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authorSandipan Das <sandipan.das@amd.com>2022-04-27 17:01:49 +0530
committerPaolo Bonzini <pbonzini@redhat.com>2022-05-03 08:05:08 -0400
commit5a1bde46f98b893cda6122b00e94c0c40a6ead3c (patch)
tree39a40f4c2e24ecc37f7d72a67f6f75692eaf32b0 /arch/x86/kvm
parent5eb849322d7f7ae9d5c587c7bc3b4f7c6872cd2f (diff)
downloadlinux-5a1bde46f98b893cda6122b00e94c0c40a6ead3c.tar.bz2
kvm: x86/cpuid: Only provide CPUID leaf 0xA if host has architectural PMU
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 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> Message-Id: <3fef83d9c2b2f7516e8ff50d60851f29a4bcb716.1651058600.git.sandipan.das@amd.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch/x86/kvm')
-rw-r--r--arch/x86/kvm/cpuid.c5
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index b24ca7f4ed7c..732724ea5b10 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -887,6 +887,11 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
union cpuid10_eax eax;
union cpuid10_edx edx;
+ if (!static_cpu_has(X86_FEATURE_ARCH_PERFMON)) {
+ entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
+ break;
+ }
+
perf_get_x86_pmu_capability(&cap);
/*