linux-kernel - [PATCH 04/15] KVM: PMU: disable LBR handling if architectural LBR is available

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Date:   Wed, 31 Aug 2022 18:34:27 -0400
From:   Yang Weijiang <weijiang.yang@...el.com>
To:     pbonzini@...hat.com, seanjc@...gle.com, kvm@...r.kernel.org
Cc:     like.xu.linux@...il.com, kan.liang@...ux.intel.com,
        wei.w.wang@...el.com, linux-kernel@...r.kernel.org
Subject: [PATCH 04/15] KVM: PMU: disable LBR handling if architectural LBR is available

From: Paolo Bonzini <pbonzini@...hat.com>

Traditional LBR is absent on CPU models that have architectural LBR, so
disable all processing of traditional LBR MSRs if they are not there.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/vmx/pmu_intel.c | 32 ++++++++++++++++++++++----------
 1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/arch/x86/kvm/vmx/pmu_intel.c b/arch/x86/kvm/vmx/pmu_intel.c
index c399637a3a79..89cb75bb0280 100644
--- a/arch/x86/kvm/vmx/pmu_intel.c
+++ b/arch/x86/kvm/vmx/pmu_intel.c
@@ -174,19 +174,23 @@ static inline struct kvm_pmc *get_fw_gp_pmc(struct kvm_pmu *pmu, u32 msr)
 static bool intel_pmu_is_valid_lbr_msr(struct kvm_vcpu *vcpu, u32 index)
 {
 	struct x86_pmu_lbr *records = vcpu_to_lbr_records(vcpu);
-	bool ret = false;
 
 	if (!intel_pmu_lbr_is_enabled(vcpu))
-		return ret;
+		return false;
 
-	ret = (index == MSR_LBR_SELECT) || (index == MSR_LBR_TOS) ||
-		(index >= records->from && index < records->from + records->nr) ||
-		(index >= records->to && index < records->to + records->nr);
+	if (!guest_cpuid_has(vcpu, X86_FEATURE_ARCH_LBR) &&
+	    (index == MSR_LBR_SELECT || index == MSR_LBR_TOS))
+		return true;
 
-	if (!ret && records->info)
-		ret = (index >= records->info && index < records->info + records->nr);
+	if ((index >= records->from && index < records->from + records->nr) ||
+	    (index >= records->to && index < records->to + records->nr))
+		return true;
 
-	return ret;
+	if (records->info && index >= records->info &&
+	    index < records->info + records->nr)
+		return true;
+
+	return false;
 }
 
 static bool intel_is_valid_msr(struct kvm_vcpu *vcpu, u32 msr)
@@ -703,6 +707,9 @@ static void vmx_update_intercept_for_lbr_msrs(struct kvm_vcpu *vcpu, bool set)
 			vmx_set_intercept_for_msr(vcpu, lbr->info + i, MSR_TYPE_RW, set);
 	}
 
+	if (guest_cpuid_has(vcpu, X86_FEATURE_ARCH_LBR))
+		return;
+
 	vmx_set_intercept_for_msr(vcpu, MSR_LBR_SELECT, MSR_TYPE_RW, set);
 	vmx_set_intercept_for_msr(vcpu, MSR_LBR_TOS, MSR_TYPE_RW, set);
 }
@@ -743,10 +750,12 @@ void vmx_passthrough_lbr_msrs(struct kvm_vcpu *vcpu)
 {
 	struct kvm_pmu *pmu = vcpu_to_pmu(vcpu);
 	struct lbr_desc *lbr_desc = vcpu_to_lbr_desc(vcpu);
+	bool lbr_enable = !guest_cpuid_has(vcpu, X86_FEATURE_ARCH_LBR) &&
+		(vmcs_read64(GUEST_IA32_DEBUGCTL) & DEBUGCTLMSR_LBR);
 
 	if (!lbr_desc->event) {
 		vmx_disable_lbr_msrs_passthrough(vcpu);
-		if (vmcs_read64(GUEST_IA32_DEBUGCTL) & DEBUGCTLMSR_LBR)
+		if (lbr_enable)
 			goto warn;
 		if (test_bit(INTEL_PMC_IDX_FIXED_VLBR, pmu->pmc_in_use))
 			goto warn;
@@ -769,7 +778,10 @@ void vmx_passthrough_lbr_msrs(struct kvm_vcpu *vcpu)
 
 static void intel_pmu_cleanup(struct kvm_vcpu *vcpu)
 {
-	if (!(vmcs_read64(GUEST_IA32_DEBUGCTL) & DEBUGCTLMSR_LBR))
+	bool lbr_enable = !guest_cpuid_has(vcpu, X86_FEATURE_ARCH_LBR) &&
+		(vmcs_read64(GUEST_IA32_DEBUGCTL) & DEBUGCTLMSR_LBR);
+
+	if (!lbr_enable)
 		intel_pmu_release_guest_lbr_event(vcpu);
 }
 
-- 
2.27.0