From: Zide Chen <zide.chen@intel.com>
To: Sean Christopherson <seanjc@google.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Peter Zijlstra <peterz@infradead.org>
Cc: kvm@vger.kernel.org, Jim Mattson <jmattson@google.com>,
Yosry Ahmed <yosry@kernel.org>, Andi Kleen <ak@linux.intel.com>,
Stephane Eranian <eranian@google.com>,
linux-kernel@vger.kernel.org, Mingwei Zhang <mizhang@google.com>,
Zide Chen <zide.chen@intel.com>,
Das Sandipan <Sandipan.Das@amd.com>,
Shukla Manali <Manali.Shukla@amd.com>,
Dapeng Mi <dapeng1.mi@linux.intel.com>,
Xudong Hao <xudong.hao@intel.com>
Subject: [PATCH v4 15/21] KVM: x86/pmu: Clamp pmu->version to kvm_pmu_cap.version
Date: Thu, 12 Nov 2026 13:32:21 -0700 [thread overview]
Message-ID: <20261112203227.289379-16-zide.chen@intel.com> (raw)
In-Reply-To: <20261112203227.289379-1-zide.chen@intel.com>
KVM's policy of not policing guest CPUID allows userspace to configure
an arbitrary PMU version without KVM rejecting the ioctl or mutating
guest CPUID entries. As userspace is responsible for validating its
configuration against KVM_GET_SUPPORTED_CPUID, userspace is entitled to
"shoot itself in the foot" by presenting an unsupported virtual CPU
model.
Clamp pmu->version to kvm_pmu_cap.version so that KVM's internal state
tracks the effective PMU version that KVM supports, and avoid exposing
or emulating features that KVM does not support (such as MSRs gated on
higher PMU versions).
Suggested-by: Sean Christopherson <seanjc@google.com>
Suggested-by: Yosry Ahmed <yosry@kernel.org>
Signed-off-by: Zide Chen <zide.chen@intel.com>
---
v4:
- New patch. (Sean, Yosry)
---
arch/x86/kvm/vmx/pmu_intel.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index 5eac64ba8832..0be9956810ae 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -574,7 +574,7 @@ static void intel_pmu_refresh(struct kvm_vcpu *vcpu)
eax.full = entry->eax;
edx.full = entry->edx;
- pmu->version = eax.split.version_id;
+ pmu->version = min_t(int, eax.split.version_id, kvm_pmu_cap.version);
if (!pmu->version)
return;
--
2.56.1
next prev parent reply other threads:[~2026-11-12 20:43 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-12 20:32 [PATCH v4 00/21] KVM: x86/pmu: Add mediated vPMU PerfMon v5 support Zide Chen
2026-11-12 20:32 ` [PATCH v4 01/21] KVM: SVM: Drop counter MSR checks in amd_is_valid_msr() Zide Chen
2026-11-12 20:32 ` [PATCH v4 02/21] KVM: x86/pmu: Remove redundant Perf Global Status MSR bit definitions Zide Chen
2026-11-12 20:32 ` [PATCH v4 03/21] KVM: x86/pmu: Rename all_valid_pmc_idx to pmc_exists Zide Chen
2026-11-12 20:32 ` [PATCH v4 04/21] KVM: x86/pmu: Rename reserved_bits to eventsel_rsvd in kvm_pmu Zide Chen
2026-11-12 20:32 ` [PATCH v4 05/21] KVM: x86/pmu: Use pmc_exists in PMC lookup helpers Zide Chen
2026-11-12 20:32 ` [PATCH v4 06/21] KVM: x86/pmu: Drop nr_arch_{gp,fixed}_counters from kvm_pmu Zide Chen
2026-11-12 20:32 ` [PATCH v4 07/21] KVM: x86/pmu: Expose kvm_host_pmu to vendor modules Zide Chen
2026-11-12 20:32 ` [PATCH v4 08/21] perf/x86: Plumb counter bitmap from x86_pmu to x86_pmu_cap Zide Chen
2026-11-12 20:32 ` [PATCH v4 09/21] KVM: x86/pmu: Switch to bitmask-based KVM PMU capabilities Zide Chen
2026-11-12 20:32 ` [PATCH v4 10/21] perf/x86: Remove num_counters_{gp,fixed} from x86_pmu_capability Zide Chen
2026-11-12 20:32 ` [PATCH v4 11/21] KVM: x86/pmu: Document GLOBAL_STATUS_RESET passthrough erratum Zide Chen
2026-11-12 20:32 ` [PATCH v4 12/21] KVM: x86/pmu: Mark CondChgd reserved in global_status_rsvd Zide Chen
2026-11-12 20:32 ` [PATCH v4 13/21] KVM: x86/pmu: Emulate IA32_PERF_GLOBAL_STATUS_SET MSR Zide Chen
2026-11-12 20:32 ` [PATCH v4 14/21] KVM: x86/pmu: Emulate IA32_PERF_GLOBAL_INUSE MSR Zide Chen
2026-11-12 20:32 ` Zide Chen [this message]
2026-11-12 20:32 ` [PATCH v4 16/21] KVM: x86/pmu: Populate CPUID.0AH:ECX fixed-counter bitmap Zide Chen
2026-11-12 20:32 ` [PATCH v4 17/21] KVM: x86/pmu: Factor out fixed counter control bit calculation Zide Chen
2026-11-12 20:32 ` [PATCH v4 18/21] KVM: x86/pmu: Mask only OS/USR bits when filtering fixed counters Zide Chen
2026-11-12 20:32 ` [PATCH v4 19/21] KVM: x86/pmu: Ignore AnyThread bit if CPUID.0AH:EDX[15] is set Zide Chen
2026-11-12 20:32 ` [PATCH v4 20/21] KVM: x86/pmu: Advertise PerfMon version 5 on Intel hosts Zide Chen
2026-11-12 20:32 ` [PATCH v4 21/21] KVM: selftests: Support fixed counters bitmap in pmu_counters_test Zide Chen
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