From: Sean Christopherson <seanjc@xxxxxxxxxx>
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@xxxxxxxxxxxxxxx
Cc: Yang Weijiang <weijiang.yang@xxxxxxxxx>
Cc: Like Xu <like.xu.linux@xxxxxxxxx>
Reported-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Fixes: be635e34c284 ("KVM: vmx/pmu: Expose LBR_FMT in the MSR_IA32_PERF_CAPABILITIES")
Tested-by: Like Xu <likexu@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230128001427.2548858-1-seanjc@xxxxxxxxxx
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/vmx/vmx.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7776,9 +7776,11 @@ static u64 vmx_get_perf_capabilities(voi
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;
