Messages in this thread | | | Date | Wed, 27 Apr 2022 15:22:02 +0530 | Subject | Re: [PATCH v3 7/7] kvm: x86/cpuid: Fix CPUID leaf 0xA | From | Sandipan Das <> |
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On 4/27/2022 3:02 PM, Like Xu wrote: > On 26/4/2022 9:05 pm, Sandipan Das wrote: >> On some x86 processors, CPUID leaf 0xA provides information >> on Architectural Performance Monitoring features. 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 leaf and the additional MSRs are not supported on AMD >> and Hygon processors. If AMD PerfMonV2 is detected, the PMU > > So, why not: > > if (!static_cpu_has(X86_FEATURE_ARCH_PERFMON)) > break; > ? >
That seems to be a better option. Thanks for the suggestion! Will change it in the next revision.
>> 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 | 6 ++++++ >> 1 file changed, 6 insertions(+) >> >> diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c >> index 4b62d80bb22f..d27d6a8f601a 100644 >> --- a/arch/x86/kvm/cpuid.c >> +++ b/arch/x86/kvm/cpuid.c >> @@ -872,6 +872,12 @@ 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 || >> + boot_cpu_data.x86_vendor == X86_VENDOR_HYGON) { >> + entry->eax = entry->ebx = entry->ecx = entry->edx = 0; >> + break; >> + } >> + >> perf_get_x86_pmu_capability(&cap); >> /*
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