linux-kernel - [PATCH V5 04/10] KVM: x86: Explicitly zero cpuid "0xa" leaf when PMU is disabled

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Date:   Mon, 10 Apr 2023 18:50:50 +0800
From:   Like Xu <like.xu.linux@...il.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH V5 04/10] KVM: x86: Explicitly zero cpuid "0xa" leaf when PMU is disabled

From: Like Xu <likexu@...cent.com>

Add an explicit !enable_pmu check as relying on kvm_pmu_cap to be
zeroed isn't obvious. Although when !enable_pmu, KVM will have
zero-padded kvm_pmu_cap to do subsequent CPUID leaf assignments.

Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Like Xu <likexu@...cent.com>
---
 arch/x86/kvm/cpuid.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index b736ddb42088..52a7acf2c965 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -970,7 +970,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 		union cpuid10_eax eax;
 		union cpuid10_edx edx;
 
-		if (!static_cpu_has(X86_FEATURE_ARCH_PERFMON)) {
+		if (!enable_pmu || !static_cpu_has(X86_FEATURE_ARCH_PERFMON)) {
 			entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
 			break;
 		}
-- 
2.40.0