kvm: x86: Include multiple indices with CPUID leaf 0x8000001d

Per the APM, "CPUID Fn8000_001D_E[D,C,B,A]X reports cache topology
information for the cache enumerated by the value passed to the
instruction in ECX, referred to as Cache n in the following
description. To gather information for all cache levels, software must
repeatedly execute CPUID with 8000_001Dh in EAX and ECX set to
increasing values beginning with 0 until a value of 00h is returned in
the field CacheType (EAX[4:0]) indicating no more cache descriptions
are available for this processor."

The termination condition is the same as leaf 4, so we can reuse that
code block for leaf 0x8000001d.

Fixes: 8765d753 ("KVM: X86: Extend CPUID range to include new leaf")
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Borislav Petkov <bp@suse.de>
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Marc Orr <marcorr@google.com>
Reviewed-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/cpuid.c

@@ -456,8 +456,9 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 		}
 		break;
 	}
-	/* function 4 has additional index. */
-	case 4: {
+	/* functions 4 and 0x8000001d have additional index. */
+	case 4:
+	case 0x8000001d: {
 		int i, cache_type;
 
 		entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
@@ -702,8 +703,6 @@ static inline int __do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
 		break;
 	case 0x8000001a:
 		break;
-	case 0x8000001d:
-		break;
 	/*Add support for Centaur's CPUID instruction*/
 	case 0xC0000000:
 		/*Just support up to 0xC0000004 now*/