From: Sandipan Das <sandipan.das@amd.com>
To: <linux-kernel@vger.kernel.org>,
<linux-perf-users@vger.kernel.org>, <x86@kernel.org>
Cc: <peterz@infradead.org>, <bp@alien8.de>,
<dave.hansen@linux.intel.com>, <acme@kernel.org>,
<mark.rutland@arm.com>, <alexander.shishkin@linux.intel.com>,
<namhyung@kernel.org>, <jolsa@kernel.org>, <tglx@linutronix.de>,
<mingo@redhat.com>, <pbonzini@redhat.com>, <jmattson@google.com>,
<like.xu.linux@gmail.com>, <eranian@google.com>,
<ananth.narayan@amd.com>, <ravi.bangoria@amd.com>,
<santosh.shukla@amd.com>, <sandipan.das@amd.com>
Subject: [PATCH v2 7/7] kvm: x86/cpuid: Fix CPUID leaf 0xA
Date: Thu, 21 Apr 2022 11:16:59 +0530 [thread overview]
Message-ID: <54bc7fe4cadf6bdef823bab1fba43d4891d2e1a9.1650515382.git.sandipan.das@amd.com> (raw)
In-Reply-To: <cover.1650515382.git.sandipan.das@amd.com>
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
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 4b62d80bb22f..6bd65cad75ef 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -872,6 +872,11 @@ 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
next prev parent reply other threads:[~2022-04-21 5:49 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-21 5:46 [PATCH v2 0/7] perf/x86/amd/core: Add AMD PerfMonV2 support Sandipan Das
2022-04-21 5:46 ` [PATCH v2 1/7] x86/cpufeatures: Add PerfMonV2 feature bit Sandipan Das
2022-04-21 5:46 ` [PATCH v2 2/7] x86/msr: Add PerfCntrGlobal* registers Sandipan Das
2022-04-21 5:46 ` [PATCH v2 3/7] perf/x86/amd/core: Detect PerfMonV2 support Sandipan Das
2022-04-21 5:46 ` [PATCH v2 4/7] perf/x86/amd/core: Detect available counters Sandipan Das
2022-04-21 5:46 ` [PATCH v2 5/7] perf/x86/amd/core: Add PerfMonV2 counter control Sandipan Das
2022-04-21 5:46 ` [PATCH v2 6/7] perf/x86/amd/core: Add PerfMonV2 overflow handling Sandipan Das
2022-04-21 5:46 ` Sandipan Das [this message]
2022-04-26 8:15 ` [PATCH v2 7/7] kvm: x86/cpuid: Fix CPUID leaf 0xA Peter Zijlstra
2022-04-26 8:40 ` Sandipan Das
2022-04-26 11:45 ` Wen Pu
2022-04-26 12:39 ` Peter Zijlstra
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