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KVM: x86/pmu: Disallow legacy LBRs if architectural LBRs are available

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commit 098f4c061e upstream.

Disallow enabling LBR support if the CPU supports architectural LBRs.
Traditional LBR support is absent on CPU models that have architectural
LBRs, and KVM doesn't yet support arch LBRs, i.e. KVM will pass through
non-existent MSRs if userspace enables LBRs for the guest.

Cc: stable@vger.kernel.org
Cc: Yang Weijiang <weijiang.yang@intel.com>
Cc: Like Xu <like.xu.linux@gmail.com>
Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Fixes: be635e34c2 ("KVM: vmx/pmu: Expose LBR_FMT in the MSR_IA32_PERF_CAPABILITIES")
Tested-by: Like Xu <likexu@tencent.com>
Link: https://lore.kernel.org/r/20230128001427.2548858-1-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sean Christopherson 2023-01-28 00:14:27 +00:00 committed by Greg Kroah-Hartman
parent d9bad836cf
commit 97fe96c75e
1 changed files with 5 additions and 3 deletions
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8
arch/x86/kvm/vmx/vmx.c
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@ -7776,9 +7776,11 @@ static u64 vmx_get_perf_capabilities(void)
if (boot_cpu_has(X86_FEATURE_PDCM))
rdmsrl(MSR_IA32_PERF_CAPABILITIES, host_perf_cap);
x86_perf_get_lbr(&lbr);
if (lbr.nr)
perf_cap |= host_perf_cap & PMU_CAP_LBR_FMT;
if (!cpu_feature_enabled(X86_FEATURE_ARCH_LBR)) {
x86_perf_get_lbr(&lbr);
if (lbr.nr)
perf_cap |= host_perf_cap & PMU_CAP_LBR_FMT;
}
if (vmx_pebs_supported()) {
perf_cap |= host_perf_cap & PERF_CAP_PEBS_MASK;