '//".
Removed extra strstr() call in rdtgroup_mbm_assign_control_write(). Added generic failure text when assignment operation fails. Corrected user documentation format texts.

v8:
Patches are getting into final stages.
Couple of changes Patch 8, Patch 19 and Patch 23.
Most of the other changes are related to rename and text message updates.

Details are in each patch. Here is the summary.

Added __init attribute to dom_data_init() in patch 8/25. Moved the mbm_cntrs_init() and mbm_cntrs_exit() functionality inside dom_data_init() and dom_data_exit() respectively.

Renamed resctrl_mbm_evt_config_init() to arch_mbm_evt_config_init() Renamed resctrl_arch_event_config_get() to resctrl_arch_mon_event_config_get().
resctrl_arch_event_config_set() to resctrl_arch_mon_event_config_set().

Rename resctrl_arch_assign_cntr to resctrl_arch_config_cntr. Renamed rdtgroup_assign_cntr() to rdtgroup_assign_cntr_event(). Added the code to return the error if rdtgroup_assign_cntr_event fails. Moved definition of MBM_EVENT_ARRAY_INDEX to resctrl/internal.h. Renamed rdtgroup_mbm_cntr_is_assigned to mbm_cntr_assigned_to_domain Added return error handling in resctrl_arch_config_cntr(). Renamed rdtgroup_assign_grp to rdtgroup_assign_cntrs.
Renamed rdtgroup_unassign_grp to rdtgroup_unassign_cntrs. Fixed the problem with unassigning the child MON groups of CTRL_MON group. Reset the internal counters after mbm_cntr_assign mode is changed. Renamed rdtgroup_mbm_cntr_reset() to mbm_cntr_reset()
Renamed resctrl_arch_mbm_cntr_assign_configure to
resctrl_arch_mbm_cntr_assign_set_one.

Used the same IPI as event update to modify the assignment. Could not do the way we discussed in the thread.
https://lore.kernel.org/lkml/[email protected]/
Needed to figure out event type to update the configuration.

Moved unassign first and assign during the assign modification. Assign none "_" takes priority. Cannot be mixed with other flags. Updated the documentation and .rst file format. htmldoc looks ok.

v7:
Major changes are related to FS and arch codes separation. Changed few interface names based on feedback.
Here are the summary and each patch contains changes specific the patch.

Removed WARN_ON for num_mbm_cntrs. Decided to dynamically allocate the bitmap. WARN_ON is not required anymore.

Renamed the function resctrl_arch_get_abmc_enabled() to resctrl_arch_mbm_cntr_assign_enabled().

Merged resctrl_arch_mbm_cntr_assign_disable, resctrl_arch_mbm_cntr_assign_disable and renamed to resctrl_arch_mbm_cntr_assign_set(). Passed the struct rdt_resource to these functions.

Removed resctrl_arch_reset_rmid_all() from arch code. This will be done from FS the caller.

Updated the descriptions/commit log in resctrl.rst to generic text. Removed ABMC references. Renamed mbm_mode to mbm_assign_mode.
Renamed mbm_control to mbm_assign_control.
Introduced mutex lock in rdtgroup_mbm_mode_show().

The 'legacy' mode is called 'default' mode.

Removed the static allocation and now allocating bitmap mbm_cntr_free_map dynamically.

Merged rdtgroup_assign_cntr(), rdtgroup_alloc_cntr() into one. Merged rdtgroup_unassign_cntr(), rdtgroup_free_cntr() into one.

Added struct rdt_resource to the interface functions resctrl_arch_assign_cntr () and resctrl_arch_unassign_cntr().
Rename rdtgroup_abmc_cfg() to resctrl_abmc_config_one_amd().

Added a new patch to fix counter assignment on event config changes.

Removed the references of ABMC from user interfaces.

Simplified the parsing (strsep(&token, "//") in rdtgroup_mbm_assign_control_write(). Added mutex lock in rdtgroup_mbm_assign_control_write() while processing.

Thomas Gleixner asked us to update https://gitlab.com/x86-cpuid.org/x86-cpuid-db.
It needs internal approval. We are working on it.

v6:
We still need to finalize few interface details on mbm_assign_mode and mbm_assign_control in case of ABMC and Soft-ABMC. We can continue the discussion with this series.

Added support for domain-id '*' to update all the domains at once. Fixed assign interface to allocate the counter if counter is not assigned.
Fixed unassign interface to free the counter if the counter is not assigned in any of the domains.

Renamed abmc_capable to mbm_cntr_assignable.

Renamed abmc_enabled to mbm_cntr_assign_enabled.
Used msr_set_bit and msr_clear_bit for msr updates.
Renamed resctrl_arch_abmc_enable() to resctrl_arch_mbm_cntr_assign_enable(). Renamed resctrl_arch_abmc_disable() to resctrl_arch_mbm_cntr_assign_disable().

Changed the display name from num_cntrs to num_mbm_cntrs.

Removed the variable mbm_cntrs_free_map_len. This is not required. Removed the call mbm_cntrs_init() in arch code. This needs to be done at higher level. Used DECLARE_BITMAP to initialize mbm_cntrs_free_map.
Removed unused config value definitions.

Introduced mbm_cntr_map to track counters at domain level. With this we dont need to send MSR read to read the counter configuration.

Separated all the counter id management to upper level in FS code.

Added checks to detect "Unassigned" before reading the RMID.

More details in each patch.

v5:
Rebase changes (because of SNC support)

Interface changes.
/sys/fs/resctrl/mbm_assign to /sys/fs/resctrl/mbm_assign_mode. /sys/fs/resctrl/mbm_assign_control to /sys/fs/resctrl/mbm_assign_control.

Added few arch specific routines.
resctrl_arch_get_abmc_enabled.
resctrl_arch_abmc_enable.
resctrl_arch_abmc_disable.

Few renames
num_cntrs_free_map -> mbm_cntrs_free_map num_cntrs_init -> mbm_cntrs_init arch_domain_mbm_evt_config -> resctrl_arch_mbm_evt_config

Introduced resctrl_arch_event_config_get and
resctrl_arch_event_config_set() to update event configuration.

Removed mon_state field mongroup. Added MON_CNTR_UNSET to initialize counters.

Renamed ctr_id to cntr_id for the hardware counter.

Report "Unassigned" in case the user attempts to read the events without assigning the counter.

ABMC is enabled during the boot up. Can be enabled or disabled later.

Fixed opcode and flags combination.

    '=_" is valid.
    "-_" amd "+_" is not valid.

Added all the comments as far as I know. If I missed something, it is not intentional.

v4:
Main change is domain specific event assignment.
Kept the ABMC feature as a default.
Dynamcic switching between ABMC and mbm_legacy is still allowed. We are still not clear about mount option.
Moved the monitoring related data in resctrl_mon structure from rdt_resource. Fixed the display of legacy and ABMC mode.
Used bimap APIs when possible.
Removed event configuration read from MSRs. We can use the internal saved data.(patch 12)
Added more comments about L3_QOS_ABMC_CFG MSR.
Added IPIs to read the assignment status for each domain (patch 18 and 19) More details in each patch.

v3:
This series adds the support for global assignment mode discussed in the thread. https://lore.kernel.org/lkml/[email protected]/
Removed the individual assignment mode and included the global assignment interface. Added following interface files.
a. /sys/fs/resctrl/info/L3_MON/mbm_assign
Used for displaying the current assignment mode and switch between ABMC and legacy mode.
b. /sys/fs/resctrl/info/L3_MON/mbm_assign_control
Used for lising the groups assignment mode and modify the assignment states.
c. Most of the changes are related to the new interface.
d. Addressed the comments from Reinette, James and Peter.
e. Hope I have addressed most of the major feedbacks discussed. If I missed
something then it is not intentional. Please feel free to comment.
f. Sending this as an RFC as per Reinette's comment. So, this is still open
for discussion.

v2:
a. Major change is the way ABMC is enabled. Earlier, user needed to remount
with -o abmc to enable ABMC feature. Removed that option now.
Now users can enable ABMC by "$echo 1 to /sys/fs/resctrl/info/L3_MON/mbm_assign_enable".

b. Added new word 21 to x86/cpufeatures.h.

c. Display unsupported if user attempts to read the events when ABMC is enabled
and event is not assigned.

d. Display monitor_state as "Unsupported" when ABMC is disabled.

e. Text updates and rebase to latest tip tree (as of Jan 18).

f. This series is still work in progress. I am yet to hear from ARM developers.

--------------------------------------------------------------------------------------

Previous revisions:
v15: https://lore.kernel.org/lkml/[email protected]/
v14: https://lore.kernel.org/lkml/[email protected]/
v13: https://lore.kernel.org/lkml/[email protected]/
v12: https://lore.kernel.org/lkml/[email protected]/
v11: https://lore.kernel.org/lkml/[email protected]/
v10: https://lore.kernel.org/lkml/[email protected]/
v9: https://lore.kernel.org/lkml/[email protected]/
v8: https://lore.kernel.org/lkml/[email protected]/
v7: https://lore.kernel.org/lkml/[email protected]/
v6: https://lore.kernel.org/lkml/[email protected]/
v5: https://lore.kernel.org/lkml/[email protected]/
v4: https://lore.kernel.org/lkml/[email protected]/
v3: https://lore.kernel.org/lkml/[email protected]/
v2: https://lore.kernel.org/lkml/[email protected]/
v1: https://lore.kernel.org/lkml/[email protected]/
----------------------------------------------------------------------------

Babu Moger (30):
x86/cpufeatures: Add support for Assignable Bandwidth Monitoring
Counters (ABMC)
x86/resctrl: Add ABMC feature in the command line options x86,fs/resctrl: Consolidate monitoring related data from rdt_resource x86,fs/resctrl: Detect Assignable Bandwidth Monitoring feature details x86/resctrl: Add support to enable/disable AMD ABMC feature fs/resctrl: Introduce the interface to display monitoring modes fs/resctrl: Add resctrl file to display number of assignable counters fs/resctrl: Introduce mbm_cntr_cfg to track assignable counters per
domain
fs/resctrl: Introduce interface to display number of free MBM counters x86/resctrl: Add data structures and definitions for ABMC assignment fs/resctrl: Introduce event configuration field in struct mon_evt x86,fs/resctrl: Implement resctrl_arch_config_cntr() to assign a
counter with ABMC
fs/resctrl: Add the functionality to assign MBM events fs/resctrl: Add the functionality to unassign MBM events fs/resctrl: Pass struct rdtgroup instead of individual members fs/resctrl: Introduce counter ID read, reset calls in mbm_event mode x86/resctrl: Refactor resctrl_arch_rmid_read() x86/resctrl: Implement resctrl_arch_reset_cntr() and
resctrl_arch_cntr_read()
fs/resctrl: Support counter read/reset with mbm_event assignment mode fs/resctrl: Add definitions for MBM event configuration fs/resctrl: Add event configuration directory under info/L3_MON/ fs/resctrl: Provide interface to update the event configurations fs/resctrl: Introduce mbm_assign_on_mkdir to enable assignments on
mkdir
fs/resctrl: Auto assign counters on mkdir and clean up on group
removal
fs/resctrl: Introduce mbm_L3_assignments to list assignments in a
group
fs/resctrl: Introduce the interface to modify assignments in a group fs/resctrl: Disable BMEC event configuration when mbm_event mode is
enabled
fs/resctrl: Introduce the interface to switch between monitor modes x86/resctrl: Configure mbm_event mode if supported
MAINTAINERS: resctrl: add myself as reviewer

Tony Luck (4):
x86,fs/resctrl: Consolidate monitor event descriptions x86,fs/resctrl: Replace architecture event enabled checks x86/resctrl: Remove 'rdt_mon_features' global variable x86,fs/resctrl: Prepare for more monitor events

 .../admin-guide/kernel-parameters.txt         |   2 +-
 Documentation/filesystems/resctrl.rst         | 312 +++++++++
 MAINTAINERS                                   |   1 +
 arch/x86/include/asm/cpufeatures.h            |   1 +
 arch/x86/include/asm/msr-index.h              |   2 +
 arch/x86/include/asm/resctrl.h                |  16 -
 arch/x86/kernel/cpu/resctrl/core.c            |  79 ++-
 arch/x86/kernel/cpu/resctrl/internal.h        |  56 +-
 arch/x86/kernel/cpu/resctrl/monitor.c         | 247 +++++--
 arch/x86/kernel/cpu/scattered.c               |   1 +
 fs/resctrl/ctrlmondata.c                      |  26 +-
 fs/resctrl/internal.h                         |  54 +-
 fs/resctrl/monitor.c                          | 637 ++++++++++++++++--
 fs/resctrl/rdtgroup.c                         | 588 ++++++++++++++--
 include/linux/resctrl.h                       | 148 +++-
 include/linux/resctrl_types.h                 |  18 +-
 16 files changed, 1962 insertions(+), 226 deletions(-)

2.34.1

From: Tony Luck <[email protected]>

There are currently only three monitor events, all associated with the RDT_RESOURCE_L3 resource. Growing support for additional events will be easier with some restructuring to have a single point in file system code where all attributes of all events are defined.

Place all event descriptions into an array mon_event_all[]. Doing this has the beneficial side effect of removing the need for rdt_resource::evt_list.

Add resctrl_event_id::QOS_FIRST_EVENT for a lower bound on range checks for event ids and as the starting index to scan mon_event_all[].

Drop the code that builds evt_list and change the two places where the list is scanned to scan mon_event_all[] instead using a new helper macro for_each_mon_event().

Architecture code now informs file system code which events are available with resctrl_enable_mon_event().

---
Picked up first four patches from:
https://lore.kernel.org/lkml/[email protected]/
These patches have already been reviewed.

