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| author | Jim Mattson <jmattson@google.com> | 2021-04-21 17:18:34 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-04-28 13:41:49 +0200 |
| commit | 31216482abe66f2a7a5b776bf52ab4215e8ba130 (patch) | |
| tree | ef0e8dc06d291abbfb452432cc0d16dba029518f | |
| parent | d2c79105a90323a2a93484c85f9ac419ae9b183d (diff) | |
| download | linux-31216482abe66f2a7a5b776bf52ab4215e8ba130.tar.gz linux-31216482abe66f2a7a5b776bf52ab4215e8ba130.tar.bz2 linux-31216482abe66f2a7a5b776bf52ab4215e8ba130.zip | |
perf/x86/kvm: Fix Broadwell Xeon stepping in isolation_ucodes[]
[ Upstream commit 4b2f1e59229b9da319d358828cdfa4ddbc140769 ]
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
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -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 bfd42e0853ed..6c88f245b33a 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -4400,7 +4400,7 @@ 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), |