Messages in this thread Patch in this message | | | From | Sandipan Das <> | Subject | [PATCH 7/7] kvm: x86/cpuid: Fix Architectural Performance Monitoring support | Date | Thu, 17 Mar 2022 11:58:36 +0530 |
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CPUID 0xA provides information on Architectural Performance Monitoring features on some x86 processors. It advertises a PMU version which Qemu uses to determine the availability of additional MSRs to manage the PMCs.
Upon receiving a KVM_GET_SUPPORTED_CPUID ioctl request for the same, the kernel constructs return values based on the x86_pmu_capability irrespective of the vendor.
This CPUID function and additional MSRs are not supported on AMD processors. If PerfMonV2 is detected, the PMU version is set to 2 and guest startup breaks because of an attempt to access a non-existent MSR. Return zeros to avoid this.
Fixes: a6c06ed1a60a ("KVM: Expose the architectural performance monitoring CPUID leaf") Reported-by: Vasant Hegde <vasant.hegde@amd.com> Signed-off-by: Sandipan Das <sandipan.das@amd.com> --- arch/x86/kvm/cpuid.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index b8f8d268d058..1d9ca5726167 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -865,6 +865,11 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function) union cpuid10_eax eax; union cpuid10_edx edx; + if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) { + entry->eax = entry->ebx = entry->ecx = entry->edx = 0; + break; + } + perf_get_x86_pmu_capability(&cap); /* -- 2.32.0
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