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

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 <[email protected]>
Reviewed-by: Jim Mattson <[email protected]>
Message-ID: <[email protected]>
Cc: [email protected]
Signed-off-by: Paolo Bonzini <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
(cherry picked from commit bbf821c35dab3211d6e4229656b4a53e04ca0c4e)
Signed-off-by: Jack Vogel <[email protected]>

Author: sean-jc

arch/x86/kvm/cpuid.c

@@ -1048,8 +1048,8 @@ 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;
@@ -1065,8 +1065,6 @@ 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;
@@ -1384,7 +1382,7 @@ 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)) {