From: Sandipan Das sandipan.das@amd.com
[ Upstream commit 5a1bde46f98b893cda6122b00e94c0c40a6ead3c ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- 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 6a8db8eb0e94..62c7f771a7cf 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -592,6 +592,11 @@ static inline int __do_cpuid_func(struct kvm_cpuid_entry2 *entry, 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);
/*