From: Sean Christopherson Date: Sat, 28 Jan 2023 00:14:27 +0000 (+0000) Subject: KVM: x86/pmu: Disallow legacy LBRs if architectural LBRs are available X-Git-Tag: v6.2.15~586 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b6594c9a3c52123eeb52d7ffdda56b9067328eba;p=thirdparty%2Fkernel%2Fstable.git KVM: x86/pmu: Disallow legacy LBRs if architectural LBRs are available commit 098f4c061ea10b777033b71c10bd9fd706820ee9 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 Cc: Like Xu Reported-by: Paolo Bonzini Fixes: be635e34c284 ("KVM: vmx/pmu: Expose LBR_FMT in the MSR_IA32_PERF_CAPABILITIES") Tested-by: Like Xu Link: https://lore.kernel.org/r/20230128001427.2548858-1-seanjc@google.com Signed-off-by: Sean Christopherson Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index cb547a0833812..663e8a6f03b3b 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7749,9 +7749,11 @@ 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;