enable x2APIC without interrupt remapping under KVM
PATCH v5 1/1 enable x2APIC without interrupt remapping under KVM
KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better virtualizable and provides better performance than mmio xAPIC interface:
- msr exits are faster than mmio (no page table walk, emulation)
- no need to read back ICR to look at the busy bit
- one 64 bit ICR write instead of two 32 bit writes
- shared code with the Hyper-V paravirt interface
Included patch changes x2APIC enabling logic to enable it even if IR initialization failed, but kernel runs under KVM and no apic id is greater than 255 (if there is one spec requires BIOS to move to x2apic mode before starting an OS).
---
This version does not rely on x2apic_preenabled to determine max APIC id since this logic will break after kexec. Use max_physical_apicid instead. Also allow to override apic ops after call to enable_IR_x2apic() since we may decide to use physical mode instead of cluster.
arch/x86/kernel/apic/apic.c +47 -35
@@ -49,6 +49,7 @@#include <asm/mtrr.h> #include <asm/smp.h> #include <asm/mce.h> +#include <asm/kvm_para.h> unsigned int num_processors;
@@ -1363,52 +1364,74 @@ void enable_x2apic(void) }#endif /* CONFIG_X86_X2APIC */ -void __init enable_IR_x2apic (void ) +int __init enable_IR (void ) {#ifdef CONFIG_INTR_REMAP int ret; -unsigned long flags; -struct IO_APIC_route_entry **ioapic_entries =NULL ; ret =dmar_table_init ();if (ret) {pr_debug ("dmar_table_init() failed with %d:\n" , ret); - goto ir_failed; +return 0 ; }if (!intr_remapping_supported ()) {pr_debug ("intr-remapping not supported\n" ); - goto ir_failed; +return 0 ; } -if (!x2apic_preenabled && skip_ioapic_setup) {pr_info ("Skipped enabling intr-remap because of skipping " "io-apic setup\n" ); -return ; +return 0 ; } +if (enable_intr_remapping (x2apic_supported ())) +return 0 ; + +pr_info ("Enabled Interrupt-remapping\n" ); + +return 1 ; + +#endif +return 0 ; +} + +void __init enable_IR_x2apic (void ) +{ +unsigned long flags; +struct IO_APIC_route_entry **ioapic_entries =NULL ; +int ret, x2apic_enabled =0 ; + ioapic_entries =alloc_ioapic_entries ();if (!ioapic_entries) { -pr_info ("Allocate ioapic_entries failed: %d\n" , ret); - goto end; +pr_info ("Allocate ioapic_entries failed\n" ); + goto out; } ret =save_IO_APIC_setup (ioapic_entries);if (ret) {pr_info ("Saving IO-APIC state failed: %d\n" , ret); - goto end; + goto out; }local_irq_save (flags); -mask_IO_APIC_setup (ioapic_entries);mask_8259A (); +mask_IO_APIC_setup (ioapic_entries); - ret =enable_intr_remapping (x2apic_supported ()); -if (ret) - goto end_restore; + ret =enable_IR (); +if (!ret) { +/* IR is required if x2apic is enabled by BIOS even +* when running in kvm since this indicates present +* of APIC ID > 255 */ +if (max_physical_apicid >255 || !kvm_para_available ()) + goto nox2apic; +/* without IR all CPUs can be addressed by IOAPIC/MSI +* only in physical mode */ + x2apic_phys =1 ; + } -pr_info ("Enabled Interrupt-remapping\n" ); + x2apic_enabled =1 ;if (x2apic_supported () && !x2apic_mode) { x2apic_mode =1 ;
@@ -1416,41 +1439,30 @@ void __init enable_IR_x2apic(void)pr_info ("Enabled x2apic\n" ); } -end_restore: -if (ret) -/* -* IR enabling failed -*/ +nox2apic: +if (!ret)/* IR enabling failed */ restore_IO_APIC_setup (ioapic_entries); -unmask_8259A ();local_irq_restore (flags); -end: +out:if (ioapic_entries)free_ioapic_entries (ioapic_entries); -if (!ret) +if (x2apic_enabled)return ; -ir_failed: -if (x2apic_preenabled) +if (x2apic_preenabled) { +#ifdef CONFIG_INTR_REMAP panic ("x2apic enabled by bios. But IR enabling failed" ); -else if (cpu_has_x2apic) -pr_info ("Not enabling x2apic,Intr-remapping\n" );#else -if (!cpu_has_x2apic) -return ; - -if (x2apic_preenabled)panic ("x2apic enabled prior OS handover," -" enable CONFIG_X86_X2APIC, CONFIG_INTR_REMAP" ); +" enable CONFIG_X86_X2APIC, CONFIG_INTR_REMAP" );#endif - -return ; + }else if (cpu_has_x2apic) +pr_info ("Not enabling x2apic,Intr-remapping\n" ); } -#ifdef CONFIG_X86_64 /* * Detect and enable local APICs on non-SMP boards.
