target/i386: Don't construct a all-zero entry for CPUID[0xD 0x3f]

Currently, QEMU always constructs a all-zero CPUID entry for
CPUID[0xD 0x3f].

It's meaningless to construct such a leaf as the end of leaf 0xD. Rework
the logic of how subleaves of 0xD are constructed to get rid of such
all-zero value of subleaf 0x3f.

Signed-off-by: Xiaoyao Li <xiaoyao.li@intel.com>
Link: https://lore.kernel.org/r/20240814075431.339209-2-xiaoyao.li@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index e6f94900f3c1841804f8665a7d3220aada2f7b57..6f6301460d4522d2503d36e20598ec8813bfb3df 100644 (file)
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -1864,10 +1864,6 @@ static uint32_t kvm_x86_build_cpuid(CPUX86State *env,
         case 0xb:
         case 0xd:
             for (j = 0; ; j++) {
-                if (i == 0xd && j == 64) {
-                    break;
-                }
-
                 c->function = i;
                 c->flags = KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
                 c->index = j;
@@ -1883,7 +1879,12 @@ static uint32_t kvm_x86_build_cpuid(CPUX86State *env,
                     break;
                 }
                 if (i == 0xd && c->eax == 0) {
-                    continue;
+                    if (j < 63) {
+                        continue;
+                    } else {
+                        cpuid_i--;
+                        break;
+                    }
                 }
                 if (cpuid_i == KVM_MAX_CPUID_ENTRIES) {
                     goto full;