---
 arch/x86/kernel/cpu/resctrl/core.c | 12 ++++--
 fs/resctrl/internal.h              | 13 ++++--
 fs/resctrl/monitor.c               | 63 +++++++++++++++---------------
 fs/resctrl/rdtgroup.c              | 11 +++---
 include/linux/resctrl.h            |  4 +-
 include/linux/resctrl_types.h      | 12 ++++--
 6 files changed, 66 insertions(+), 49 deletions(-)

index 187d527ef73b..7fcae25874fe 100644
@@ -864,12 +864,18 @@ static __init bool get_rdt_mon_resources(void)
 {
 	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
 
-	if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC))
+	if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) {
+		resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID);
 		rdt_mon_features |= (1 << QOS_L3_OCCUP_EVENT_ID);
-	if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL))
+	}
+	if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) {
+		resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID);
 		rdt_mon_features |= (1 << QOS_L3_MBM_TOTAL_EVENT_ID);
-	if (rdt_cpu_has(X86_FEATURE_CQM_MBM_LOCAL))
+	}
+	if (rdt_cpu_has(X86_FEATURE_CQM_MBM_LOCAL)) {
+		resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
 		rdt_mon_features |= (1 << QOS_L3_MBM_LOCAL_EVENT_ID);
+	}
 
 	if (!rdt_mon_features)
 		return false;

index 0a1eedba2b03..4f315b7e9ec0 100644
@@ -52,19 +52,26 @@ static inline struct rdt_fs_context *rdt_fc2context(struct fs_context *fc)
 }
 
 /**
- * struct mon_evt - Entry in the event list of a resource
+ * struct mon_evt - Properties of a monitor event
  * @evtid:		event id
+ * @rid:		resource id for this event
  * @name:		name of the event
  * @configurable:	true if the event is configurable
- * @list:		entry in &rdt_resource->evt_list
+ * @enabled:		true if the event is enabled
  */
 struct mon_evt {
 	enum resctrl_event_id	evtid;
+	enum resctrl_res_level	rid;
 	char			*name;
 	bool			configurable;
-	struct list_head	list;
+	bool			enabled;
 };
 
+extern struct mon_evt mon_event_all[QOS_NUM_EVENTS];
+
+#define for_each_mon_event(mevt) for (mevt = &mon_event_all[QOS_FIRST_EVENT];	\
+				      mevt < &mon_event_all[QOS_NUM_EVENTS]; mevt++)
+
 /**
  * struct mon_data - Monitoring details for each event file.
  * @list:            Member of the global @mon_data_kn_priv_list list.

index 77d08229d855..b95501d4b5de 100644
@@ -1152,7 +1152,9 @@ static int rdt_mon_features_show(struct kernfs_open_file *of,
 	struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
 	struct mon_evt *mevt;
 
-	list_for_each_entry(mevt, &r->evt_list, list) {
+	for_each_mon_event(mevt) {
+		if (mevt->rid != r->rid || !mevt->enabled)
+			continue;
 		seq_printf(seq, "%s\n", mevt->name);
 		if (mevt->configurable)
 			seq_printf(seq, "%s_config\n", mevt->name);

@@ -3057,10 +3059,9 @@ static int mon_add_all_files(struct kernfs_node *kn, struct rdt_mon_domain *d,
 	struct mon_evt *mevt;
 	int ret, domid;
 
-	if (WARN_ON(list_empty(&r->evt_list)))
-		return -EPERM;
-
-	list_for_each_entry(mevt, &r->evt_list, list) {
+	for_each_mon_event(mevt) {
+		if (mevt->rid != r->rid || !mevt->enabled)
+			continue;
 		domid = do_sum ? d->ci_id : d->hdr.id;
 		priv = mon_get_kn_priv(r->rid, domid, mevt, do_sum);
 		if (WARN_ON_ONCE(!priv))

index 6fb4894b8cfd..2944042bd84c 100644
@@ -269,7 +269,6 @@ enum resctrl_schema_fmt {
  * @mon_domains:	RCU list of all monitor domains for this resource
  * @name:		Name to use in "schemata" file.
  * @schema_fmt:		Which format string and parser is used for this schema.
- * @evt_list:		List of monitoring events
  * @mbm_cfg_mask:	Bandwidth sources that can be tracked when bandwidth
  *			monitoring events can be configured.
  * @cdp_capable:	Is the CDP feature available on this resource

@@ -287,7 +286,6 @@ struct rdt_resource {
 	struct list_head	mon_domains;
 	char			*name;
 	enum resctrl_schema_fmt	schema_fmt;
-	struct list_head	evt_list;
 	unsigned int		mbm_cfg_mask;
 	bool			cdp_capable;
 };

@@ -372,6 +370,8 @@ u32 resctrl_arch_get_num_closid(struct rdt_resource *r);
 u32 resctrl_arch_system_num_rmid_idx(void);
 int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
 
+void resctrl_enable_mon_event(enum resctrl_event_id eventid);
+
 bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt);
 
 /**

index a25fb9c4070d..2dadbc54e4b3 100644
@@ -34,11 +34,15 @@
 /* Max event bits supported */
 #define MAX_EVT_CONFIG_BITS		GENMASK(6, 0)
 
-/*
- * Event IDs, the values match those used to program IA32_QM_EVTSEL before
- * reading IA32_QM_CTR on RDT systems.
- */
+/* Event IDs */
 enum resctrl_event_id {
+	/* Must match value of first event below */
+	QOS_FIRST_EVENT			= 0x01,
+
+	/*
+	 * These values match those used to program IA32_QM_EVTSEL before
+	 * reading IA32_QM_CTR on RDT systems.
+	 */
 	QOS_L3_OCCUP_EVENT_ID		= 0x01,
 	QOS_L3_MBM_TOTAL_EVENT_ID	= 0x02,
 	QOS_L3_MBM_LOCAL_EVENT_ID	= 0x03,

2.34.1

Hi Babu,

Please add your "Signed-off-by" to the commit tags of the first four patches. When you do, ensure it follows the expected ordering
per "Ordering of commit tags" in Documentation/process/maintainer-tip.rst.

Reinette

Hi Reinette,

Sure. It appears I am patch handler in this case. Seems like this is a correct order.

Thanks
Babu Moger

From: Tony Luck <[email protected]>

The resctrl file system now has complete knowledge of the status of every event. So there is no need for per-event function calls to check.

Replace each of the resctrl_arch_is_{event}enabled() calls with resctrl_is_mon_event_enabled(QOS_{EVENT}).

No functional change.

---
Picked up first four patches from:
https://lore.kernel.org/lkml/[email protected]/
These patches have already been reviewed.

---
 arch/x86/include/asm/resctrl.h        | 15 ---------------
 arch/x86/kernel/cpu/resctrl/core.c    |  4 ++--
 arch/x86/kernel/cpu/resctrl/monitor.c |  4 ++--
 fs/resctrl/ctrlmondata.c              |  4 ++--
 fs/resctrl/monitor.c                  | 16 +++++++++++-----
 fs/resctrl/rdtgroup.c                 | 18 +++++++++---------
 include/linux/resctrl.h               |  2 ++
 7 files changed, 28 insertions(+), 35 deletions(-)

index feb93b50e990..b1dd5d6b87db 100644
@@ -84,21 +84,6 @@ static inline void resctrl_arch_disable_mon(void)
 	static_branch_dec_cpuslocked(&rdt_enable_key);
 }
 
-static inline bool resctrl_arch_is_llc_occupancy_enabled(void)
-{
-	return (rdt_mon_features & (1 << QOS_L3_OCCUP_EVENT_ID));
-}
-
-static inline bool resctrl_arch_is_mbm_total_enabled(void)
-{
-	return (rdt_mon_features & (1 << QOS_L3_MBM_TOTAL_EVENT_ID));
-}
-
-static inline bool resctrl_arch_is_mbm_local_enabled(void)
-{
-	return (rdt_mon_features & (1 << QOS_L3_MBM_LOCAL_EVENT_ID));
-}
-
 /*
  * __resctrl_sched_in() - Writes the task's CLOSid/RMID to IA32_PQR_MSR
  *

index 7fcae25874fe..1a319ce9328c 100644
@@ -402,13 +402,13 @@ static int arch_domain_mbm_alloc(u32 num_rmid, struct rdt_hw_mon_domain *hw_dom)
 {
 	size_t tsize;
 
-	if (resctrl_arch_is_mbm_total_enabled()) {
+	if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID)) {
 		tsize = sizeof(*hw_dom->arch_mbm_total);
 		hw_dom->arch_mbm_total = kcalloc(num_rmid, tsize, GFP_KERNEL);
 		if (!hw_dom->arch_mbm_total)
 			return -ENOMEM;
 	}
-	if (resctrl_arch_is_mbm_local_enabled()) {
+	if (resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID)) {
 		tsize = sizeof(*hw_dom->arch_mbm_local);
 		hw_dom->arch_mbm_local = kcalloc(num_rmid, tsize, GFP_KERNEL);
 		if (!hw_dom->arch_mbm_local) {

index c261558276cd..61d38517e2bf 100644
@@ -207,11 +207,11 @@ void resctrl_arch_reset_rmid_all(struct rdt_resource *r, struct rdt_mon_domain *
 {
 	struct rdt_hw_mon_domain *hw_dom = resctrl_to_arch_mon_dom(d);
 
-	if (resctrl_arch_is_mbm_total_enabled())
+	if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID))
 		memset(hw_dom->arch_mbm_total, 0,
 		       sizeof(*hw_dom->arch_mbm_total) * r->num_rmid);
 
-	if (resctrl_arch_is_mbm_local_enabled())
+	if (resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID))
 		memset(hw_dom->arch_mbm_local, 0,
 		       sizeof(*hw_dom->arch_mbm_local) * r->num_rmid);
 }

index d98e0d2de09f..ad7ffc6acf13 100644
@@ -473,12 +473,12 @@ ssize_t rdtgroup_mba_mbps_event_write(struct kernfs_open_file *of,
 	rdt_last_cmd_clear();
 
 	if (!strcmp(buf, "mbm_local_bytes")) {
-		if (resctrl_arch_is_mbm_local_enabled())
+		if (resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID))
 			rdtgrp->mba_mbps_event = QOS_L3_MBM_LOCAL_EVENT_ID;
 		else
 			ret = -EINVAL;
 	} else if (!strcmp(buf, "mbm_total_bytes")) {
-		if (resctrl_arch_is_mbm_total_enabled())
+		if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID))
 			rdtgrp->mba_mbps_event = QOS_L3_MBM_TOTAL_EVENT_ID;
 		else
 			ret = -EINVAL;

index 2313e48de55f..9e988b2c1a22 100644
@@ -336,7 +336,7 @@ void free_rmid(u32 closid, u32 rmid)
 
 	entry = __rmid_entry(idx);
 
-	if (resctrl_arch_is_llc_occupancy_enabled())
+	if (resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID))
 		add_rmid_to_limbo(entry);
 	else
 		list_add_tail(&entry->list, &rmid_free_lru);

@@ -637,10 +637,10 @@ static void mbm_update(struct rdt_resource *r, struct rdt_mon_domain *d,
 	 * This is protected from concurrent reads from user as both
 	 * the user and overflow handler hold the global mutex.
 	 */
-	if (resctrl_arch_is_mbm_total_enabled())
+	if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID))
 		mbm_update_one_event(r, d, closid, rmid, QOS_L3_MBM_TOTAL_EVENT_ID);
 
-	if (resctrl_arch_is_mbm_local_enabled())
+	if (resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID))
 		mbm_update_one_event(r, d, closid, rmid, QOS_L3_MBM_LOCAL_EVENT_ID);
 }
 

@@ -879,6 +879,12 @@ void resctrl_enable_mon_event(enum resctrl_event_id eventid)
 	mon_event_all[eventid].enabled = true;
 }
 
+bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid)
+{
+	return eventid >= QOS_FIRST_EVENT && eventid < QOS_NUM_EVENTS &&
+	       mon_event_all[eventid].enabled;
+}
+
 /**
  * resctrl_mon_resource_init() - Initialise global monitoring structures.
  *

@@ -914,9 +920,9 @@ int resctrl_mon_resource_init(void)
 					 RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
 	}
 
-	if (resctrl_arch_is_mbm_local_enabled())
+	if (resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID))
 		mba_mbps_default_event = QOS_L3_MBM_LOCAL_EVENT_ID;
-	else if (resctrl_arch_is_mbm_total_enabled())
+	else if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID))
 		mba_mbps_default_event = QOS_L3_MBM_TOTAL_EVENT_ID;
 
 	return 0;

index b95501d4b5de..a7eeb33501da 100644
@@ -123,8 +123,8 @@ void rdt_staged_configs_clear(void)
 
 static bool resctrl_is_mbm_enabled(void)
 {
-	return (resctrl_arch_is_mbm_total_enabled() ||
-		resctrl_arch_is_mbm_local_enabled());
+	return (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID) ||
+		resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID));
 }
 
 static bool resctrl_is_mbm_event(int e)

@@ -196,7 +196,7 @@ static int closid_alloc(void)
 	lockdep_assert_held(&rdtgroup_mutex);
 
 	if (IS_ENABLED(CONFIG_RESCTRL_RMID_DEPENDS_ON_CLOSID) &&
-	    resctrl_arch_is_llc_occupancy_enabled()) {
+	    resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID)) {
 		cleanest_closid = resctrl_find_cleanest_closid();
 		if (cleanest_closid < 0)
 			return cleanest_closid;

@@ -4051,7 +4051,7 @@ void resctrl_offline_mon_domain(struct rdt_resource *r, struct rdt_mon_domain *d
 
 	if (resctrl_is_mbm_enabled())
 		cancel_delayed_work(&d->mbm_over);
-	if (resctrl_arch_is_llc_occupancy_enabled() && has_busy_rmid(d)) {
+	if (resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID) && has_busy_rmid(d)) {
 		/*
 		 * When a package is going down, forcefully
 		 * decrement rmid->ebusy. There is no way to know

@@ -4087,12 +4087,12 @@ static int domain_setup_mon_state(struct rdt_resource *r, struct rdt_mon_domain
 	u32 idx_limit = resctrl_arch_system_num_rmid_idx();
 	size_t tsize;
 
-	if (resctrl_arch_is_llc_occupancy_enabled()) {
+	if (resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID)) {
 		d->rmid_busy_llc = bitmap_zalloc(idx_limit, GFP_KERNEL);
 		if (!d->rmid_busy_llc)
 			return -ENOMEM;
 	}
-	if (resctrl_arch_is_mbm_total_enabled()) {
+	if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID)) {
 		tsize = sizeof(*d->mbm_total);
 		d->mbm_total = kcalloc(idx_limit, tsize, GFP_KERNEL);
 		if (!d->mbm_total) {