arch/x86/kernel/apic/probe_64.c +3 -3
@@ -50,11 +50,11 @@ static struct apic *apic_probe[] __initdata = {void __init default_setup_apic_routing (void ) {#ifdef CONFIG_X86_X2APIC -if (x2apic_mode && (apic != &apic_x2apic_phys && +if (x2apic_mode #ifdef CONFIG_X86_UV - apic != &apic_x2apic_uv_x && + && apic != &apic_x2apic_uv_x #endif - apic != &apic_x2apic_cluster)) { + ) {if (x2apic_phys) apic = &apic_x2apic_phys;else
--
Gleb.
Quoted 10 lines · Gleb Natapov
KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better virtualizable and provides better performance than mmio xAPIC interface:
- msr exits are faster than mmio (no page table walk, emulation)
- no need to read back ICR to look at the busy bit
- one 64 bit ICR write instead of two 32 bit writes
- shared code with the Hyper-V paravirt interface
Quoted 6 lines
Included patch changes x2APIC enabling logic to enable it even if IR initialization failed, but kernel runs under KVM and no apic id is greater than 255 (if there is one spec requires BIOS to move to x2apic mode before starting an OS).
Signed-off-by Gleb Natapov <[email protected]>
Quoted 11 lines · Suresh Siddha
Quoted 10 lines · Gleb Natapov
KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better virtualizable and provides better performance than mmio xAPIC interface:
- msr exits are faster than mmio (no page table walk, emulation)
- no need to read back ICR to look at the busy bit
- one 64 bit ICR write instead of two 32 bit writes
- shared code with the Hyper-V paravirt interface
Quoted 8 lines
Quoted 6 lines
Included patch changes x2APIC enabling logic to enable it even if IR initialization failed, but kernel runs under KVM and no apic id is greater than 255 (if there is one spec requires BIOS to move to x2apic mode before starting an OS).
Signed-off-by Gleb Natapov <[email protected]>Acked-by Suresh Siddha <[email protected]>
Now, since this affects core x86 APIC code non-trivially so should submitted to and go via the x86 tree. (Can prepare a special branch with just this change if KVM tree wants/needs to pull it before v2.6.32.)
Ingo
Quoted 18 lines · Ingo Molnar
Quoted 16 lines · Suresh Siddha
Quoted 15 lines · Gleb Natapov
KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better virtualizable and provides better performance than mmio xAPIC interface:
- msr exits are faster than mmio (no page table walk, emulation)
- no need to read back ICR to look at the busy bit
- one 64 bit ICR write instead of two 32 bit writes
- shared code with the Hyper-V paravirt interfaceIncluded patch changes x2APIC enabling logic to enable it even if IR initialization failed, but kernel runs under KVM and no apic id is greater than 255 (if there is one spec requires BIOS to move to x2apic mode before starting an OS).
