linux-kernel - [PATCH v2 4/5] KVM: x86/pmu: Allow Host-Only/Guest-Only bits with nSVM and mediated PMU

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Message-ID: <20260129232835.3710773-5-jmattson@google.com>
Date: Thu, 29 Jan 2026 15:28:09 -0800
From: Jim Mattson <jmattson@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, 
	Arnaldo Carvalho de Melo <acme@...nel.org>, Namhyung Kim <namhyung@...nel.org>, 
	Mark Rutland <mark.rutland@....com>, 
	Alexander Shishkin <alexander.shishkin@...ux.intel.com>, Jiri Olsa <jolsa@...nel.org>, 
	Ian Rogers <irogers@...gle.com>, Adrian Hunter <adrian.hunter@...el.com>, 
	James Clark <james.clark@...aro.org>, Thomas Gleixner <tglx@...nel.org>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>, 
	Shuah Khan <shuah@...nel.org>, linux-perf-users@...r.kernel.org, 
	linux-kernel@...r.kernel.org, kvm@...r.kernel.org, 
	linux-kselftest@...r.kernel.org
Cc: mizhang@...gle.com, yosryahmed@...gle.com, sandipan.das@....com, 
	Jim Mattson <jmattson@...gle.com>
Subject: [PATCH v2 4/5] KVM: x86/pmu: Allow Host-Only/Guest-Only bits with
 nSVM and mediated PMU

If the vCPU advertises SVM and uses the mediated PMU, allow the guest to
set the Host-Only and Guest-Only bits in the event selector MSRs.

Signed-off-by: Jim Mattson <jmattson@...gle.com>
---
 arch/x86/kvm/svm/pmu.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
index e2a849fc7daa..7de7d8d00427 100644
--- a/arch/x86/kvm/svm/pmu.c
+++ b/arch/x86/kvm/svm/pmu.c
@@ -243,6 +243,9 @@ 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.rc1.225.gd81095ad13-goog