@@ -4100,7 +4100,7 @@ static int domain_setup_mon_state(struct rdt_resource *r, struct rdt_mon_domain
 			return -ENOMEM;
 		}
 	}
-	if (resctrl_arch_is_mbm_local_enabled()) {
+	if (resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID)) {
 		tsize = sizeof(*d->mbm_local);
 		d->mbm_local = kcalloc(idx_limit, tsize, GFP_KERNEL);
 		if (!d->mbm_local) {

@@ -4145,7 +4145,7 @@ int resctrl_online_mon_domain(struct rdt_resource *r, struct rdt_mon_domain *d)
 					   RESCTRL_PICK_ANY_CPU);
 	}
 
-	if (resctrl_arch_is_llc_occupancy_enabled())
+	if (resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID))
 		INIT_DELAYED_WORK(&d->cqm_limbo, cqm_handle_limbo);
 
 	/*

@@ -4220,7 +4220,7 @@ void resctrl_offline_cpu(unsigned int cpu)
 			cancel_delayed_work(&d->mbm_over);
 			mbm_setup_overflow_handler(d, 0, cpu);
 		}
-		if (resctrl_arch_is_llc_occupancy_enabled() &&
+		if (resctrl_is_mon_event_enabled(QOS_L3_OCCUP_EVENT_ID) &&
 		    cpu == d->cqm_work_cpu && has_busy_rmid(d)) {
 			cancel_delayed_work(&d->cqm_limbo);
 			cqm_setup_limbo_handler(d, 0, cpu);

index 2944042bd84c..40aba6b5d4f0 100644
@@ -372,6 +372,8 @@ int resctrl_arch_update_domains(struct rdt_resource *r, u32 closid);
 
 void resctrl_enable_mon_event(enum resctrl_event_id eventid);
 
+bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid);
+
 bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt);
 
 /**

2.34.1

From: Tony Luck <[email protected]>

rdt_mon_features is used as a bitmask of enabled monitor events. A monitor event's status is now maintained in mon_evt::enabled with all monitor events' mon_evt structures found in the filesystem's mon_event_all[] array.

Remove the remaining uses of rdt_mon_features.

---
Picked up first four patches from:
https://lore.kernel.org/lkml/[email protected]/
These patches have already been reviewed.

---
 arch/x86/include/asm/resctrl.h        | 1 -
 arch/x86/kernel/cpu/resctrl/core.c    | 9 +++++----
 arch/x86/kernel/cpu/resctrl/monitor.c | 5 -----
 3 files changed, 5 insertions(+), 10 deletions(-)

index b1dd5d6b87db..575f8408a9e7 100644
@@ -44,7 +44,6 @@ DECLARE_PER_CPU(struct resctrl_pqr_state, pqr_state);
 
 extern bool rdt_alloc_capable;
 extern bool rdt_mon_capable;
-extern unsigned int rdt_mon_features;
 
 DECLARE_STATIC_KEY_FALSE(rdt_enable_key);
 DECLARE_STATIC_KEY_FALSE(rdt_alloc_enable_key);

index 1a319ce9328c..5d14f9a14eda 100644
@@ -863,21 +863,22 @@ static __init bool get_rdt_alloc_resources(void)
 static __init bool get_rdt_mon_resources(void)
 {
 	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
+	bool ret = false;
 
 	if (rdt_cpu_has(X86_FEATURE_CQM_OCCUP_LLC)) {
 		resctrl_enable_mon_event(QOS_L3_OCCUP_EVENT_ID);
-		rdt_mon_features |= (1 << QOS_L3_OCCUP_EVENT_ID);
+		ret = true;
 	}
 	if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL)) {
 		resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID);
-		rdt_mon_features |= (1 << QOS_L3_MBM_TOTAL_EVENT_ID);
+		ret = true;
 	}
 	if (rdt_cpu_has(X86_FEATURE_CQM_MBM_LOCAL)) {
 		resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
-		rdt_mon_features |= (1 << QOS_L3_MBM_LOCAL_EVENT_ID);
+		ret = true;
 	}
 
-	if (!rdt_mon_features)
+	if (!ret)
 		return false;
 
 	return !rdt_get_mon_l3_config(r);

index 61d38517e2bf..07f8ab097cbe 100644
@@ -31,11 +31,6 @@
  */
 bool rdt_mon_capable;
 
-/*
- * Global to indicate which monitoring events are enabled.
- */
-unsigned int rdt_mon_features;
-
 #define CF(cf)	((unsigned long)(1048576 * (cf) + 0.5))
 
 static int snc_nodes_per_l3_cache = 1;

2.34.1

From: Tony Luck <[email protected]>

There's a rule in computer programming that objects appear zero, once, or many times. So code accordingly.

There are two MBM events and resctrl is coded with a lot of

if (local)
do one thing
if (total)
do a different thing

Change the rdt_mon_domain and rdt_hw_mon_domain structures to hold arrays of pointers to per event data instead of explicit fields for total and local bandwidth.

Simplify by coding for many events using loops on which are enabled.

Move resctrl_is_mbm_event() to <linux/resctrl.h> so it can be used more widely. Also provide a for_each_mbm_event_id() helper macro.

Cleanup variable names in functions touched to consistently use "eventid" for those with type enum resctrl_event_id.

---
Picked up first four patches from:
https://lore.kernel.org/lkml/[email protected]/
These patches have already been reviewed.

---
 arch/x86/kernel/cpu/resctrl/core.c     | 40 +++++++++++----------
 arch/x86/kernel/cpu/resctrl/internal.h |  8 ++---
 arch/x86/kernel/cpu/resctrl/monitor.c  | 36 +++++++++----------
 fs/resctrl/monitor.c                   | 13 ++++---
 fs/resctrl/rdtgroup.c                  | 50 +++++++++++++-------------
 include/linux/resctrl.h                | 23 +++++++++---
 include/linux/resctrl_types.h          |  3 ++
 7 files changed, 96 insertions(+), 77 deletions(-)

index 5d14f9a14eda..fbf019c1ff11 100644
@@ -365,8 +365,10 @@ static void ctrl_domain_free(struct rdt_hw_ctrl_domain *hw_dom)
 
 static void mon_domain_free(struct rdt_hw_mon_domain *hw_dom)
 {
-	kfree(hw_dom->arch_mbm_total);
-	kfree(hw_dom->arch_mbm_local);
+	int idx;
+
+	for_each_mbm_idx(idx)
+		kfree(hw_dom->arch_mbm_states[idx]);
 	kfree(hw_dom);
 }
 

@@ -400,25 +402,27 @@ static int domain_setup_ctrlval(struct rdt_resource *r, struct rdt_ctrl_domain *
  */
 static int arch_domain_mbm_alloc(u32 num_rmid, struct rdt_hw_mon_domain *hw_dom)
 {
-	size_t tsize;
-
-	if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID)) {
-		tsize = sizeof(*hw_dom->arch_mbm_total);
-		hw_dom->arch_mbm_total = kcalloc(num_rmid, tsize, GFP_KERNEL);
-		if (!hw_dom->arch_mbm_total)
-			return -ENOMEM;
-	}
-	if (resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID)) {
-		tsize = sizeof(*hw_dom->arch_mbm_local);
-		hw_dom->arch_mbm_local = kcalloc(num_rmid, tsize, GFP_KERNEL);
-		if (!hw_dom->arch_mbm_local) {
-			kfree(hw_dom->arch_mbm_total);
-			hw_dom->arch_mbm_total = NULL;
-			return -ENOMEM;
-		}
+	size_t tsize = sizeof(*hw_dom->arch_mbm_states[0]);
+	enum resctrl_event_id eventid;
+	int idx;
+
+	for_each_mbm_event_id(eventid) {
+		if (!resctrl_is_mon_event_enabled(eventid))
+			continue;
+		idx = MBM_STATE_IDX(eventid);
+		hw_dom->arch_mbm_states[idx] = kcalloc(num_rmid, tsize, GFP_KERNEL);
+		if (!hw_dom->arch_mbm_states[idx])
+			goto cleanup;
 	}
 
 	return 0;
+cleanup:
+	for_each_mbm_idx(idx) {
+		kfree(hw_dom->arch_mbm_states[idx]);
+		hw_dom->arch_mbm_states[idx] = NULL;
+	}
+
+	return -ENOMEM;
 }
 
 static int get_domain_id_from_scope(int cpu, enum resctrl_scope scope)

index 5e3c41b36437..58dca892a5df 100644
@@ -54,15 +54,15 @@ struct rdt_hw_ctrl_domain {
  * struct rdt_hw_mon_domain - Arch private attributes of a set of CPUs that share
  *			      a resource for a monitor function
  * @d_resctrl:	Properties exposed to the resctrl file system
- * @arch_mbm_total:	arch private state for MBM total bandwidth
- * @arch_mbm_local:	arch private state for MBM local bandwidth
+ * @arch_mbm_states:	Per-event pointer to the MBM event's saved state.
+ *			An MBM event's state is an array of struct arch_mbm_state
+ *			indexed by RMID on x86.
  *
  * Members of this structure are accessed via helpers that provide abstraction.
  */
 struct rdt_hw_mon_domain {
 	struct rdt_mon_domain		d_resctrl;
-	struct arch_mbm_state		*arch_mbm_total;
-	struct arch_mbm_state		*arch_mbm_local;
+	struct arch_mbm_state		*arch_mbm_states[QOS_NUM_L3_MBM_EVENTS];
 };
 
 static inline struct rdt_hw_ctrl_domain *resctrl_to_arch_ctrl_dom(struct rdt_ctrl_domain *r)

index 07f8ab097cbe..f01db2034d08 100644
@@ -161,18 +161,14 @@ static struct arch_mbm_state *get_arch_mbm_state(struct rdt_hw_mon_domain *hw_do
 						 u32 rmid,
 						 enum resctrl_event_id eventid)
 {
-	switch (eventid) {
-	case QOS_L3_OCCUP_EVENT_ID:
-		return NULL;
-	case QOS_L3_MBM_TOTAL_EVENT_ID:
-		return &hw_dom->arch_mbm_total[rmid];
-	case QOS_L3_MBM_LOCAL_EVENT_ID:
-		return &hw_dom->arch_mbm_local[rmid];
-	default:
-		/* Never expect to get here */
-		WARN_ON_ONCE(1);
+	struct arch_mbm_state *state;
+
+	if (!resctrl_is_mbm_event(eventid))
 		return NULL;
-	}
+
+	state = hw_dom->arch_mbm_states[MBM_STATE_IDX(eventid)];
+
+	return state ? &state[rmid] : NULL;
 }
 
 void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_mon_domain *d,

@@ -201,14 +197,16 @@ void resctrl_arch_reset_rmid(struct rdt_resource *r, struct rdt_mon_domain *d,
 void resctrl_arch_reset_rmid_all(struct rdt_resource *r, struct rdt_mon_domain *d)
 {
 	struct rdt_hw_mon_domain *hw_dom = resctrl_to_arch_mon_dom(d);
-
-	if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID))
-		memset(hw_dom->arch_mbm_total, 0,
-		       sizeof(*hw_dom->arch_mbm_total) * r->num_rmid);
-
-	if (resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID))
-		memset(hw_dom->arch_mbm_local, 0,
-		       sizeof(*hw_dom->arch_mbm_local) * r->num_rmid);
+	enum resctrl_event_id eventid;
+	int idx;
+
+	for_each_mbm_event_id(eventid) {
+		if (!resctrl_is_mon_event_enabled(eventid))
+			continue;
+		idx = MBM_STATE_IDX(eventid);
+		memset(hw_dom->arch_mbm_states[idx], 0,
+		       sizeof(*hw_dom->arch_mbm_states[0]) * r->num_rmid);
+	}
 }
 
 static u64 mbm_overflow_count(u64 prev_msr, u64 cur_msr, unsigned int width)

index 9e988b2c1a22..dcc6c00eb362 100644
@@ -346,15 +346,14 @@ static struct mbm_state *get_mbm_state(struct rdt_mon_domain *d, u32 closid,
 				       u32 rmid, enum resctrl_event_id evtid)
 {
 	u32 idx = resctrl_arch_rmid_idx_encode(closid, rmid);
+	struct mbm_state *state;
 
-	switch (evtid) {
-	case QOS_L3_MBM_TOTAL_EVENT_ID:
-		return &d->mbm_total[idx];
-	case QOS_L3_MBM_LOCAL_EVENT_ID:
-		return &d->mbm_local[idx];
-	default:
+	if (!resctrl_is_mbm_event(evtid))
 		return NULL;
-	}
+
+	state = d->mbm_states[MBM_STATE_IDX(evtid)];
+
+	return state ? &state[idx] : NULL;
 }
 
 static int __mon_event_count(u32 closid, u32 rmid, struct rmid_read *rr)

index 40aba6b5d4f0..478d7a935ca3 100644
@@ -161,8 +161,9 @@ struct rdt_ctrl_domain {
  * @hdr:		common header for different domain types
  * @ci_id:		cache info id for this domain
  * @rmid_busy_llc:	bitmap of which limbo RMIDs are above threshold
- * @mbm_total:		saved state for MBM total bandwidth
- * @mbm_local:		saved state for MBM local bandwidth
+ * @mbm_states:		Per-event pointer to the MBM event's saved state.
+ *			An MBM event's state is an array of struct mbm_state
+ *			indexed by RMID on x86 or combined CLOSID, RMID on Arm.
  * @mbm_over:		worker to periodically read MBM h/w counters
  * @cqm_limbo:		worker to periodically read CQM h/w counters
  * @mbm_work_cpu:	worker CPU for MBM h/w counters

@@ -172,8 +173,7 @@ struct rdt_mon_domain {
 	struct rdt_domain_hdr		hdr;
 	unsigned int			ci_id;
 	unsigned long			*rmid_busy_llc;
-	struct mbm_state		*mbm_total;
-	struct mbm_state		*mbm_local;
+	struct mbm_state		*mbm_states[QOS_NUM_L3_MBM_EVENTS];
 	struct delayed_work		mbm_over;
 	struct delayed_work		cqm_limbo;
 	int				mbm_work_cpu;