Quoted 8 lines
Quoted 3 lines
Quoted 1 line
Signed-off-by Gleb Natapov <[email protected]>Acked-by Suresh Siddha <[email protected]>Now, since this affects core x86 APIC code non-trivially so should submitted to and go via the x86 tree. (Can prepare a special branch with just this change if KVM tree wants/needs to pull it before v2.6.32.)
Please don't separate the x2apic code from the dmar code for this reason.
Supporting hotplug cpus with ioapics is torture.
Eric
Quoted 29 lines · Eric W. Biederman
Quoted 18 lines · Ingo Molnar
Quoted 16 lines · Suresh Siddha
Quoted 15 lines · Gleb Natapov
KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better virtualizable and provides better performance than mmio xAPIC interface:
- msr exits are faster than mmio (no page table walk, emulation)
- no need to read back ICR to look at the busy bit
- one 64 bit ICR write instead of two 32 bit writes
- shared code with the Hyper-V paravirt interfaceIncluded patch changes x2APIC enabling logic to enable it even if IR initialization failed, but kernel runs under KVM and no apic id is greater than 255 (if there is one spec requires BIOS to move to x2apic mode before starting an OS).
Quoted 8 lines
Quoted 3 lines
Quoted 1 line
Signed-off-by Gleb Natapov <[email protected]>Acked-by Suresh Siddha <[email protected]>Now, since this affects core x86 APIC code non-trivially so should submitted to and go via the x86 tree. (Can prepare a special branch with just this change if KVM tree wants/needs to pull it before v2.6.32.)
Quoted 5 lines
Please don't separate the x2apic code from the dmar code for this reason.
Supporting hotplug cpus with ioapics is torture.
What is the connection between this patch and cpu hotplug?
--
Gleb.
Quoted 30 lines · Gleb Natapov
Quoted 29 lines · Eric W. Biederman
Quoted 26 lines · Ingo Molnar
Quoted 11 lines · Suresh Siddha
Quoted 10 lines · Gleb Natapov
KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better virtualizable and provides better performance than mmio xAPIC interface:
- msr exits are faster than mmio (no page table walk, emulation)
- no need to read back ICR to look at the busy bit
- one 64 bit ICR write instead of two 32 bit writes
- shared code with the Hyper-V paravirt interfaceQuoted 8 lines
Quoted 6 lines
Included patch changes x2APIC enabling logic to enable it even if IR initialization failed, but kernel runs under KVM and no apic id is greater than 255 (if there is one spec requires BIOS to move to x2apic mode before starting an OS).
Signed-off-by Gleb Natapov <[email protected]>Acked-by Suresh Siddha <[email protected]>Now, since this affects core x86 APIC code non-trivially so should submitted to and go via the x86 tree. (Can prepare a special branch with just this change if KVM tree wants/needs to pull it before v2.6.32.)
Quoted 6 lines
Quoted 5 lines
Please don't separate the x2apic code from the dmar code for this reason.
Supporting hotplug cpus with ioapics is torture.
What is the connection between this patch and cpu hotplug?
When I asked if cpu hotplug was a supported and more or less common feature of kvm I was told it was.
Good cpu hotplug today means supporting interrupt remapping. (The code you are disabling for kvm).
Therefore I don't see the point of supporting one without the other. Especially if we don't have a case where on real hardware we need to split the support.
Eric
Quoted 35 lines · Eric W. Biederman
Quoted 33 lines · Gleb Natapov
Quoted 32 lines · Eric W. Biederman
Quoted 18 lines · Ingo Molnar
Quoted 16 lines · Suresh Siddha
Quoted 15 lines · Gleb Natapov
KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better virtualizable and provides better performance than mmio xAPIC interface:
- msr exits are faster than mmio (no page table walk, emulation)
- no need to read back ICR to look at the busy bit
- one 64 bit ICR write instead of two 32 bit writes
- shared code with the Hyper-V paravirt interfaceIncluded patch changes x2APIC enabling logic to enable it even if IR initialization failed, but kernel runs under KVM and no apic id is greater than 255 (if there is one spec requires BIOS to move to x2apic mode before starting an OS).
