From b951d4924c506d79c830a58ba8dae216e2147702 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Sat, 28 Jan 2023 00:14:27 +0000 Subject: [PATCH] KVM: x86/pmu: Disallow legacy LBRs if architectural LBRs are available [ Upstream commit 098f4c061ea10b777033b71c10bd9fd706820ee9 ] 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: Sasha Levin --- arch/x86/kvm/vmx/vmx.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 8ad5992f6134..5db21d9ef671 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -7714,9 +7714,11 @@ 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; -- 2.34.1