@@ -376,6 +376,21 @@ bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid);
 
 bool resctrl_arch_is_evt_configurable(enum resctrl_event_id evt);
 
+static inline bool resctrl_is_mbm_event(enum resctrl_event_id eventid)
+{
+	return (eventid >= QOS_L3_MBM_TOTAL_EVENT_ID &&
+		eventid <= QOS_L3_MBM_LOCAL_EVENT_ID);
+}
+
+/* Iterate over all memory bandwidth events */
+#define for_each_mbm_event_id(eventid)				\
+	for (eventid = QOS_L3_MBM_TOTAL_EVENT_ID;		\
+	     eventid <= QOS_L3_MBM_LOCAL_EVENT_ID; eventid++)
+
+/* Iterate over memory bandwidth arrays in domain structures */
+#define for_each_mbm_idx(idx)					\
+	for (idx = 0; idx < QOS_NUM_L3_MBM_EVENTS; idx++)
+
 /**
  * resctrl_arch_mon_event_config_write() - Write the config for an event.
  * @config_info: struct resctrl_mon_config_info describing the resource, domain

index 2dadbc54e4b3..d98351663c2c 100644
@@ -51,4 +51,7 @@ enum resctrl_event_id {
 	QOS_NUM_EVENTS,
 };
 
+#define QOS_NUM_L3_MBM_EVENTS	(QOS_L3_MBM_LOCAL_EVENT_ID - QOS_L3_MBM_TOTAL_EVENT_ID + 1)
+#define MBM_STATE_IDX(evt)	((evt) - QOS_L3_MBM_TOTAL_EVENT_ID)
+
 #endif /* __LINUX_RESCTRL_TYPES_H */

2.34.1

Users can create as many monitor groups as RMIDs supported by the hardware. However, bandwidth monitoring feature on AMD system only guarantees that RMIDs currently assigned to a processor will be tracked by hardware. The counters of any other RMIDs which are no longer being tracked will be reset to zero. The MBM event counters return "Unavailable" for the RMIDs that are not tracked by hardware. So, there can be only limited number of groups that can give guaranteed monitoring numbers. With ever changing configurations there is no way to definitely know which of these groups are being tracked during a particular time. Users do not have the option to monitor a group or set of groups for a certain period of time without worrying about RMID being reset in between.

The ABMC feature allows users to assign a hardware counter to an RMID, event pair and monitor bandwidth usage as long as it is assigned. The hardware continues to track the assigned counter until it is explicitly unassigned by the user. There is no need to worry about counters being reset during this period. Additionally, the user can specify the type of memory transactions (e.g., reads, writes) for the counter to track.

Without ABMC enabled, monitoring will work in current mode without assignment option.

The Linux resctrl subsystem provides an interface that allows monitoring of up to two memory bandwidth events per group, selected from a combination of available total and local events. When ABMC is enabled, two events will be assigned to each group by default, in line with the current interface design. Users will also have the option to configure which types of memory transactions are counted by these events.

Due to the limited number of available counters (32), users may quickly exhaust the available counters. If the system runs out of assignable ABMC counters, the kernel will report an error. In such cases, users will need to unassign one or more active counters to free up counters for new assignments. resctrl will provide options to assign or unassign events through the group-specific interface file.

The feature is detected via CPUID_Fn80000020_EBX_x00 bit 5. Bits Description
5 ABMC (Assignable Bandwidth Monitoring Counters)

The feature details are documented in APM listed below [1].
[1] AMD64 Architecture Programmer's Manual Volume 2: System Programming Publication # 24593 Revision 3.41 section 19.3.3.3 Assignable Bandwidth Monitoring (ABMC).

---
Note: Checkpatch checks/warnings are ignored to maintain coding style.

v16: Fixed the conflicts with latest cpufeatures.h and scattered.c files.

v15: Minor changelog update.

v14: Removed the dependancy on X86_FEATURE_CQM_MBM_TOTAL and X86_FEATURE_CQM_MBM_LOCAL.
as discussed in https://lore.kernel.org/lkml/[email protected]/
Need to re-work on ABMC enumeration during the init.
Updated changelog with few text update.

v13: Updated the commit log with Linux interface details.

v12: Removed the dependancy on X86_FEATURE_BMEC.
Removed the Reviewed-by tag as patch has changed.

v11: No changes.

v10: No changes.

v9: Took care of couple of minor merge conflicts. No other changes.

v8: No changes.

v7: Removed "" from feature flags. Not required anymore.

    https://lore.kernel.org/lkml/20240817145058.GCZsC40neU4wkPXeVR@fat_crate.local/

v6: Added Reinette's Reviewed-by. Moved the Checkpatch note below ---.

v5: Minor rebase change and subject line update.

v4: Changes because of rebase. Feature word 21 has few more additions now.
Changed the text to "tracked by hardware" instead of active.

v3: Change because of rebase. Actual patch did not change.

v2: Added dependency on X86_FEATURE_BMEC.

---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kernel/cpu/scattered.c    | 1 +
 2 files changed, 2 insertions(+)

index 602957dd2609..43cba78a50e5 100644
@@ -494,6 +494,7 @@
 #define X86_FEATURE_TSA_SQ_NO		(21*32+11) /* AMD CPU not vulnerable to TSA-SQ */
 #define X86_FEATURE_TSA_L1_NO		(21*32+12) /* AMD CPU not vulnerable to TSA-L1 */
 #define X86_FEATURE_CLEAR_CPU_BUF_VM	(21*32+13) /* Clear CPU buffers using VERW before VMRUN */
+#define X86_FEATURE_ABMC		(21*32+14) /* Assignable Bandwidth Monitoring Counters */
 
 /*
  * BUG word(s)

index b4a1f6732a3a..cdd3c3e2d4c6 100644
@@ -50,6 +50,7 @@ static const struct cpuid_bit cpuid_bits[] = {
 	{ X86_FEATURE_MBA,			CPUID_EBX,  6, 0x80000008, 0 },
 	{ X86_FEATURE_SMBA,			CPUID_EBX,  2, 0x80000020, 0 },
 	{ X86_FEATURE_BMEC,			CPUID_EBX,  3, 0x80000020, 0 },
+	{ X86_FEATURE_ABMC,			CPUID_EBX,  5, 0x80000020, 0 },
 	{ X86_FEATURE_TSA_SQ_NO,		CPUID_ECX,  1, 0x80000021, 0 },
 	{ X86_FEATURE_TSA_L1_NO,		CPUID_ECX,  2, 0x80000021, 0 },
 	{ X86_FEATURE_AMD_WORKLOAD_CLASS,	CPUID_EAX, 22, 0x80000021, 0 },

2.34.1

Hi Babu,

Reinette

Add a kernel command-line parameter to enable or disable the exposure of the ABMC (Assignable Bandwidth Monitoring Counters) hardware feature to resctrl.

---
v16: Added Reviewed-by tag.

v15: No changes.

v14: Slight changelog modification.

v13: Removed the Reviewed-by as the file resctrl.rst is moved to
Documentation/filesystems/resctrl.rst. In that sense patch has changed.

v12: No changes.

v11: No changes.

v10: No changes.

v9: No code changes. Added Reviewed-by.

v8: Commit message update.

v7: No changes

v6: No changes

v5: No changes

v4: No changes

v3: No changes

v2: No changes

---
 Documentation/admin-guide/kernel-parameters.txt | 2 +-
 Documentation/filesystems/resctrl.rst           | 1 +
 arch/x86/kernel/cpu/resctrl/core.c              | 2 ++
 3 files changed, 4 insertions(+), 1 deletion(-)

index b29c7a8dc7e6..6a74a32c9416 100644
@@ -6077,7 +6077,7 @@
 	rdt=		[HW,X86,RDT]
 			Turn on/off individual RDT features. List is:
 			cmt, mbmtotal, mbmlocal, l3cat, l3cdp, l2cat, l2cdp,
-			mba, smba, bmec.
+			mba, smba, bmec, abmc.
 			E.g. to turn on cmt and turn off mba use:
 				rdt=cmt,!mba
 

index c7949dd44f2f..c97fd77a107d 100644
@@ -26,6 +26,7 @@ MBM (Memory Bandwidth Monitoring)		"cqm_mbm_total", "cqm_mbm_local"
 MBA (Memory Bandwidth Allocation)		"mba"
 SMBA (Slow Memory Bandwidth Allocation)         ""
 BMEC (Bandwidth Monitoring Event Configuration) ""
+ABMC (Assignable Bandwidth Monitoring Counters) ""
 ===============================================	================================
 
 Historically, new features were made visible by default in /proc/cpuinfo. This

index fbf019c1ff11..b07b12a05886 100644
@@ -711,6 +711,7 @@ enum {
 	RDT_FLAG_MBA,
 	RDT_FLAG_SMBA,
 	RDT_FLAG_BMEC,
+	RDT_FLAG_ABMC,
 };
 
 #define RDT_OPT(idx, n, f)	\

@@ -736,6 +737,7 @@ static struct rdt_options rdt_options[]  __ro_after_init = {
 	RDT_OPT(RDT_FLAG_MBA,	    "mba",	X86_FEATURE_MBA),
 	RDT_OPT(RDT_FLAG_SMBA,	    "smba",	X86_FEATURE_SMBA),
 	RDT_OPT(RDT_FLAG_BMEC,	    "bmec",	X86_FEATURE_BMEC),
+	RDT_OPT(RDT_FLAG_ABMC,	    "abmc",	X86_FEATURE_ABMC),
 };
 #define NUM_RDT_OPTIONS ARRAY_SIZE(rdt_options)
 

2.34.1

The cache allocation and memory bandwidth allocation feature properties are consolidated into struct resctrl_cache and struct resctrl_membw respectively.

In preparation for more monitoring properties that will clobber the existing resource struct more, re-organize the monitoring specific properties to also be in a separate structure.

Also switch "bandwidth sources" term to "memory transactions" to use consistent term within resctrl for related monitoring features.

---
v16: Added the Reviewed-by tag.

v15: Updated changelog.
Minor update in code comment in resctrl.h.

v14: Updated the code comment in resctrl.h.

v13: Changes due to FS/ARCH restructure.

v12: Fixed the conflicts due to recent changes in rdt_resource data structure.
Added new mbm_cfg_mask field to resctrl_mon.
Removed Reviewed-by tag as patch has changed.

v11: No changes.

v10: No changes.

v9: No changes.

v8: Added Reviewed-by from Reinette. No other changes.

v7: Added kernel doc for data structure. Minor text update.

v6: Update commit message and update kernel doc for rdt_resource.

v5: Commit message update.
Also changes related to data structure updates does to SNC support.

v4: New patch.

---
 arch/x86/kernel/cpu/resctrl/core.c    |  4 ++--
 arch/x86/kernel/cpu/resctrl/monitor.c | 10 +++++-----
 fs/resctrl/rdtgroup.c                 |  6 +++---
 include/linux/resctrl.h               | 18 +++++++++++++-----
 4 files changed, 23 insertions(+), 15 deletions(-)

index b07b12a05886..267e9206a999 100644
@@ -107,7 +107,7 @@ u32 resctrl_arch_system_num_rmid_idx(void)
 	struct rdt_resource *r = &rdt_resources_all[RDT_RESOURCE_L3].r_resctrl;
 
 	/* RMID are independent numbers for x86. num_rmid_idx == num_rmid */
-	return r->num_rmid;
+	return r->mon.num_rmid;
 }
 
 struct rdt_resource *resctrl_arch_get_resource(enum resctrl_res_level l)

@@ -541,7 +541,7 @@ static void domain_add_cpu_mon(int cpu, struct rdt_resource *r)
 
 	arch_mon_domain_online(r, d);
 
-	if (arch_domain_mbm_alloc(r->num_rmid, hw_dom)) {
+	if (arch_domain_mbm_alloc(r->mon.num_rmid, hw_dom)) {
 		mon_domain_free(hw_dom);
 		return;
 	}

index f01db2034d08..2558b1bdef8b 100644
@@ -130,7 +130,7 @@ static int logical_rmid_to_physical_rmid(int cpu, int lrmid)
 	if (snc_nodes_per_l3_cache == 1)
 		return lrmid;
 
-	return lrmid + (cpu_to_node(cpu) % snc_nodes_per_l3_cache) * r->num_rmid;
+	return lrmid + (cpu_to_node(cpu) % snc_nodes_per_l3_cache) * r->mon.num_rmid;
 }
 
 static int __rmid_read_phys(u32 prmid, enum resctrl_event_id eventid, u64 *val)

@@ -205,7 +205,7 @@ void resctrl_arch_reset_rmid_all(struct rdt_resource *r, struct rdt_mon_domain *
 			continue;
 		idx = MBM_STATE_IDX(eventid);
 		memset(hw_dom->arch_mbm_states[idx], 0,
-		       sizeof(*hw_dom->arch_mbm_states[0]) * r->num_rmid);
+		       sizeof(*hw_dom->arch_mbm_states[0]) * r->mon.num_rmid);
 	}
 }
 

@@ -344,7 +344,7 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 
 	resctrl_rmid_realloc_limit = boot_cpu_data.x86_cache_size * 1024;
 	hw_res->mon_scale = boot_cpu_data.x86_cache_occ_scale / snc_nodes_per_l3_cache;
-	r->num_rmid = (boot_cpu_data.x86_cache_max_rmid + 1) / snc_nodes_per_l3_cache;
+	r->mon.num_rmid = (boot_cpu_data.x86_cache_max_rmid + 1) / snc_nodes_per_l3_cache;
 	hw_res->mbm_width = MBM_CNTR_WIDTH_BASE;
 
 	if (mbm_offset > 0 && mbm_offset <= MBM_CNTR_WIDTH_OFFSET_MAX)

@@ -359,7 +359,7 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 	 *
 	 * For a 35MB LLC and 56 RMIDs, this is ~1.8% of the LLC.
 	 */
-	threshold = resctrl_rmid_realloc_limit / r->num_rmid;
+	threshold = resctrl_rmid_realloc_limit / r->mon.num_rmid;
 
