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

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.

Fixes: 33c3cc7acfd9 ("perf/x86/mbm: Add Intel Memory B/W Monitoring enumeration and init")
Reported-by: Yanqiu Zhang <yanqzhan@redhat.com>
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Vikas Shivappa <vikas.shivappa@linux.intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/1473089407-21857-1-git-send-email-jolsa@kernel.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c
index 7b5fd811ef456a189f0271ad08f5044adb1b266f..4ff41ae514a3f146f82649a0283784cecc1990a4 100644 (file)
--- a/arch/x86/events/intel/cqm.c
+++ b/arch/x86/events/intel/cqm.c
@@ -458,6 +458,11 @@ static void __intel_cqm_event_count(void *info);
 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 perf_event *event)
             (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 ||