diff options
| author | Jim Mattson <jmattson@google.com> | 2021-04-21 17:18:34 -0700 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-04-22 14:36:01 +0200 |
| commit | 4b2f1e59229b9da319d358828cdfa4ddbc140769 (patch) | |
| tree | f53b83638635ae507f58751932438200e8898a2a | |
| parent | 9d480158ee86ad606d3a8baaf81e6b71acbfd7d5 (diff) | |
perf/x86/kvm: Fix Broadwell Xeon stepping in isolation_ucodes[]
The only stepping of Broadwell Xeon parts is stepping 1. Fix the
relevant isolation_ucodes[] entry, which previously enumerated
stepping 2.
Although the original commit was characterized as an optimization, it
is also a workaround for a correctness issue.
If a PMI arrives between kvm's call to perf_guest_get_msrs() and the
subsequent VM-entry, a stale value for the IA32_PEBS_ENABLE MSR may be
restored at the next VM-exit. This is because, unbeknownst to kvm, PMI
throttling may clear bits in the IA32_PEBS_ENABLE MSR. CPUs with "PEBS
isolation" don't suffer from this issue, because perf_guest_get_msrs()
doesn't report the IA32_PEBS_ENABLE value.
Fixes: 9b545c04abd4f ("perf/x86/kvm: Avoid unnecessary work in guest filtering")
Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Peter Shier <pshier@google.com>
Acked-by: Andi Kleen <ak@linux.intel.com>
Link: https://lkml.kernel.org/r/20210422001834.1748319-1-jmattson@google.com
| -rw-r--r-- | arch/x86/events/intel/core.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 37ce38403cb8..c57ec8e27907 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -4516,7 +4516,7 @@ static const struct x86_cpu_desc isolation_ucodes[] = { INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_D, 3, 0x07000009), INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_D, 4, 0x0f000009), INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_D, 5, 0x0e000002), - INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_X, 2, 0x0b000014), + INTEL_CPU_DESC(INTEL_FAM6_BROADWELL_X, 1, 0x0b000014), INTEL_CPU_DESC(INTEL_FAM6_SKYLAKE_X, 3, 0x00000021), INTEL_CPU_DESC(INTEL_FAM6_SKYLAKE_X, 4, 0x00000000), INTEL_CPU_DESC(INTEL_FAM6_SKYLAKE_X, 5, 0x00000000), |