Quoted 8 lines
Quoted 3 lines
Quoted 1 line
Signed-off-by Gleb Natapov <[email protected]>Acked-by Suresh Siddha <[email protected]>Now, since this affects core x86 APIC code non-trivially so should submitted to and go via the x86 tree. (Can prepare a special branch with just this change if KVM tree wants/needs to pull it before v2.6.32.)
Please don't separate the x2apic code from the dmar code for this reason.
Quoted 7 lines
Quoted 3 lines
Quoted 2 lines
Supporting hotplug cpus with ioapics is torture.
What is the connection between this patch and cpu hotplug?
When I asked if cpu hotplug was a supported and more or less common feature of kvm I was told it was.
It is supported in a sense that cpus can be created dynamically and DSDT has objects to inform OS that a cpu state changed. I don't know how common it is. I surely don't use it daily. But 99% of the real work is done by a guest.
Quoted 3 lines
Good cpu hotplug today means supporting interrupt remapping. (The code you are disabling for kvm).
From you previous mails I understand that the problem is no with cpu
hotplug, but with cpu offlining and this is the guest feature that cannot be controlled by KVM in any way. If you think that Linux should not support cpu offlining with ioapics fine, send a patch to disable it and cpu hot-unplug will not be supported by KVM with Linux guests, but note that KVM ioapic has no problems that you've mentioned and HW makers that provide x86 hardware may be using more sophisticated ioapics that you've tested (I don't know never saw such hardware).
Quoted 2 lines
Therefore I don't see the point of supporting one without the other.
x2apic provide us with other benefits as commit message explains, and doesn't add any problems that we don't have now already.
Quoted 3 lines
Especially if we don't have a case where on real hardware we need to split the support.
--
Gleb.
Quoted 3 lines · Gleb Natapov
Quoted 1 line
Therefore I don't see the point of supporting one without the other.
x2apic provide us with other benefits as commit message explains, and doesn't add any problems that we don't have now already.
If this code has a legitimate place on real hardware I am all for it.
If this is just a hack to make virtualization faster I don't like the extra code paths in the middle core architecture code. That will be a support burden for the foreseeable future. More code to test etc.
Quickly skimming the patch it just appears to stir a mess. Plus it adds weird paravirtualization checks, ???
If we are going to have a special code path for virtual hardware can we do it right and have something nice to use that makes life simpler? For what we want to do with ioapics they suck and are really not suitable. The only thing that recommends them is that they are standard. But you are deviating from the standard so what is the point.
Eric
Quoted 11 lines · Eric W. Biederman
Quoted 5 lines · Gleb Natapov
Quoted 2 lines
Therefore I don't see the point of supporting one without the other.
x2apic provide us with other benefits as commit message explains, and doesn't add any problems that we don't have now already.
If this code has a legitimate place on real hardware I am all for it.
As I understood it, x2apic without interrupt remapping will work but is not a validated configuration. Interrupt remapping is only necessary if you have > 255 hardware threads + ioapics. The features are logically separate and are only tied together by the vendor's validation practices.
Quoted 5 lines
If this is just a hack to make virtualization faster I don't like the extra code paths in the middle core architecture code. That will be a support burden for the foreseeable future. More code to test etc.
There aren't any extra code paths. The patch separates a long function into two smaller ones that each do one thing, and adds a check for kvm.
Maybe it should be split into two to makes that clear. The first patch simplifies the code, the second adds a kvm check.
Quoted 3 lines
Quickly skimming the patch it just appears to stir a mess. Plus it adds weird paravirtualization checks, ???
It adds exactly one "weird paravirtualization check ???", then one described in the patch description.
Quoted 3 lines
If we are going to have a special code path for virtual hardware can we do it right and have something nice to use that makes life simpler?
You mean, instead of adding one check in an initialization code path, create a new irqchip, a way of describing the topology to the guest, support code in kvm (as host)?
Quoted 5 lines
For what we want to do with ioapics they suck and are really not suitable. The only thing that recommends them is that they are standard. But you are deviating from the standard so what is the point.