 	/*
 	 * Because num_rmid may not be a power of two, round the value

@@ -373,7 +373,7 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 
 		/* Detect list of bandwidth sources that can be tracked */
 		cpuid_count(0x80000020, 3, &eax, &ebx, &ecx, &edx);
-		r->mbm_cfg_mask = ecx & MAX_EVT_CONFIG_BITS;
+		r->mon.mbm_cfg_mask = ecx & MAX_EVT_CONFIG_BITS;
 	}
 
 	r->mon_capable = true;

index 77336d5e4915..ca0475b75390 100644
@@ -1135,7 +1135,7 @@ static int rdt_num_rmids_show(struct kernfs_open_file *of,
 {
 	struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
 
-	seq_printf(seq, "%d\n", r->num_rmid);
+	seq_printf(seq, "%d\n", r->mon.num_rmid);
 
 	return 0;
 }

@@ -1731,9 +1731,9 @@ static int mon_config_write(struct rdt_resource *r, char *tok, u32 evtid)
 	}
 
 	/* Value from user cannot be more than the supported set of events */
-	if ((val & r->mbm_cfg_mask) != val) {
+	if ((val & r->mon.mbm_cfg_mask) != val) {
 		rdt_last_cmd_printf("Invalid event configuration: max valid mask is 0x%02x\n",
-				    r->mbm_cfg_mask);
+				    r->mon.mbm_cfg_mask);
 		return -EINVAL;
 	}
 

index 478d7a935ca3..fe2af6cb96d4 100644
@@ -255,38 +255,46 @@ enum resctrl_schema_fmt {
 	RESCTRL_SCHEMA_RANGE,
 };
 
+/**
+ * struct resctrl_mon - Monitoring related data of a resctrl resource.
+ * @num_rmid:		Number of RMIDs available.
+ * @mbm_cfg_mask:	Memory transactions that can be tracked when bandwidth
+ *			monitoring events can be configured.
+ */
+struct resctrl_mon {
+	int			num_rmid;
+	unsigned int		mbm_cfg_mask;
+};
+
 /**
  * struct rdt_resource - attributes of a resctrl resource
  * @rid:		The index of the resource
  * @alloc_capable:	Is allocation available on this machine
  * @mon_capable:	Is monitor feature available on this machine
- * @num_rmid:		Number of RMIDs available
  * @ctrl_scope:		Scope of this resource for control functions
  * @mon_scope:		Scope of this resource for monitor functions
  * @cache:		Cache allocation related data
  * @membw:		If the component has bandwidth controls, their properties.
+ * @mon:		Monitoring related data.
  * @ctrl_domains:	RCU list of all control domains for this resource
  * @mon_domains:	RCU list of all monitor domains for this resource
  * @name:		Name to use in "schemata" file.
  * @schema_fmt:		Which format string and parser is used for this schema.
- * @mbm_cfg_mask:	Bandwidth sources that can be tracked when bandwidth
- *			monitoring events can be configured.
  * @cdp_capable:	Is the CDP feature available on this resource
  */
 struct rdt_resource {
 	int			rid;
 	bool			alloc_capable;
 	bool			mon_capable;
-	int			num_rmid;
 	enum resctrl_scope	ctrl_scope;
 	enum resctrl_scope	mon_scope;
 	struct resctrl_cache	cache;
 	struct resctrl_membw	membw;
+	struct resctrl_mon	mon;
 	struct list_head	ctrl_domains;
 	struct list_head	mon_domains;
 	char			*name;
 	enum resctrl_schema_fmt	schema_fmt;
-	unsigned int		mbm_cfg_mask;
 	bool			cdp_capable;
 };
 

2.34.1

ABMC feature details are reported via CPUID Fn8000_0020_EBX_x5. Bits Description
15:0 MAX_ABMC Maximum Supported Assignable Bandwidth
Monitoring Counter ID + 1

The feature details are documented in APM listed below [1].
[1] AMD64 Architecture Programmer's Manual Volume 2: System Programming Publication # 24593 Revision 3.41 section 19.3.3.3 Assignable Bandwidth Monitoring (ABMC).

Detect the feature and number of assignable counters supported. For backward compatibility, upon detecting the assignable counter feature, enable the mbm_total_bytes and mbm_local_bytes events that users are familiar with as part of original L3 MBM support.

---
v16: Added a new check in get_rdt_mon_resources().
Added a check resctrl_is_mon_event_enabled() before enabling.

v15: Minor update to changelog.
Added check in resctrl_cpu_detect().
Moved the resctrl_enable_mon_event() to resctrl_mon_resource_init().

v14: Updated enumeration to support ABMC regardless of MBM total and local support.
Updated the changelog accordingly.

v13: No changes.

v12: Resolved conflicts because of latest merge.
Removed Reviewed-by as the patch has changed.

v11: No changes.

v10: No changes.

v9: Added Reviewed-by tag. No code changes

v8: Used GENMASK for the mask.

v7: Removed WARN_ON for num_mbm_cntrs. Decided to dynamically allocate the
bitmap. WARN_ON is not required anymore.
Removed redundant comments.

v6: Commit message update.
Renamed abmc_capable to mbm_cntr_assignable.

v5: Name change num_cntrs to num_mbm_cntrs.
Moved abmc_capable to resctrl_mon.

v4: Removed resctrl_arch_has_abmc(). Added all the code inline. We dont
need to separate this as arch code.

v3: Removed changes related to mon_features.
Moved rdt_cpu_has to core.c and added new function resctrl_arch_has_abmc. Also moved the fields mbm_assign_capable and mbm_assign_cntrs to rdt_resource. (James)

v2: Changed the field name to mbm_assign_capable from abmc_capable.

---
 arch/x86/kernel/cpu/resctrl/core.c    |  5 ++++-
 arch/x86/kernel/cpu/resctrl/monitor.c | 11 ++++++++---
 fs/resctrl/monitor.c                  |  7 +++++++
 include/linux/resctrl.h               |  4 ++++
 4 files changed, 23 insertions(+), 4 deletions(-)

index 267e9206a999..09cb5a70b1cb 100644
@@ -883,6 +883,8 @@ static __init bool get_rdt_mon_resources(void)
 		resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
 		ret = true;
 	}
+	if (rdt_cpu_has(X86_FEATURE_ABMC))
+		ret = true;
 
 	if (!ret)
 		return false;

@@ -990,7 +992,8 @@ void resctrl_cpu_detect(struct cpuinfo_x86 *c)
 
 	if (cpu_has(c, X86_FEATURE_CQM_OCCUP_LLC) ||
 	    cpu_has(c, X86_FEATURE_CQM_MBM_TOTAL) ||
-	    cpu_has(c, X86_FEATURE_CQM_MBM_LOCAL)) {
+	    cpu_has(c, X86_FEATURE_CQM_MBM_LOCAL) ||
+	    cpu_has(c, X86_FEATURE_ABMC)) {
 		u32 eax, ebx, ecx, edx;
 
 		/* QoS sub-leaf, EAX=0Fh, ECX=1 */

index 2558b1bdef8b..0a695ce68f46 100644
@@ -339,6 +339,7 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 	unsigned int mbm_offset = boot_cpu_data.x86_cache_mbm_width_offset;
 	struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
 	unsigned int threshold;
+	u32 eax, ebx, ecx, edx;
 
 	snc_nodes_per_l3_cache = snc_get_config();
 

@@ -368,14 +369,18 @@ int __init rdt_get_mon_l3_config(struct rdt_resource *r)
 	 */
 	resctrl_rmid_realloc_threshold = resctrl_arch_round_mon_val(threshold);
 
-	if (rdt_cpu_has(X86_FEATURE_BMEC)) {
-		u32 eax, ebx, ecx, edx;
-
+	if (rdt_cpu_has(X86_FEATURE_BMEC) || rdt_cpu_has(X86_FEATURE_ABMC)) {
 		/* Detect list of bandwidth sources that can be tracked */
 		cpuid_count(0x80000020, 3, &eax, &ebx, &ecx, &edx);
 		r->mon.mbm_cfg_mask = ecx & MAX_EVT_CONFIG_BITS;
 	}
 
+	if (rdt_cpu_has(X86_FEATURE_ABMC)) {
+		r->mon.mbm_cntr_assignable = true;
+		cpuid_count(0x80000020, 5, &eax, &ebx, &ecx, &edx);
+		r->mon.num_mbm_cntrs = (ebx & GENMASK(15, 0)) + 1;
+	}
+
 	r->mon_capable = true;
 
 	return 0;

index dcc6c00eb362..66c8c635f4b3 100644
@@ -924,6 +924,13 @@ int resctrl_mon_resource_init(void)
 	else if (resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID))
 		mba_mbps_default_event = QOS_L3_MBM_TOTAL_EVENT_ID;
 
+	if (r->mon.mbm_cntr_assignable) {
+		if (!resctrl_is_mon_event_enabled(QOS_L3_MBM_TOTAL_EVENT_ID))
+			resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID);
+		if (!resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID))
+			resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
+	}
+
 	return 0;
 }
 

index fe2af6cb96d4..eb80cc233be4 100644
@@ -260,10 +260,14 @@ enum resctrl_schema_fmt {
  * @num_rmid:		Number of RMIDs available.
  * @mbm_cfg_mask:	Memory transactions that can be tracked when bandwidth
  *			monitoring events can be configured.
+ * @num_mbm_cntrs:	Number of assignable counters.
+ * @mbm_cntr_assignable:Is system capable of supporting counter assignment?
  */
 struct resctrl_mon {
 	int			num_rmid;
 	unsigned int		mbm_cfg_mask;
+	int			num_mbm_cntrs;
+	bool			mbm_cntr_assignable;
 };
 
 /**

2.34.1

Hi Babu,

...

	if (!cpu_has(c, X86_FEATURE_CQM_LLC) && !cpu_has(c, X86_FEATURE_ABMC)) {
		...
		return;
	}

	resctrl_mon_resource_init() {
		...
		mon_event_all[QOS_L3_MBM_TOTAL_EVENT_ID].evt_cfg = MAX_EVT_CONFIG_BITS;
		mon_event_all[QOS_L3_MBM_LOCAL_EVENT_ID].evt_cfg = READS_TO_LOCAL_MEM |
								   READS_TO_LOCAL_S_MEM |
								   NON_TEMP_WRITE_TO_LOCAL_MEM;
		...
	}

Hi Reinette,

Sure. Added now.

That is correct.
Changed the assignment.

mon_event_all[QOS_L3_MBM_TOTAL_EVENT_ID].evt_cfg = r->mon.mbm_cfg_mask; mon_event_all[QOS_L3_MBM_LOCAL_EVENT_ID].evt_cfg = r->mon.mbm_cfg_mask & (READS_TO_LOCAL_MEM | READS_TO_LOCAL_S_MEM | NON_TEMP_WRITE_TO_LOCAL_MEM);

Yes. Sure.

Thanks
Babu Moger

Add the functionality to enable/disable AMD ABMC feature.

AMD ABMC feature is enabled by setting enabled bit(0) in MSR L3_QOS_EXT_CFG. When the state of ABMC is changed, the MSR needs to be updated on all the logical processors in the QOS Domain.

Hardware counters will reset when ABMC state is changed.

The ABMC feature details are documented in APM listed below [1].
[1] AMD64 Architecture Programmer's Manual Volume 2: System Programming Publication # 24593 Revision 3.41 section 19.3.3.3 Assignable Bandwidth Monitoring (ABMC).

---
v16: Added Reviewed-by tag.

v15: Minor comment change in resctrl.h.

v14: Added lockdep_assert_cpus_held() in _resctrl_abmc_enable().
Removed inline for resctrl_arch_mbm_cntr_assign_enabled(). Added prototype descriptions for resctrl_arch_mbm_cntr_assign_enabled() and resctrl_arch_mbm_cntr_assign_set() in include/linux/resctrl.h.

v13: Resolved minor conflicts with recent FS/ARCH restructure.

v12: Clarified the comment on _resctrl_abmc_enable().
Added the code to reset arch state in _resctrl_abmc_enable(). Resolved the conflicts with latest merge.

v11: Moved the monitoring related calls to monitor.c file.
Moved the changes from include/linux/resctrl.h to arch/x86/kernel/cpu/resctrl/internal.h. Removed the Reviewed-by tag as patch changed. Actual code did not change.

v10: No changes.

v9: Re-ordered the MSR and added Reviewed-by tag.

v8: Commit message update and moved around the comments about L3_QOS_EXT_CFG
to _resctrl_abmc_enable.

v7: Renamed the function
resctrl_arch_get_abmc_enabled() to resctrl_arch_mbm_cntr_assign_enabled().

Merged resctrl_arch_mbm_cntr_assign_disable, resctrl_arch_mbm_cntr_assign_disable and renamed to resctrl_arch_mbm_cntr_assign_set().

Moved the function definition to linux/resctrl.h.

Passed the struct rdt_resource to these functions.
Removed resctrl_arch_reset_rmid_all() from arch code. This will be done from the caller.

v6: Renamed abmc_enabled to mbm_cntr_assign_enabled.
Used msr_set_bit and msr_clear_bit for msr updates.
Renamed resctrl_arch_abmc_enable() to resctrl_arch_mbm_cntr_assign_enable(). Renamed resctrl_arch_abmc_disable() to resctrl_arch_mbm_cntr_assign_disable(). Made _resctrl_abmc_enable to return void.

v5: Renamed resctrl_abmc_enable to resctrl_arch_abmc_enable.
Renamed resctrl_abmc_disable to resctrl_arch_abmc_disable. Introduced resctrl_arch_get_abmc_enabled to get abmc state from non-arch code.
Renamed resctrl_abmc_set_all to _resctrl_abmc_enable(). Modified commit log to make it clear about AMD ABMC feature.

v3: No changes.

v2: Few text changes in commit message.

