Patch "perf/x86/intel/cqm: Check cqm/mbm enabled state in event init" has been added to the 4.7-stable tree

This is a note to let you know that I've just added the patch titled

perf/x86/intel/cqm: Check cqm/mbm enabled state in event init

to the 4.7-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
perf-x86-intel-cqm-check-cqm-mbm-enabled-state-in-event-init.patch
and it can be found in the queue-4.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jiri Olsa <[email protected]>
Date: Mon, 5 Sep 2016 17:30:07 +0200
Subject: perf/x86/intel/cqm: Check cqm/mbm enabled state in event init

From: Jiri Olsa <[email protected]>

commit 79d102cbfd2e9d94257fcc7c82807ef1cdf80322 upstream.

Yanqiu Zhang reported kernel panic when using mbm event on system where CQM is detected but without mbm event support, like with perf:

  # perf stat -e 'intel_cqm/event=3/' -a

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
  IP: [<ffffffff8100d64c>] update_sample+0xbc/0xe0
  ...
   <IRQ>
   [<ffffffff8100d688>] __intel_mbm_event_init+0x18/0x20
   [<ffffffff81113d6b>] flush_smp_call_function_queue+0x7b/0x160
   [<ffffffff81114853>] generic_smp_call_function_single_interrupt+0x13/0x60
   [<ffffffff81052017>] smp_call_function_interrupt+0x27/0x40
   [<ffffffff816fb06c>] call_function_interrupt+0x8c/0xa0
  ...

The reason is that we currently allow to init mbm event even if mbm support is not detected. Adding checks for both cqm and mbm events and support into cqm's event_init.

---
 arch/x86/events/intel/cqm.c |    9 +++++++++
 1 file changed, 9 insertions(+)

@@ -458,6 +458,11 @@ static void __intel_cqm_event_count(void
 static void init_mbm_sample(u32 rmid, u32 evt_type);
 static void __intel_mbm_event_count(void *info);
 
+static bool is_cqm_event(int e)
+{
+	return (e == QOS_L3_OCCUP_EVENT_ID);
+}
+
 static bool is_mbm_event(int e)
 {
 	return (e >= QOS_MBM_TOTAL_EVENT_ID && e <= QOS_MBM_LOCAL_EVENT_ID);

@@ -1366,6 +1371,10 @@ static int intel_cqm_event_init(struct p
 	     (event->attr.config > QOS_MBM_LOCAL_EVENT_ID))
 		return -EINVAL;
 
+	if ((is_cqm_event(event->attr.config) && !cqm_enabled) ||
+	    (is_mbm_event(event->attr.config) && !mbm_enabled))
+		return -EINVAL;
+
 	/* unsupported modes and filters */
 	if (event->attr.exclude_user   ||
 	    event->attr.exclude_kernel ||

Patches currently in stable-queue which might be from [email protected] are

queue-4.7/perf-x86-intel-cqm-check-cqm-mbm-enabled-state-in-event-init.patch