All of the code continues to work.
Signature · 1 line
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
Quoted 5 lines · Ingo Molnar
Now, since this affects core x86 APIC code non-trivially so should submitted to and go via the x86 tree. (Can prepare a special branch with just this change if KVM tree wants/needs to pull it before v2.6.32.)
The kvm tree won't depend on this change. I'm happy with it going into 2.6.32 via tip.git.
Signature · 1 line
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
PATCH 1/1 enable x2APIC without interrupt remapping under KVM
In reply to Ingo MolnarKVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better virtualizable and provides better performance than mmio xAPIC interface:
- msr exits are faster than mmio (no page table walk, emulation)
- no need to read back ICR to look at the busy bit
- one 64 bit ICR write instead of two 32 bit writes
- shared code with the Hyper-V paravirt interface
Included patch changes x2APIC enabling logic to enable it even if IR initialization failed, but kernel runs under KVM and no apic id is greater than 255 (if there is one spec requires BIOS to move to x2apic mode before starting an OS).
---
This is the same as v5 only rebased on x86 tree (a74d2cea).
arch/x86/kernel/apic/apic.c +47 -35
@@ -49,6 +49,7 @@#include <asm/mtrr.h> #include <asm/smp.h> #include <asm/mce.h> +#include <asm/kvm_para.h> unsigned int num_processors;
@@ -1361,52 +1362,74 @@ void enable_x2apic(void) }#endif /* CONFIG_X86_X2APIC */ -void __init enable_IR_x2apic (void ) +int __init enable_IR (void ) {#ifdef CONFIG_INTR_REMAP int ret; -unsigned long flags; -struct IO_APIC_route_entry **ioapic_entries =NULL ; ret =dmar_table_init ();if (ret) {pr_debug ("dmar_table_init() failed with %d:\n" , ret); - goto ir_failed; +return 0 ; }if (!intr_remapping_supported ()) {pr_debug ("intr-remapping not supported\n" ); - goto ir_failed; +return 0 ; } -if (!x2apic_preenabled && skip_ioapic_setup) {pr_info ("Skipped enabling intr-remap because of skipping " "io-apic setup\n" ); -return ; +return 0 ; } +if (enable_intr_remapping (x2apic_supported ())) +return 0 ; + +pr_info ("Enabled Interrupt-remapping\n" ); + +return 1 ; + +#endif +return 0 ; +} + +void __init enable_IR_x2apic (void ) +{ +unsigned long flags; +struct IO_APIC_route_entry **ioapic_entries =NULL ; +int ret, x2apic_enabled =0 ; + ioapic_entries =alloc_ioapic_entries ();if (!ioapic_entries) { -pr_info ("Allocate ioapic_entries failed: %d\n" , ret); - goto end; +pr_info ("Allocate ioapic_entries failed\n" ); + goto out; } ret =save_IO_APIC_setup (ioapic_entries);if (ret) {pr_info ("Saving IO-APIC state failed: %d\n" , ret); - goto end; + goto out; }local_irq_save (flags); -mask_IO_APIC_setup (ioapic_entries);mask_8259A (); +mask_IO_APIC_setup (ioapic_entries); - ret =enable_intr_remapping (x2apic_supported ()); -if (ret) - goto end_restore; + ret =enable_IR (); +if (!ret) { +/* IR is required if x2apic is enabled by BIOS even +* when running in kvm since this indicates present +* of APIC ID > 255 */ +if (max_physical_apicid >255 || !kvm_para_available ()) + goto nox2apic; +/* without IR all CPUs can be addressed by IOAPIC/MSI +* only in physical mode */ + x2apic_phys =1 ; + } -pr_info ("Enabled Interrupt-remapping\n" ); + x2apic_enabled =1 ;if (x2apic_supported () && !x2apic_mode) { x2apic_mode =1 ;