---
 arch/x86/include/asm/msr-index.h       |  1 +
 arch/x86/kernel/cpu/resctrl/internal.h |  5 +++
 arch/x86/kernel/cpu/resctrl/monitor.c  | 45 ++++++++++++++++++++++++++
 include/linux/resctrl.h                | 20 ++++++++++++
 4 files changed, 71 insertions(+)

index 7490bb5c0776..c998cf0e1375 100644
@@ -1222,6 +1222,7 @@
 /* - AMD: */
 #define MSR_IA32_MBA_BW_BASE		0xc0000200
 #define MSR_IA32_SMBA_BW_BASE		0xc0000280
+#define MSR_IA32_L3_QOS_EXT_CFG		0xc00003ff
 #define MSR_IA32_EVT_CFG_BASE		0xc0000400
 
 /* AMD-V MSRs */

index 58dca892a5df..a79a487e639c 100644
@@ -37,6 +37,9 @@ struct arch_mbm_state {
 	u64	prev_msr;
 };
 
+/* Setting bit 0 in L3_QOS_EXT_CFG enables the ABMC feature. */
+#define ABMC_ENABLE_BIT			0
+
 /**
  * struct rdt_hw_ctrl_domain - Arch private attributes of a set of CPUs that share
  *			       a resource for a control function

@@ -102,6 +105,7 @@ struct msr_param {
  * @mon_scale:		cqm counter * mon_scale = occupancy in bytes
  * @mbm_width:		Monitor width, to detect and correct for overflow.
  * @cdp_enabled:	CDP state of this resource
+ * @mbm_cntr_assign_enabled:	ABMC feature is enabled
  *
  * Members of this structure are either private to the architecture
  * e.g. mbm_width, or accessed via helpers that provide abstraction. e.g.

@@ -115,6 +119,7 @@ struct rdt_hw_resource {
 	unsigned int		mon_scale;
 	unsigned int		mbm_width;
 	bool			cdp_enabled;
+	bool			mbm_cntr_assign_enabled;
 };
 
 static inline struct rdt_hw_resource *resctrl_to_arch_res(struct rdt_resource *r)

index eb80cc233be4..919806122c50 100644
@@ -445,6 +445,26 @@ static inline u32 resctrl_get_config_index(u32 closid,
 bool resctrl_arch_get_cdp_enabled(enum resctrl_res_level l);
 int resctrl_arch_set_cdp_enabled(enum resctrl_res_level l, bool enable);
 
+/**
+ * resctrl_arch_mbm_cntr_assign_enabled() - Check if MBM counter assignment
+ *					    mode is enabled.
+ * @r:		Pointer to the resource structure.
+ *
+ * Return:
+ * true if the assignment mode is enabled, false otherwise.
+ */
+bool resctrl_arch_mbm_cntr_assign_enabled(struct rdt_resource *r);
+
+/**
+ * resctrl_arch_mbm_cntr_assign_set() - Configure the MBM counter assignment mode.
+ * @r:		Pointer to the resource structure.
+ * @enable:	Set to true to enable, false to disable the assignment mode.
+ *
+ * Return:
+ * 0 on success, < 0 on error.
+ */
+int resctrl_arch_mbm_cntr_assign_set(struct rdt_resource *r, bool enable);
+
 /*
  * Update the ctrl_val and apply this config right now.
  * Must be called on one of the domain's CPUs.

2.34.1

Introduce the resctrl file "mbm_assign_mode" to list the supported counter assignment modes.

The "mbm_event" counter assignment mode allows users to assign a hardware counter to an RMID, event pair and monitor bandwidth usage as long as it is assigned. The hardware continues to track the assigned counter until it is explicitly unassigned by the user. Each event within a resctrl group can be assigned independently in this mode.

On AMD systems "mbm_event" mode is backed by the ABMC (Assignable Bandwidth Monitoring Counters) hardware feature and is enabled by default.

The "default" mode is the existing mode that works without the explicit counter assignment, instead relying on dynamic counter assignment by hardware that may result in hardware not dedicating a counter resulting in monitoring data reads returning "Unavailable".

Provide an interface to display the monitor modes on the system.

$ cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
[mbm_event]
default

Add IS_ENABLED(CONFIG_RESCTRL_ASSIGN_FIXED) check to support Arm64.

On x86, CONFIG_RESCTRL_ASSIGN_FIXED is not defined. On Arm64, it will be defined when the "mbm_event" mode is supported.

Add IS_ENABLED(CONFIG_RESCTRL_ASSIGN_FIXED) check early to ensure the user interface remains compatible with upcoming Arm64 support. IS_ENABLED() safely evaluates to 0 when the configuration is not defined.

As a result, for MPAM, the display would be either:
[default]
or
[mbm_event]

---
v16: Update with Reviewed-by tag.

v15: Minor text changes in changelog and resctrl.rst.

v14: Changed the name of the monitor mode to mbm_cntr_evt_assign based on the discussion.
https://lore.kernel.org/lkml/[email protected]/
Changed the name of the mbm_assign_mode's.
Updated resctrl.rst for mbm_event mode.
Changed subject line to fs/resctrl.

v13: Updated the commit log with motivation for adding CONFIG_RESCTRL_ASSIGN_FIXED.
Added fflag RFTYPE_RES_CACHE for mbm_assign_mode file.
Updated user doc. Removed the references to "mbm_assign_control". Resolved the conflicts with latest FS/ARCH code restructure.

v12: Minor text update in change log and user documentation.
Added the check CONFIG_RESCTRL_ASSIGN_FIXED to take care of arm platforms. This will be defined only in arm and not in x86.

v11: Renamed rdtgroup_mbm_assign_mode_show() to resctrl_mbm_assign_mode_show().
Removed few texts in resctrl.rst about AMD specific information. Updated few texts.

v10: Added few more text to user documentation clarify on the default mode.

v9: Updated user documentation based on comments.

v8: Commit message update.

v7: Updated the descriptions/commit log in resctrl.rst to generic text.
Thanks to James and Reinette.
Rename mbm_mode to mbm_assign_mode.
Introduced mutex lock in rdtgroup_mbm_mode_show().

v6: Added documentation for mbm_cntr_assign and legacy mode.
Moved mbm_mode fflags initialization to static initialization.

v5: Changed interface name to mbm_mode.
It will be always available even if ABMC feature is not supported. Added description in resctrl.rst about ABMC mode.
Fixed display abmc and legacy consistantly.

v4: Fixed the checks for legacy and abmc mode. Default it ABMC.

v3: New patch to display ABMC capability.

---
 Documentation/filesystems/resctrl.rst | 31 ++++++++++++++++++++++
 fs/resctrl/rdtgroup.c                 | 37 +++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

index c97fd77a107d..b692829fec5f 100644
@@ -257,6 +257,37 @@ with the following files:
 	    # cat /sys/fs/resctrl/info/L3_MON/mbm_local_bytes_config
 	    0=0x30;1=0x30;3=0x15;4=0x15
 
+"mbm_assign_mode":
+	The supported counter assignment modes. The enclosed brackets indicate which mode
+	is enabled.
+	::
+
+	  # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode
+	  [mbm_event]
+	  default
+
+	"mbm_event":
+
+	mbm_event mode allows users to assign a hardware counter to an RMID, event
+	pair and monitor the bandwidth usage as long as it is assigned. The hardware
+	continues to track the assigned counter until it is explicitly unassigned by
+	the user. Each event within a resctrl group can be assigned independently.
+
+	In this mode, a monitoring event can only accumulate data while it is backed
+	by a hardware counter. Use "mbm_L3_assignments" found in each CTRL_MON and MON
+	group to specify which of the events should have a counter assigned. The number
+	of counters available is described in the "num_mbm_cntrs" file. Changing the
+	mode may cause all counters on the resource to reset.
+
+	"default":
+
+	In default mode, resctrl assumes there is a hardware counter for each
+	event within every CTRL_MON and MON group. On AMD platforms, it is
+	recommended to use the mbm_event mode, if supported, to prevent reset of MBM
+	events between reads resulting from hardware re-allocating counters. This can
+	result in misleading values or display "Unavailable" if no counter is assigned
+	to the event.
+
 "max_threshold_occupancy":
 		Read/write file provides the largest value (in
 		bytes) at which a previously used LLC_occupancy

index ca0475b75390..c7ca9113a12a 100644
@@ -1799,6 +1799,36 @@ static ssize_t mbm_local_bytes_config_write(struct kernfs_open_file *of,
 	return ret ?: nbytes;
 }
 
+static int resctrl_mbm_assign_mode_show(struct kernfs_open_file *of,
+					struct seq_file *s, void *v)
+{
+	struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
+	bool enabled;
+
+	mutex_lock(&rdtgroup_mutex);
+	enabled = resctrl_arch_mbm_cntr_assign_enabled(r);
+
+	if (r->mon.mbm_cntr_assignable) {
+		if (enabled)
+			seq_puts(s, "[mbm_event]\n");
+		else
+			seq_puts(s, "[default]\n");
+
+		if (!IS_ENABLED(CONFIG_RESCTRL_ASSIGN_FIXED)) {
+			if (enabled)
+				seq_puts(s, "default\n");
+			else
+				seq_puts(s, "mbm_event\n");
+		}
+	} else {
+		seq_puts(s, "[default]\n");
+	}
+
+	mutex_unlock(&rdtgroup_mutex);
+
+	return 0;
+}
+
 /* rdtgroup information files for one cache resource. */
 static struct rftype res_common_files[] = {
 	{

@@ -1911,6 +1941,13 @@ static struct rftype res_common_files[] = {
 		.seq_show	= mbm_local_bytes_config_show,
 		.write		= mbm_local_bytes_config_write,
 	},
+	{
+		.name		= "mbm_assign_mode",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= resctrl_mbm_assign_mode_show,
+		.fflags		= RFTYPE_MON_INFO | RFTYPE_RES_CACHE,
+	},
 	{
 		.name		= "cpus",
 		.mode		= 0644,

2.34.1

Hi Reinette,

Thanks
Babu Moger

Hi Babu,

I agree. monitor.c is appropriate for this code.

Reinette

The "mbm_event" counter assignment mode allows users to assign a hardware counter to an RMID, event pair and monitor bandwidth usage as long as it is assigned. The hardware continues to track the assigned counter until it is explicitly unassigned by the user.

Create 'num_mbm_cntrs' resctrl file that displays the number of counters supported in each domain. 'num_mbm_cntrs' is only visible to user space when the system supports "mbm_event" mode.

---
v16: Added Reviewed-by tag.

v15: Changed "assign a hardware counter ID" to "assign a hardware counter"
in couple of places.

v14: Minor update to changelog and user doc (resctrl.rst).
Changed subject line to fs/resctrl.

v13: Updated the changelog.
Added fflags RFTYPE_RES_CACHE to the file num_mbm_cntrs.
Replaced seq_puts from seq_putc where applicable.
Resolved conflicts caused by the recent FS/ARCH code restructure. The files monitor.c/rdtgroup.c have been split between FS and ARCH directories.

v12: Changed the code to display the max supported monitoring counters in
each domain. Also updated the documentation.
Resolved the conflict with the latest code.

v11: Renamed rdtgroup_num_mbm_cntrs_show() to resctrl_num_mbm_cntrs_show().
Few monor text updates.

v10: No changes.

v9: Updated user document based on the comments.
Will add a new file available_mbm_cntrs later in the series.

v8: Commit message update and documentation update.

v7: Minor commit log text changes.

v6: No changes.

v5: Changed the display name from num_cntrs to num_mbm_cntrs.
Updated the commit message.
Moved the patch after mbm_mode is introduced.

v4: Changed the counter name to num_cntrs. And few text changes.

v3: Changed the field name to mbm_assign_cntrs.

v2: Changed the field name to mbm_assignable_counters from abmc_counter.

---
 Documentation/filesystems/resctrl.rst | 11 ++++++++++
 fs/resctrl/monitor.c                  |  2 ++
 fs/resctrl/rdtgroup.c                 | 30 +++++++++++++++++++++++++++
 3 files changed, 43 insertions(+)

index b692829fec5f..4eb27530be6f 100644
@@ -288,6 +288,17 @@ with the following files:
 	result in misleading values or display "Unavailable" if no counter is assigned
 	to the event.
 
+"num_mbm_cntrs":
+	The maximum number of counters (total of available and assigned counters) in
+	each domain when the system supports mbm_event mode.
+
+	For example, on a system with maximum of 32 memory bandwidth monitoring
+	counters in each of its L3 domains:
+	::
+
+	  # cat /sys/fs/resctrl/info/L3_MON/num_mbm_cntrs
+	  0=32;1=32
+
 "max_threshold_occupancy":
 		Read/write file provides the largest value (in
 		bytes) at which a previously used LLC_occupancy

index 66c8c635f4b3..4539b08db7b9 100644
@@ -929,6 +929,8 @@ int resctrl_mon_resource_init(void)
 			resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID);
 		if (!resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID))
 			resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
+		resctrl_file_fflags_init("num_mbm_cntrs",
+					 RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
 	}
 
 	return 0;

index c7ca9113a12a..acbda73a9b9d 100644
@@ -1829,6 +1829,30 @@ static int resctrl_mbm_assign_mode_show(struct kernfs_open_file *of,
 	return 0;
 }
 
+static int resctrl_num_mbm_cntrs_show(struct kernfs_open_file *of,
+				      struct seq_file *s, void *v)
+{
+	struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
+	struct rdt_mon_domain *dom;
+	bool sep = false;
+
+	cpus_read_lock();
+	mutex_lock(&rdtgroup_mutex);
+
+	list_for_each_entry(dom, &r->mon_domains, hdr.list) {
+		if (sep)
+			seq_putc(s, ';');
+
+		seq_printf(s, "%d=%d", dom->hdr.id, r->mon.num_mbm_cntrs);
+		sep = true;
+	}
+	seq_putc(s, '\n');
+
+	mutex_unlock(&rdtgroup_mutex);
+	cpus_read_unlock();
+	return 0;
+}
+
 /* rdtgroup information files for one cache resource. */
 static struct rftype res_common_files[] = {
 	{

@@ -1866,6 +1890,12 @@ static struct rftype res_common_files[] = {
 		.seq_show	= rdt_default_ctrl_show,
 		.fflags		= RFTYPE_CTRL_INFO | RFTYPE_RES_CACHE,
 	},
+	{
+		.name		= "num_mbm_cntrs",
+		.mode		= 0444,
+		.kf_ops		= &rdtgroup_kf_single_ops,
+		.seq_show	= resctrl_num_mbm_cntrs_show,
+	},
 	{
 		.name		= "min_cbm_bits",
 		.mode		= 0444,

2.34.1

Hi Reinette,

Thanks
Babu Moger

Hi Babu,

Yes, this sounds good to me. This is what I had in mind when suggesting in [1] that the monitoring related handlers should be located in monitor.c

Reinette

[1] https://lore.kernel.org/lkml/[email protected]/

The "mbm_event" counter assignment mode allows users to assign a hardware counter to an RMID, event pair and monitor bandwidth usage as long as it is assigned. The hardware continues to track the assigned counter until it is explicitly unassigned by the user. Counters are assigned/unassigned at monitoring domain level.

