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KVM: x86: Explicitly zero-initialize on-stack CPUID unions

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commit bc52ae0a708cb6fa3926d11c88e3c55e1171b4a1 upstream.

Explicitly zero/empty-initialize the unions used for PMU related CPUID
entries, instead of manually zeroing all fields (hopefully), or in the
case of 0x80000022, relying on the compiler to clobber the uninitialized
bitfields.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Jim Mattson <jmattson@google.com>
Message-ID: <20250315024102.2361628-1-seanjc@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sean Christopherson
2025-03-14 19:41:02 -07:00
committed by Greg Kroah-Hartman
parent 504464fd01
commit 8cb249d56e
1 changed files with 3 additions and 5 deletions
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8
arch/x86/kvm/cpuid.c
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@@ -1011,8 +1011,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
} }
break; break;
case 0xa: { /* Architectural Performance Monitoring */ case 0xa: { /* Architectural Performance Monitoring */
union cpuid10_eax eax; union cpuid10_eax eax = { };
union cpuid10_edx edx; union cpuid10_edx edx = { };
if (!enable_pmu || !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; entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
@@ -1028,8 +1028,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
if (kvm_pmu_cap.version) if (kvm_pmu_cap.version)
edx.split.anythread_deprecated = 1; edx.split.anythread_deprecated = 1;
edx.split.reserved1 = 0;
edx.split.reserved2 = 0;
entry->eax = eax.full; entry->eax = eax.full;
entry->ebx = kvm_pmu_cap.events_mask; entry->ebx = kvm_pmu_cap.events_mask;
@@ -1303,7 +1301,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
break; break;
/* AMD Extended Performance Monitoring and Debug */ /* AMD Extended Performance Monitoring and Debug */
case 0x80000022: { case 0x80000022: {
union cpuid_0x80000022_ebx ebx; union cpuid_0x80000022_ebx ebx = { };
entry->ecx = entry->edx = 0; entry->ecx = entry->edx = 0;
if (!enable_pmu || !kvm_cpu_cap_has(X86_FEATURE_PERFMON_V2)) { if (!enable_pmu || !kvm_cpu_cap_has(X86_FEATURE_PERFMON_V2)) {