@@ -1414,41 +1437,30 @@ void __init enable_IR_x2apic(void)pr_info ("Enabled x2apic\n" ); } -end_restore: -if (ret) -/* -* IR enabling failed -*/ +nox2apic: +if (!ret)/* IR enabling failed */ restore_IO_APIC_setup (ioapic_entries); -unmask_8259A ();local_irq_restore (flags); -end: +out:if (ioapic_entries)free_ioapic_entries (ioapic_entries); -if (!ret) +if (x2apic_enabled)return ; -ir_failed: -if (x2apic_preenabled) +if (x2apic_preenabled) { +#ifdef CONFIG_INTR_REMAP panic ("x2apic enabled by bios. But IR enabling failed" ); -else if (cpu_has_x2apic) -pr_info ("Not enabling x2apic,Intr-remapping\n" );#else -if (!cpu_has_x2apic) -return ; - -if (x2apic_preenabled)panic ("x2apic enabled prior OS handover," -" enable CONFIG_X86_X2APIC, CONFIG_INTR_REMAP" ); +" enable CONFIG_X86_X2APIC, CONFIG_INTR_REMAP" );#endif - -return ; + }else if (cpu_has_x2apic) +pr_info ("Not enabling x2apic,Intr-remapping\n" ); } -#ifdef CONFIG_X86_64 /* * Detect and enable local APICs on non-SMP boards.
arch/x86/kernel/apic/probe_64.c +3 -3
@@ -50,11 +50,11 @@ static struct apic *apic_probe[] __initdata = {void __init default_setup_apic_routing (void ) {#ifdef CONFIG_X86_X2APIC -if (x2apic_mode && (apic != &apic_x2apic_phys && +if (x2apic_mode #ifdef CONFIG_X86_UV - apic != &apic_x2apic_uv_x && + && apic != &apic_x2apic_uv_x #endif - apic != &apic_x2apic_cluster)) { + ) {if (x2apic_phys) apic = &apic_x2apic_phys;else
--
Gleb.
Quoted 15 lines · Gleb Natapov
KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better virtualizable and provides better performance than mmio xAPIC interface:
- msr exits are faster than mmio (no page table walk, emulation)
- no need to read back ICR to look at the busy bit
- one 64 bit ICR write instead of two 32 bit writes
- shared code with the Hyper-V paravirt interfaceIncluded patch changes x2APIC enabling logic to enable it even if IR initialization failed, but kernel runs under KVM and no apic id is greater than 255 (if there is one spec requires BIOS to move to x2apic mode before starting an OS).
Quoted 5 lines
Signed-off-by Gleb Natapov <[email protected]>Acked-by Suresh Siddha <[email protected]>---
This is the same as v5 only rebased on x86 tree (
a74d2cea).
Looks good.
Small detail: please run the patch through scripts/checkpatch.pl and fix the complaints it has - all 3 details it points out seem like valid complaints to me (at a quick glance) that should be fixed.
Thanks,
Ingo
PATCH 1/1 enable x2APIC without interrupt remapping under KVM
KVM would like to provide x2APIC interface to a guest without emulating interrupt remapping device. The reason KVM prefers guest to use x2APIC is that x2APIC interface is better virtualizable and provides better performance than mmio xAPIC interface:
- msr exits are faster than mmio (no page table walk, emulation)
- no need to read back ICR to look at the busy bit
- one 64 bit ICR write instead of two 32 bit writes
- shared code with the Hyper-V paravirt interface
Included patch changes x2APIC enabling logic to enable it even if IR initialization failed, but kernel runs under KVM and no apic id is greater than 255 (if there is one spec requires BIOS to move to x2apic mode before starting an OS).