Manage a monitoring domain's hardware counters using a per monitoring domain array of struct mbm_cntr_cfg that is indexed by the hardware counter ID. A hardware counter's configuration contains the MBM event ID and points to the monitoring group that it is assigned to, with a NULL pointer meaning that the hardware counter is available for assignment.

There is no direct way to determine which hardware counters are assigned to a particular monitoring group. Check every entry of every hardware counter configuration array in every monitoring domain to query which MBM events of a monitoring group is tracked by hardware. Such queries are acceptable because of a very small number of assignable counters (32 to 64).

---
v16: Added Reviewed-by tag.

v15: Minor changelog update.
Removed evt_cfg from struct mbm_cntr_cfg based on the discussion.
https://lore.kernel.org/lkml/[email protected]/

v14: Updated code documentation and changelog.
Fixed up the indentation in resctrl.h.
Changed subject line to fs/resctrl.

v13: Resolved conflicts caused by the recent FS/ARCH code restructure.
The files monitor.c/rdtgroup.c have been split between FS and ARCH directories.

v12: Fixed the struct mbm_cntr_cfg code documentation.
Removed few strange charactors in changelog.
Added the counter range for better understanding. Moved the struct mbm_cntr_cfg definition to resctrl/internal.h as suggested by James.

v11: Refined the change log based on Reinette's feedback.
Fixed few style issues.

v10: Patch changed completely to handle the counters at domain level.
https://lore.kernel.org/lkml/CALPaoCj+zWq1vkHVbXYP0znJbe6Ke3PXPWjtri5AFgD9cQDCUg@mail.gmail.com/
Removed Reviewed-by tag.
Did not see the need to add cntr_id in mbm_state structure. Not used in the code.

v9: Added Reviewed-by tag. No other changes.

v8: Minor commit message changes.

v7: Added check mbm_cntr_assignable for allocating bitmap mbm_cntr_map

v6: New patch to add domain level assignment.

---
 fs/resctrl/rdtgroup.c   |  8 ++++++++
 include/linux/resctrl.h | 15 +++++++++++++++
 2 files changed, 23 insertions(+)

index acbda73a9b9d..a09566720d4f 100644
@@ -4086,6 +4086,7 @@ static void domain_destroy_mon_state(struct rdt_mon_domain *d)
 {
 	int idx;
 
+	kfree(d->cntr_cfg);
 	bitmap_free(d->rmid_busy_llc);
 	for_each_mbm_idx(idx) {
 		kfree(d->mbm_states[idx]);

@@ -4169,6 +4170,13 @@ static int domain_setup_mon_state(struct rdt_resource *r, struct rdt_mon_domain
 			goto cleanup;
 	}
 
+	if (resctrl_is_mbm_enabled() && r->mon.mbm_cntr_assignable) {
+		tsize = sizeof(*d->cntr_cfg);
+		d->cntr_cfg = kcalloc(r->mon.num_mbm_cntrs, tsize, GFP_KERNEL);
+		if (!d->cntr_cfg)
+			goto cleanup;
+	}
+
 	return 0;
 cleanup:
 	bitmap_free(d->rmid_busy_llc);

index 919806122c50..e013caba6641 100644
@@ -156,6 +156,18 @@ struct rdt_ctrl_domain {
 	u32				*mbps_val;
 };
 
+/**
+ * struct mbm_cntr_cfg - Assignable counter configuration.
+ * @evtid:		MBM event to which the counter is assigned. Only valid
+ *			if @rdtgroup is not NULL.
+ * @rdtgrp:		resctrl group assigned to the counter. NULL if the
+ *			counter is free.
+ */
+struct mbm_cntr_cfg {
+	enum resctrl_event_id	evtid;
+	struct rdtgroup		*rdtgrp;
+};
+
 /**
  * struct rdt_mon_domain - group of CPUs sharing a resctrl monitor resource
  * @hdr:		common header for different domain types

@@ -168,6 +180,8 @@ struct rdt_ctrl_domain {
  * @cqm_limbo:		worker to periodically read CQM h/w counters
  * @mbm_work_cpu:	worker CPU for MBM h/w counters
  * @cqm_work_cpu:	worker CPU for CQM h/w counters
+ * @cntr_cfg:		array of assignable counters' configuration (indexed
+ *			by counter ID)
  */
 struct rdt_mon_domain {
 	struct rdt_domain_hdr		hdr;

@@ -178,6 +192,7 @@ struct rdt_mon_domain {
 	struct delayed_work		cqm_limbo;
 	int				mbm_work_cpu;
 	int				cqm_work_cpu;
+	struct mbm_cntr_cfg		*cntr_cfg;
 };
 
 /**

2.34.1

Introduce the "available_mbm_cntrs" resctrl file to display the number of counters available for assignment in each domain when "mbm_event" mode is enabled.

---
v16: Added Reviewed-by tag.

v15: Minor changelog text update.
Minor resctrl.rst text update and corrected the error text in resctrl_available_mbm_cntrs_show().
Changed the goto label to out_unlock for consistency.

v14: Minor changelog update.
Changed subject line to fs/resctrl.

v13: Resolved conflicts caused by the recent FS/ARCH code restructure.
The files monitor.c and rdtgroup.c file has now been split between the FS and ARCH directories.

v12: Minor change to change log.
Updated the documentation text with an example.
Replaced seq_puts(s, ";") with seq_putc(s, ';');
Added missing rdt_last_cmd_clear() in resctrl_available_mbm_cntrs_show().

v11: Rename rdtgroup_available_mbm_cntrs_show() to resctrl_available_mbm_cntrs_show().
Few minor text changes.

v10: Patch changed to handle the counters at domain level.
https://lore.kernel.org/lkml/CALPaoCj+zWq1vkHVbXYP0znJbe6Ke3PXPWjtri5AFgD9cQDCUg@mail.gmail.com/
So, display logic also changed now.

v9: New patch

---
 Documentation/filesystems/resctrl.rst | 11 ++++++
 fs/resctrl/monitor.c                  |  2 ++
 fs/resctrl/rdtgroup.c                 | 48 +++++++++++++++++++++++++++
 3 files changed, 61 insertions(+)

index 4eb27530be6f..446736dbd97f 100644
@@ -299,6 +299,17 @@ with the following files:
 	  # cat /sys/fs/resctrl/info/L3_MON/num_mbm_cntrs
 	  0=32;1=32
 
+"available_mbm_cntrs":
+	The number of counters available for assignment in each domain when mbm_event
+	mode is enabled on the system.
+
+	For example, on a system with 30 available [hardware] assignable counters
+	in each of its L3 domains:
+	::
+
+	  # cat /sys/fs/resctrl/info/L3_MON/available_mbm_cntrs
+	  0=30;1=30
+
 "max_threshold_occupancy":
 		Read/write file provides the largest value (in
 		bytes) at which a previously used LLC_occupancy

index 4539b08db7b9..a0b0ea45c7b4 100644
@@ -931,6 +931,8 @@ int resctrl_mon_resource_init(void)
 			resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
 		resctrl_file_fflags_init("num_mbm_cntrs",
 					 RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
+		resctrl_file_fflags_init("available_mbm_cntrs",
+					 RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
 	}
 
 	return 0;

2.34.1

Hi Reinette,

Thanks
Babu Moger

Hi Babu,

Yes, I believe monitor.c is most appropriate for all the monitoring related handlers [1].

Reinette

[1] https://lore.kernel.org/lkml/[email protected]/

Hi Reinette,

Sure. Will do.

Thanks
Babu Moger

The ABMC feature allows users to assign a hardware counter to an RMID, event pair and monitor bandwidth usage as long as it is assigned. The hardware continues to track the assigned counter until it is explicitly unassigned by the user.

The ABMC feature implements an MSR L3_QOS_ABMC_CFG (C000_03FDh). ABMC counter assignment is done by setting the counter id, bandwidth source (RMID) and bandwidth configuration.

Attempts to read or write the MSR when ABMC is not enabled will result in a #GP(0) exception.

Introduce the data structures and definitions for MSR L3_QOS_ABMC_CFG (0xC000_03FDh):
=========================================================================
Bits Mnemonic Description Access Reset
Type Value
=========================================================================
63 CfgEn Configuration Enable R/W 0

62 CtrEn Enable/disable counting R/W 0

61:53 – Reserved MBZ 0

52:48 CtrID Counter Identifier R/W 0

47 IsCOS BwSrc field is a CLOSID R/W 0
(not an RMID)

46:44 – Reserved MBZ 0

43:32 BwSrc Bandwidth Source R/W 0
(RMID or CLOSID)

31:0 BwType Bandwidth configuration R/W 0
tracked by the CtrID
==========================================================================

The feature details are documented in the APM listed below [1].
[1] AMD64 Architecture Programmer's Manual Volume 2: System Programming Publication # 24593 Revision 3.41 section 19.3.3.3 Assignable Bandwidth Monitoring (ABMC).

---
v16: Added Reviewed-by tag.

v15: Minor changelog update.

v14: Removed BMEC reference internal.h.
Updated the changelog and code documentation.

v13: Removed the Reviewed-by tag as there is commit log change to remove
BMEC reference.

v12: No changes.

v11: No changes.

v10: No changes.

v9: Removed the references of L3_QOS_ABMC_DSC.
Text changes about configuration in kernel doc.

v8: Update the configuration notes in kernel_doc.
Few commit message update.

v7: Removed the reference of L3_QOS_ABMC_DSC as it is not used anymore.
Moved the configuration notes to kernel_doc.
Adjusted the tabs for l3_qos_abmc_cfg and checkpatch seems happy.

v6: Removed all the fs related changes.
Added note on CfgEn,CtrEn.
Removed the definitions which are not used.
Removed cntr_id initialization.

v5: Moved assignment flags here (path 10/19 of v4).
Added MON_CNTR_UNSET definition to initialize cntr_id's. More details in commit log.
Renamed few fields in l3_qos_abmc_cfg for readability.

v4: Added more descriptions.
Changed the name abmc_ctr_id to ctr_id.
Added L3_QOS_ABMC_DSC. Used for reading the configuration.

v3: No changes.

v2: No changes.

---
 arch/x86/include/asm/msr-index.h       |  1 +
 arch/x86/kernel/cpu/resctrl/internal.h | 36 ++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

index c998cf0e1375..3ad7f37b8ad8 100644
@@ -1222,6 +1222,7 @@
 /* - AMD: */
 #define MSR_IA32_MBA_BW_BASE		0xc0000200
 #define MSR_IA32_SMBA_BW_BASE		0xc0000280
+#define MSR_IA32_L3_QOS_ABMC_CFG	0xc00003fd
 #define MSR_IA32_L3_QOS_EXT_CFG		0xc00003ff
 #define MSR_IA32_EVT_CFG_BASE		0xc0000400
 

index a79a487e639c..6bf6042f11b6 100644
@@ -164,6 +164,42 @@ union cpuid_0x10_x_edx {
 	unsigned int full;
 };
 
+/*
+ * ABMC counters are configured by writing to L3_QOS_ABMC_CFG.
+ *
+ * @bw_type		: Event configuration that represent the memory
+ *			  transactions being tracked by the @cntr_id.
+ * @bw_src		: Bandwidth source (RMID or CLOSID).
+ * @reserved1		: Reserved.
+ * @is_clos		: @bw_src field is a CLOSID (not an RMID).
+ * @cntr_id		: Counter identifier.
+ * @reserved		: Reserved.
+ * @cntr_en		: Counting enable bit.
+ * @cfg_en		: Configuration enable bit.
+ *
+ * Configuration and counting:
+ * Counter can be configured across multiple writes to MSR. Configuration
+ * is applied only when @cfg_en = 1. Counter @cntr_id is reset when the
+ * configuration is applied.
+ * @cfg_en = 1, @cntr_en = 0 : Apply @cntr_id configuration but do not
+ *                             count events.
+ * @cfg_en = 1, @cntr_en = 1 : Apply @cntr_id configuration and start
+ *                             counting events.
+ */
+union l3_qos_abmc_cfg {
+	struct {
+		unsigned long bw_type  :32,
+			      bw_src   :12,
+			      reserved1: 3,
+			      is_clos  : 1,
+			      cntr_id  : 5,
+			      reserved : 9,
+			      cntr_en  : 1,
+			      cfg_en   : 1;
+	} split;
+	unsigned long full;
+};
+
 void rdt_ctrl_update(void *arg);
 
 int rdt_get_mon_l3_config(struct rdt_resource *r);

2.34.1

When supported, mbm_event counter assignment mode allows the user to configure events to track specific types of memory transactions.

Introduce the evt_cfg field in struct mon_evt to define the type of memory transactions tracked by a monitoring event. Also add a helper function to get the evt_cfg value.

---
v16: Added Reviewed-by tag.

v15: Updated the changelog.
Removed resctrl_set_mon_evt_cfg().
Moved the event initialization to resctrl_mon_resource_init().

v14: This is updated patch from previous patch.
https://lore.kernel.org/lkml/95b7f4e9d72773e8fda327fc80b429646efc3a8a.1747349530.git.babu.moger@amd.com/
Removed mbm_mode as it is not required anymore. Added resctrl_get_mon_evt_cfg() and resctrl_set_mon_evt_cfg().

v13: New patch to handle different event configuration types with
mbm_cntr_assign mode.

