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

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>

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 5e4d4934c0d3c21e536855cbd374d57ff531fd09..571c906ffcbfe2c10b7ef40531ead81f11bedf9f 100644 (file)
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -1427,8 +1427,8 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
                }
                break;
        case 0xa: { /* Architectural Performance Monitoring */
-               union cpuid10_eax eax;
-               union cpuid10_edx edx;
+               union cpuid10_eax eax = { };
+               union cpuid10_edx edx = { };
 
                if (!enable_pmu || !static_cpu_has(X86_FEATURE_ARCH_PERFMON)) {
                        entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
@@ -1444,8 +1444,6 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 
                if (kvm_pmu_cap.version)
                        edx.split.anythread_deprecated = 1;
-               edx.split.reserved1 = 0;
-               edx.split.reserved2 = 0;
 
                entry->eax = eax.full;
                entry->ebx = kvm_pmu_cap.events_mask;
@@ -1763,7 +1761,7 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
                break;
        /* AMD Extended Performance Monitoring and Debug */
        case 0x80000022: {
-               union cpuid_0x80000022_ebx ebx;
+               union cpuid_0x80000022_ebx ebx = { };
 
                entry->ecx = entry->edx = 0;
                if (!enable_pmu || !kvm_cpu_cap_has(X86_FEATURE_PERFMON_V2)) {