[PATCH v4 5/6] KVM: x86/pmu: Allow Host-Only/Guest-Only bits with nSVM and mediated PMU

Yosry Ahmed
2026-03-26T03:12:33Z

From: Jim Mattson <jmattson@google.com>

Now that KVM correctly handles Host-Only and Guest-Only bits in the
event selector MSRs, allow the guest to set them if the vCPU advertises
SVM and uses the mediated PMU.

Signed-off-by: Jim Mattson <jmattson@google.com>
Signed-off-by: Yosry Ahmed <yosry@kernel.org>
---
arch/x86/kvm/svm/pmu.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
index cc1eabb0ad15f..3c04e8da24d33 100644
--- a/arch/x86/kvm/svm/pmu.c
+++ b/arch/x86/kvm/svm/pmu.c
@@ -207,7 +207,11 @@ static void amd_pmu_refresh(struct kvm_vcpu *vcpu)
}

pmu->counter_bitmask[KVM_PMC_GP] = BIT_ULL(48) - 1;
+
pmu->reserved_bits = 0xfffffff000280000ull;
+ if (guest_cpu_cap_has(vcpu, X86_FEATURE_SVM) && kvm_vcpu_has_mediated_pmu(vcpu))
+ pmu->reserved_bits &= ~AMD64_EVENTSEL_HOST_GUEST_MASK;
+
pmu->raw_event_mask = AMD64_RAW_EVENT_MASK;
/* not applicable to AMD; but clean them to prevent any fall out */
pmu->counter_bitmask[KVM_PMC_FIXED] = 0;
--
2.53.0.1018.g2bb0e51243-goog