---
 fs/resctrl/internal.h   | 5 +++++
 fs/resctrl/monitor.c    | 9 +++++++++
 include/linux/resctrl.h | 2 ++
 3 files changed, 16 insertions(+)

index 4f315b7e9ec0..db3a0f12ad77 100644
@@ -56,6 +56,10 @@ static inline struct rdt_fs_context *rdt_fc2context(struct fs_context *fc)
  * @evtid:		event id
  * @rid:		resource id for this event
  * @name:		name of the event
+ * @evt_cfg:		Event configuration value that represents the
+ *			memory transactions (e.g., READS_TO_LOCAL_MEM,
+ *			READS_TO_REMOTE_MEM) being tracked by @evtid.
+ *			Only valid if @evtid is an MBM event.
  * @configurable:	true if the event is configurable
  * @enabled:		true if the event is enabled
  */

@@ -63,6 +67,7 @@ struct mon_evt {
 	enum resctrl_event_id	evtid;
 	enum resctrl_res_level	rid;
 	char			*name;
+	u32			evt_cfg;
 	bool			configurable;
 	bool			enabled;
 };

index a0b0ea45c7b4..a089867262fa 100644
@@ -884,6 +884,11 @@ bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid)
 	       mon_event_all[eventid].enabled;
 }
 
+u32 resctrl_get_mon_evt_cfg(enum resctrl_event_id evtid)
+{
+	return mon_event_all[evtid].evt_cfg;
+}
+
 /**
  * resctrl_mon_resource_init() - Initialise global monitoring structures.
  *

@@ -929,6 +934,10 @@ int resctrl_mon_resource_init(void)
 			resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID);
 		if (!resctrl_is_mon_event_enabled(QOS_L3_MBM_LOCAL_EVENT_ID))
 			resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
+		mon_event_all[QOS_L3_MBM_TOTAL_EVENT_ID].evt_cfg = MAX_EVT_CONFIG_BITS;
+		mon_event_all[QOS_L3_MBM_LOCAL_EVENT_ID].evt_cfg = READS_TO_LOCAL_MEM |
+								   READS_TO_LOCAL_S_MEM |
+								   NON_TEMP_WRITE_TO_LOCAL_MEM;
 		resctrl_file_fflags_init("num_mbm_cntrs",
 					 RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
 		resctrl_file_fflags_init("available_mbm_cntrs",

index e013caba6641..87daa4ca312d 100644
@@ -409,6 +409,8 @@ static inline bool resctrl_is_mbm_event(enum resctrl_event_id eventid)
 		eventid <= QOS_L3_MBM_LOCAL_EVENT_ID);
 }
 
+u32 resctrl_get_mon_evt_cfg(enum resctrl_event_id eventid);
+
 /* Iterate over all memory bandwidth events */
 #define for_each_mbm_event_id(eventid)				\
 	for (eventid = QOS_L3_MBM_TOTAL_EVENT_ID;		\

2.34.1

The ABMC feature allows users to assign a hardware counter to an RMID, event pair and monitor bandwidth usage as long as it is assigned. The hardware continues to track the assigned counter until it is explicitly unassigned by the user.

Implement an x86 architecture-specific handler to configure a counter. This architecture specific handler is called by resctrl fs when a counter is assigned or unassigned as well as when an already assigned counter's configuration should be updated. Configure counters by writing to the L3_QOS_ABMC_CFG MSR, specifying the counter ID, bandwidth source (RMID), and event configuration.

The feature details are documented in the APM listed below [1].
[1] AMD64 Architecture Programmer's Manual Volume 2: System Programming

    Publication # 24593 Revision 3.41 section 19.3.3.3 Assignable Bandwidth
    Monitoring (ABMC).

---
v16: Updated the changelog.
Reset the architectural state in resctrl_arch_config_cntr() in both assign and unassign cases.

v15: Minor changelog update.
Added few code comments in include/linux/resctrl.h.

v14: Removed evt_cfg parameter in resctrl_arch_config_cntr(). Get evt_cfg
only when assign is required.
Minor update to changelog.

v13: Moved resctrl_arch_config_cntr() prototype to include/linux/resctrl.h.
Changed resctrl_arch_config_cntr() to retun void from int. Updated the kernal doc for the prototype.
Updated the code comment.

12: Added the check to reset the architecture-specific state only when
assign is requested.
Added evt_cfg as the parameter as the user will be passing the event configuration from /info/L3_MON/event_configs/.

v11: Moved resctrl_arch_assign_cntr() and resctrl_abmc_config_one_amd() to
monitor.c.
Added the code to reset the arch state in resctrl_arch_assign_cntr(). Also removed resctrl_arch_reset_rmid() inside IPI as the counters are reset from the callers.
Re-wrote commit message.

v10: Added call resctrl_arch_reset_rmid() to reset the RMID in the domain
inside IPI call.
SMP and non-SMP call support is not required in resctrl_arch_config_cntr with new domain specific assign approach/data structure. Commit message update.

v9: Removed the code to reset the architectural state. It will done
in another patch.

v8: Rename resctrl_arch_assign_cntr to resctrl_arch_config_cntr.

v7: Separated arch and fs functions. This patch only has arch implementation.
Added struct rdt_resource to the interface resctrl_arch_assign_cntr. Rename rdtgroup_abmc_cfg() to resctrl_abmc_config_one_amd().

v6: Removed mbm_cntr_alloc() from this patch to keep fs and arch code
separate.
Added code to update the counter assignment at domain level.

v5: Few name changes to match cntr_id.
Changed the function names to
rdtgroup_assign_cntr
resctr_arch_assign_cntr
More comments on commit log.
Added function summary.

v4: Commit message update.
User bitmap APIs where applicable. Changed the interfaces considering MPAM(arm). Added domain specific assignment.

v3: Removed the static from the prototype of rdtgroup_assign_abmc.
The function is not called directly from user anymore. These changes are related to global assignment interface.

v2: Minor text changes in commit message.

---
 arch/x86/kernel/cpu/resctrl/monitor.c | 36 +++++++++++++++++++++++++++
 include/linux/resctrl.h               | 19 ++++++++++++++
 2 files changed, 55 insertions(+)

index cce35a0ad455..ed295a6c5e66 100644
@@ -444,3 +444,39 @@ bool resctrl_arch_mbm_cntr_assign_enabled(struct rdt_resource *r)
 {
 	return resctrl_to_arch_res(r)->mbm_cntr_assign_enabled;
 }
+
+static void resctrl_abmc_config_one_amd(void *info)
+{
+	union l3_qos_abmc_cfg *abmc_cfg = info;
+
+	wrmsrl(MSR_IA32_L3_QOS_ABMC_CFG, abmc_cfg->full);
+}
+
+/*
+ * Send an IPI to the domain to assign the counter to RMID, event pair.
+ */
+void resctrl_arch_config_cntr(struct rdt_resource *r, struct rdt_mon_domain *d,
+			      enum resctrl_event_id evtid, u32 rmid, u32 closid,
+			      u32 cntr_id, bool assign)
+{
+	struct rdt_hw_mon_domain *hw_dom = resctrl_to_arch_mon_dom(d);
+	union l3_qos_abmc_cfg abmc_cfg = { 0 };
+	struct arch_mbm_state *am;
+
+	abmc_cfg.split.cfg_en = 1;
+	abmc_cfg.split.cntr_en = assign ? 1 : 0;
+	abmc_cfg.split.cntr_id = cntr_id;
+	abmc_cfg.split.bw_src = rmid;
+	if (assign)
+		abmc_cfg.split.bw_type = resctrl_get_mon_evt_cfg(evtid);
+
+	smp_call_function_any(&d->hdr.cpu_mask, resctrl_abmc_config_one_amd, &abmc_cfg, 1);
+
+	/*
+	 * The hardware counter is reset (because cfg_en == 1) so there is no
+	 * need to record initial non-zero counts.
+	 */
+	am = get_arch_mbm_state(hw_dom, rmid, evtid);
+	if (am)
+		memset(am, 0, sizeof(*am));
+}

index 87daa4ca312d..50e38445183a 100644
@@ -594,6 +594,25 @@ void resctrl_arch_reset_rmid_all(struct rdt_resource *r, struct rdt_mon_domain *
  */
 void resctrl_arch_reset_all_ctrls(struct rdt_resource *r);
 
+/**
+ * resctrl_arch_config_cntr() - Configure the counter with its new RMID
+ *				and event details.
+ * @r:			Resource structure.
+ * @d:			The domain in which counter with ID @cntr_id should be configured.
+ * @evtid:		Monitoring event type (e.g., QOS_L3_MBM_TOTAL_EVENT_ID
+ *			or QOS_L3_MBM_LOCAL_EVENT_ID).
+ * @rmid:		RMID.
+ * @closid:		CLOSID.
+ * @cntr_id:		Counter ID to configure.
+ * @assign:		True to assign the counter or update an existing assignment,
+ *			false to unassign the counter.
+ *
+ * This can be called from any CPU.
+ */
+void resctrl_arch_config_cntr(struct rdt_resource *r, struct rdt_mon_domain *d,
+			      enum resctrl_event_id evtid, u32 rmid, u32 closid,
+			      u32 cntr_id, bool assign);
+
 extern unsigned int resctrl_rmid_realloc_threshold;
 extern unsigned int resctrl_rmid_realloc_limit;
 

2.34.1

Hi Babu,

Reinette

When supported, "mbm_event" counter assignment mode offers "num_mbm_cntrs" number of counters that can be assigned to RMID, event pairs and monitor bandwidth usage as long as it is assigned.

Add the functionality to allocate and assign a counter to an RMID, event pair in the domain.

If all the counters are in use, kernel will log the error message "Failed to allocate counter for <event> in domain <id>" in /sys/fs/resctrl/info/last_cmd_status when a new assignment is requested. Exit on the first failure when assigning counters across all the domains.

---
v16: Function renames:
resctrl_config_cntr() -> rdtgroup_assign_cntr() rdtgroup_alloc_config_cntr() -> rdtgroup_alloc_assign_cntr()
Passed struct mevt to rdtgroup_alloc_assign_cntr so it can print event name on failure. Minor code comment update.

v15: Updated the changelog.

     Added the check !r->mon.mbm_cntr_assignable in mbm_cntr_get() to return error.
     Removed the check to verify evt_cfg in the domain as it is not required anymore.
     https://lore.kernel.org/lkml/[email protected]/
     Return success if the counter is already assigned.
     Rename resctrl_assign_cntr_event() -> rdtgroup_assign_cntr_event().
     Removed the parameter struct rdt_resource. It can be obtained from mevt->rid.

v14: Updated the changelog little bit.
Updated the code documentation for mbm_cntr_alloc() and mbm_cntr_get(). Passed struct mon_evt to resctrl_assign_cntr_event() that way to avoid back and forth calls to get event details.
Updated the code documentation about the failure when counters are exhasted. Changed subject line to fs/resctrl.

v13: Updated changelog.
Changed resctrl_arch_config_cntr() to return void instead of int. Just passing evtid is to resctrl_alloc_config_cntr() and resctrl_assign_cntr_event(). Event configuration value can be easily obtained from mon_evt list.
Introduced new function mbm_get_mon_event() to get event configuration value. Added prototype descriptions to mbm_cntr_get() and mbm_cntr_alloc(). Resolved conflicts caused by the recent FS/ARCH code restructure. The files monitor.c/rdtgroup.c have been split between FS and ARCH directories.

v12: Fixed typo in the subjest line.
Replaced several counters with "num_mbm_cntrs" counters.
Changed the check in resctrl_alloc_config_cntr() to reduce the indentation. Fixed the handling error on first failure.
Added domain id and event id on failure.
Fixed the return error override.
Added new parameter event configuration (evt_cfg) to get the event configuration from user space.

v11: Patch changed again quite a bit.
Moved the functions to monitor.c.
Renamed rdtgroup_assign_cntr_event() to resctrl_assign_cntr_event(). Refactored the resctrl_assign_cntr_event().
Added functionality to exit on the first error during assignment. Simplified mbm_cntr_free().
Removed the function mbm_cntr_assigned(). Will be using mbm_cntr_get() to figure out if the counter is assigned or not.
Updated commit message and code comments.

v10: Patch changed completely.
Counters are managed at the domain based on the discussion.
https://lore.kernel.org/lkml/CALPaoCj+zWq1vkHVbXYP0znJbe6Ke3PXPWjtri5AFgD9cQDCUg@mail.gmail.com/
Reset non-architectural MBM state.
Commit message update.

v9: Introduced new function resctrl_config_cntr to assign the counter, update
the bitmap and reset the architectural state.
Taken care of error handling(freeing the counter) when assignment fails. Moved mbm_cntr_assigned_to_domain here as it used in this patch. Minor text changes.

v8: Renamed rdtgroup_assign_cntr() to rdtgroup_assign_cntr_event().
Added the code to return the error if rdtgroup_assign_cntr_event fails. Moved definition of MBM_EVENT_ARRAY_INDEX to resctrl/internal.h. Updated typo in the comments.

v7: New patch. Moved all the FS code here.
Merged rdtgroup_assign_cntr and rdtgroup_alloc_cntr. Adde new #define MBM_EVENT_ARRAY_INDEX.

---
 fs/resctrl/internal.h |   3 +
 fs/resctrl/monitor.c  | 130 ++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 133 insertions(+)

index db3a0f12ad77..419423bdabdc 100644
@@ -387,6 +387,9 @@ bool closid_allocated(unsigned int closid);
 
 int resctrl_find_cleanest_closid(void);
 
+int rdtgroup_assign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdtgrp,
+			       struct mon_evt *mevt);
+
 #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
 int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);
 

2.34.1

Hi Babu,

I think dropping "kernel will" will help the text to be imperative.

"when a new assignment is requested" can be dropped. Or alternatively:
Log the error message "Failed to allocate counter for <event> in domain <id>" in /sys/fs/resctrl/info/last_cmd_status if all the counters are in use.

...

...

Hi Reinette,

Sure. will do.

Yes. Brought rdtgroup_assign_cntrs() in this patch for completeness and moved everything into monitor.c.

Sure.

Thanks
Babu Moger