From: Yosry Ahmed <yosry@kernel.org>
Date: Wed, 27 May 2026 23:47:05 +0000 (+0000)
Subject: KVM: x86/pmu: Track mediated PMU counters with mode-specific enables
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=c0d4c9c54c256cea13e3bea82127cc34b833ff08;p=thirdparty%2Fkernel%2Flinux.git

KVM: x86/pmu: Track mediated PMU counters with mode-specific enables

Instead of always checking of a counter needs to be disabled for
mode-specific reasons (e.g. Host-Only/Guest-Only bits in SVM), add a
bitmap to track such counters. Set the bit for counters using either
Host-Only or Guest-Only bits in EVENTSEL on SVM.

This bitmap will also be reused in following changes to selectively
apply changes to such counters.

Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260527234711.4175166-12-yosry@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
---

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index dd761073d618..5934cc3994c5 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -612,6 +612,8 @@ struct kvm_pmu {
 	DECLARE_BITMAP(pmc_counting_instructions, X86_PMC_IDX_MAX);
 	DECLARE_BITMAP(pmc_counting_branches, X86_PMC_IDX_MAX);
 
+	DECLARE_BITMAP(pmc_has_mode_specific_enables, X86_PMC_IDX_MAX);
+
 	u64 ds_area;
 	u64 pebs_enable;
 	u64 pebs_enable_rsvd;
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 8159b07e9bc2..84c834ad2cd4 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -936,6 +936,7 @@ static void kvm_pmu_reset(struct kvm_vcpu *vcpu)
 	pmu->need_cleanup = false;
 
 	bitmap_zero(pmu->reprogram_pmi, X86_PMC_IDX_MAX);
+	bitmap_zero(pmu->pmc_has_mode_specific_enables, X86_PMC_IDX_MAX);
 
 	kvm_for_each_pmc(pmu, pmc, i, pmu->all_valid_pmc_idx) {
 		pmc_stop_counter(pmc);
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index 71c7853e8ae5..34c3c6913ef6 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -202,8 +202,13 @@ static inline bool pmc_is_locally_enabled(struct kvm_pmc *pmc)
 					pmc->idx - KVM_FIXED_PMC_BASE_IDX) &
 					(INTEL_FIXED_0_KERNEL | INTEL_FIXED_0_USER);
 
-	return (pmc->eventsel & ARCH_PERFMON_EVENTSEL_ENABLE) &&
-	       !kvm_pmu_call(pmc_is_disabled_in_current_mode)(pmc);
+	if (!(pmc->eventsel & ARCH_PERFMON_EVENTSEL_ENABLE))
+		return false;
+
+	if (!test_bit(pmc->idx, pmu->pmc_has_mode_specific_enables))
+		return true;
+
+	return !kvm_pmu_call(pmc_is_disabled_in_current_mode)(pmc);
 }
 
 extern struct x86_pmu_capability kvm_pmu_cap;
diff --git a/arch/x86/kvm/svm/pmu.c b/arch/x86/kvm/svm/pmu.c
index 41ee6532290e..b892a25ea4ca 100644
--- a/arch/x86/kvm/svm/pmu.c
+++ b/arch/x86/kvm/svm/pmu.c
@@ -168,6 +168,12 @@ static int amd_pmu_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 			pmc->eventsel = data;
 			pmc->eventsel_hw = (data & ~AMD64_EVENTSEL_HOSTONLY) |
 					   AMD64_EVENTSEL_GUESTONLY;
+
+			if (data & AMD64_EVENTSEL_HOST_GUEST_MASK)
+				__set_bit(pmc->idx, pmu->pmc_has_mode_specific_enables);
+			else
+				__clear_bit(pmc->idx, pmu->pmc_has_mode_specific_enables);
+
 			kvm_pmu_request_counter_reprogram(pmc);
 		}
 		return 0;