---
This is based on x86 tree commit 5b9eea3e7 with checkpatch complains fixed.
arch/x86/kernel/apic/apic.c +47 -35
@@ -49,6 +49,7 @@#include <asm/mtrr.h> #include <asm/smp.h> #include <asm/mce.h> +#include <asm/kvm_para.h> unsigned int num_processors;
@@ -1361,52 +1362,74 @@ void enable_x2apic(void) }#endif /* CONFIG_X86_X2APIC */ -void __init enable_IR_x2apic (void ) +int __init enable_IR (void ) {#ifdef CONFIG_INTR_REMAP int ret; -unsigned long flags; -struct IO_APIC_route_entry **ioapic_entries =NULL ; ret =dmar_table_init ();if (ret) {pr_debug ("dmar_table_init() failed with %d:\n" , ret); - goto ir_failed; +return 0 ; }if (!intr_remapping_supported ()) {pr_debug ("intr-remapping not supported\n" ); - goto ir_failed; +return 0 ; } -if (!x2apic_preenabled && skip_ioapic_setup) {pr_info ("Skipped enabling intr-remap because of skipping " "io-apic setup\n" ); -return ; +return 0 ; } +if (enable_intr_remapping (x2apic_supported ())) +return 0 ; + +pr_info ("Enabled Interrupt-remapping\n" ); + +return 1 ; + +#endif +return 0 ; +} + +void __init enable_IR_x2apic (void ) +{ +unsigned long flags; +struct IO_APIC_route_entry **ioapic_entries =NULL ; +int ret, x2apic_enabled =0 ; + ioapic_entries =alloc_ioapic_entries ();if (!ioapic_entries) { -pr_info ("Allocate ioapic_entries failed: %d\n" , ret); - goto end; +pr_info ("Allocate ioapic_entries failed\n" ); + goto out; } ret =save_IO_APIC_setup (ioapic_entries);if (ret) {pr_info ("Saving IO-APIC state failed: %d\n" , ret); - goto end; + goto out; }local_irq_save (flags); -mask_IO_APIC_setup (ioapic_entries);mask_8259A (); +mask_IO_APIC_setup (ioapic_entries); - ret =enable_intr_remapping (x2apic_supported ()); -if (ret) - goto end_restore; + ret =enable_IR (); +if (!ret) { +/* IR is required if x2apic is enabled by BIOS even +* when running in kvm since this indicates present +* of APIC ID > 255 */ +if (max_physical_apicid >255 || !kvm_para_available ()) + goto nox2apic; +/* without IR all CPUs can be addressed by IOAPIC/MSI +* only in physical mode */ + x2apic_phys =1 ; + } -pr_info ("Enabled Interrupt-remapping\n" ); + x2apic_enabled =1 ;if (x2apic_supported () && !x2apic_mode) { x2apic_mode =1 ;
@@ -1414,41 +1437,30 @@ void __init enable_IR_x2apic(void)pr_info ("Enabled x2apic\n" ); } -end_restore: -if (ret) -/* -* IR enabling failed -*/ +nox2apic: +if (!ret)/* IR enabling failed */ restore_IO_APIC_setup (ioapic_entries); -unmask_8259A ();local_irq_restore (flags); -end: +out:if (ioapic_entries)free_ioapic_entries (ioapic_entries); -if (!ret) +if (x2apic_enabled)return ; -ir_failed: -if (x2apic_preenabled) +if (x2apic_preenabled) { +#ifdef CONFIG_INTR_REMAP panic ("x2apic enabled by bios. But IR enabling failed" ); -else if (cpu_has_x2apic) -pr_info ("Not enabling x2apic,Intr-remapping\n" );#else -if (!cpu_has_x2apic) -return ; - -if (x2apic_preenabled)panic ("x2apic enabled prior OS handover," -" enable CONFIG_X86_X2APIC, CONFIG_INTR_REMAP" ); +" enable CONFIG_X86_X2APIC, CONFIG_INTR_REMAP" );#endif - -return ; + }else if (cpu_has_x2apic) +pr_info ("Not enabling x2apic,Intr-remapping\n" ); } -#ifdef CONFIG_X86_64 /* * Detect and enable local APICs on non-SMP boards.
