KVM: x86: Advertise host CPUID 0x80000005 in KVM_GET_SUPPORTED_CPUID

Advertise CPUID 0x80000005 (L1 cache and TLB info) to userspace so that
VMMs that reflect KVM_GET_SUPPORTED_CPUID into KVM_SET_CPUID2 will
enumerate sane cache/TLB information to the guest.

CPUID 0x80000006 (L2 cache and TLB and L3 cache info) has been returned
since commit 43d05de ("KVM: pass through CPUID(0x80000006)").
Enumerating both 0x80000005 and 0x80000006 with KVM_GET_SUPPORTED_CPUID
is better than reporting one or the other, and 0x80000005 could be helpful
for VMM to pass it to KVM_SET_CPUID{,2} for the same reason with
0x80000006.

Signed-off-by: Takahiro Itazuri <itazur@amazon.com>
Link: https://lore.kernel.org/all/ZK7NmfKI9xur%2FMop@google.com
Link: https://lore.kernel.org/r/20230712183136.85561-1-itazur@amazon.com
[sean: add link, massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

arch/x86/kvm/cpuid.c

@@ -1151,6 +1151,9 @@ static inline int __do_cpuid_func(struct kvm_cpuid_array *array, u32 function)
 		cpuid_entry_override(entry, CPUID_8000_0001_EDX);
 		cpuid_entry_override(entry, CPUID_8000_0001_ECX);
 		break;
+	case 0x80000005:
+		/*  Pass host L1 cache and TLB info. */
+		break;
 	case 0x80000006:
 		/* Drop reserved bits, pass host L2 cache and TLB info. */
 		entry->edx &= ~GENMASK(17, 16);