linux-kernel - [PATCH v2 2/5] KVM: x86/pmu: Disable Host-Only/Guest-Only events as appropriate for vCPU state

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Message-ID: <20260129232835.3710773-3-jmattson@google.com>
Date: Thu, 29 Jan 2026 15:28:07 -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 2/5] KVM: x86/pmu: Disable Host-Only/Guest-Only events as
 appropriate for vCPU state

Update amd_pmu_set_eventsel_hw() to clear the event selector's hardware
enable bit when the PMC should not count based on the guest's Host-Only and
Guest-Only event selector bits and the current vCPU state.

Signed-off-by: Jim Mattson <jmattson@...gle.com>
---
 arch/x86/include/asm/perf_event.h |  2 ++
 arch/x86/kvm/svm/pmu.c            | 18 ++++++++++++++++++
 2 files changed, 20 insertions(+)

diff --git a/arch/x86/include/asm/perf_event.h b/arch/x86/include/asm/perf_event.h
index 0d9af4135e0a..4dfe12053c09 100644
--- a/arch/x86/include/asm/perf_event.h
+++ b/arch/x86/include/asm/perf_event.h
@@ -58,6 +58,8 @@
 #define AMD64_EVENTSEL_INT_CORE_ENABLE			(1ULL << 36)
 #define AMD64_EVENTSEL_GUESTONLY			(1ULL << 40)
 #define AMD64_EVENTSEL_HOSTONLY				(1ULL << 41)
+#define AMD64_EVENTSEL_HOST_GUEST_MASK			\
+	(AMD64_EVENTSEL_HOSTONLY | AMD64_EVENTSEL_GUESTONLY)
 
 #define AMD64_EVENTSEL_INT_CORE_SEL_SHIFT		37
 #define AMD64_EVENTSEL_INT_CORE_SEL_MASK		\
diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
index d9ca633f9f49..8d451110a94d 100644
--- a/arch/x86/kvm/svm/pmu.c
+++ b/arch/x86/kvm/svm/pmu.c
@@ -149,8 +149,26 @@ static int amd_pmu_get_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 
 static void amd_pmu_set_eventsel_hw(struct kvm_pmc *pmc)
 {
+	struct kvm_vcpu *vcpu = pmc->vcpu;
+	u64 host_guest_bits;
+
 	pmc->eventsel_hw = (pmc->eventsel & ~AMD64_EVENTSEL_HOSTONLY) |
 			   AMD64_EVENTSEL_GUESTONLY;
+
+	if (!(pmc->eventsel & ARCH_PERFMON_EVENTSEL_ENABLE))
+		return;
+
+	if (!(vcpu->arch.efer & EFER_SVME))
+		return;
+
+	host_guest_bits = pmc->eventsel & AMD64_EVENTSEL_HOST_GUEST_MASK;
+	if (!host_guest_bits || host_guest_bits == AMD64_EVENTSEL_HOST_GUEST_MASK)
+		return;
+
+	if (!!(host_guest_bits & AMD64_EVENTSEL_GUESTONLY) == is_guest_mode(vcpu))
+		return;
+
+	pmc->eventsel_hw &= ~ARCH_PERFMON_EVENTSEL_ENABLE;
 }
 
 static int amd_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
-- 
2.53.0.rc1.225.gd81095ad13-goog