arch/x86/kernel/apic/probe_64.c +3 -3
@@ -50,11 +50,11 @@ static struct apic *apic_probe[] __initdata = {void __init default_setup_apic_routing (void ) {#ifdef CONFIG_X86_X2APIC -if (x2apic_mode && (apic != &apic_x2apic_phys && +if (x2apic_mode #ifdef CONFIG_X86_UV - apic != &apic_x2apic_uv_x && + && apic != &apic_x2apic_uv_x #endif - apic != &apic_x2apic_cluster)) { + ) {if (x2apic_phys) apic = &apic_x2apic_phys;else
--
Gleb.
i've only got some small stylistic gripes:
arch/x86/kernel/apic/apic.c void enable_x2apic(void) · line 1407
Quoted 12 lines
arch/x86/kernel/apic/apic.c +8
-2+void __init enable_IR_x2apic (void ) +{ +unsigned long flags; +struct IO_APIC_route_entry **ioapic_entries =NULL ; +int ret, x2apic_enabled =0 ; + ioapic_entries =alloc_ioapic_entries ();if (!ioapic_entries) { -pr_info ("Allocate ioapic_entries failed: %d\n" , ret); - goto end; +pr_info ("Allocate ioapic_entries failed\n" ); + goto out;
That's probably a fatal condition so perhaps a WARN() or pr_err() would be more appropriate.
arch/x86/kernel/apic/apic.c void enable_x2apic(void) · line 1424
Quoted 5 lines
arch/x86/kernel/apic/apic.c +5
-0+ ret =enable_IR (); +if (!ret) { +/* IR is required if x2apic is enabled by BIOS even +* when running in kvm since this indicates present +* of APIC ID > 255 */
please use the customary (multi-line) comment style:
/*
* Comment .....
* ...... goes here.
*/
specified in Documentation/CodingStyle.
arch/x86/kernel/apic/apic.c void enable_x2apic(void) · line 1428
Quoted 4 lines
arch/x86/kernel/apic/apic.c +4
-0+if (max_physical_apicid >255 || !kvm_para_available ()) + goto nox2apic; +/* without IR all CPUs can be addressed by IOAPIC/MSI +* only in physical mode */
ditto.
Quoted 39 lines
arch/x86/kernel/apic/apic.c +9
-12+ x2apic_phys =1 ; + } -pr_info ("Enabled Interrupt-remapping\n" ); + x2apic_enabled =1 ;if (x2apic_supported () && !x2apic_mode) { x2apic_mode =1 ;@@ -1414,41 +1437,30 @@ void __init enable_IR_x2apic(void)pr_info ("Enabled x2apic\n" ); } -end_restore: -if (ret) -/* -* IR enabling failed -*/ +nox2apic: +if (!ret)/* IR enabling failed */ restore_IO_APIC_setup (ioapic_entries); -unmask_8259A ();local_irq_restore (flags); -end: +out:if (ioapic_entries)free_ioapic_entries (ioapic_entries); -if (!ret) +if (x2apic_enabled)return ; -ir_failed: -if (x2apic_preenabled) +if (x2apic_preenabled) { +#ifdef CONFIG_INTR_REMAP panic ("x2apic enabled by bios. But IR enabling failed" ); -else if (cpu_has_x2apic)
arch/x86/kernel/apic/apic.c void __init enable_IR_x2apic(void) · line 1459
Quoted 10 lines
arch/x86/kernel/apic/apic.c +1
-6-pr_info ("Not enabling x2apic,Intr-remapping\n" );#else -if (!cpu_has_x2apic) -return ; - -if (x2apic_preenabled)panic ("x2apic enabled prior OS handover," -" enable CONFIG_X86_X2APIC, CONFIG_INTR_REMAP" ); +" enable CONFIG_X86_X2APIC, CONFIG_INTR_REMAP" );#endif
can this #ifdef be avoided?
arch/x86/kernel/apic/apic.c void __init enable_IR_x2apic(void) · line 1461
Quoted 4 lines
arch/x86/kernel/apic/apic.c +2
-2- -return ; + }else if (cpu_has_x2apic) +pr_info ("Not enabling x2apic,Intr-remapping\n" );
please put a space after commas.
Thanks,
Ingo