[PATCH] target/i386: do not include undefined bits in the AMD topoext leaf

[Paolo Bonzini]

Commit d7c72735f61 ("target/i386: Add new EPYC CPU versions with updated
cache_info", 2023-05-08) ensured that AMD-defined CPU models did not
have the 'complex_indexing' bit set, but left it set in "-cpu host"
which uses the default ("legacy") cache information.

Reimplement that commit using a CPU feature, so that it can be applied
to all guests using a new machine type, independent of the CPU model.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/cpu.h | 3 +++
 hw/i386/pc.c      | 1 +
 target/i386/cpu.c | 4 ++++
 3 files changed, 8 insertions(+)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 31c9b43849e..c43ac01c794 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -2108,6 +2108,9 @@ struct ArchCPU {
     /* Only advertise CPUID leaves defined by the vendor */
     bool vendor_cpuid_only;
 
+    /* Only advertise TOPOEXT features that AMD defines */
+    bool amd_topoext_features_only;
+
     /* Enable auto level-increase for Intel Processor Trace leave */
     bool intel_pt_auto_level;
 
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 77415064c62..5dff91422ff 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -80,6 +80,7 @@
     { "athlon-" TYPE_X86_CPU, "model-id", "QEMU Virtual CPU version " v, },
 
 GlobalProperty pc_compat_9_0[] = {
+    { TYPE_X86_CPU, "x-amd-topoext-features-only", "false" },
     { TYPE_X86_CPU, "x-l1-cache-per-thread", "false" },
     { TYPE_X86_CPU, "guest-phys-bits", "0" },
     { "sev-guest", "legacy-vm-type", "true" },
diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index a042e6b4edb..c9d8f6339a4 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -6991,6 +6991,9 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, 
uint32_t count,
             *eax = *ebx = *ecx = *edx = 0;
             break;
         }
+        if (cpu->amd_topoext_features_only) {
+            *edx &= CACHE_NO_INVD_SHARING | CACHE_INCLUSIVE;
+        }
         break;
     case 0x8000001E:
         if (cpu->core_id <= 255) {
@@ -8302,6 +8305,7 @@ static Property x86_cpu_properties[] = {
     DEFINE_PROP_STRING("hv-vendor-id", X86CPU, hyperv_vendor),
     DEFINE_PROP_BOOL("cpuid-0xb", X86CPU, enable_cpuid_0xb, true),
     DEFINE_PROP_BOOL("x-vendor-cpuid-only", X86CPU, vendor_cpuid_only, true),
+    DEFINE_PROP_BOOL("x-amd-topoext-features-only", X86CPU, 
amd_topoext_features_only, true),
     DEFINE_PROP_BOOL("lmce", X86CPU, enable_lmce, false),
     DEFINE_PROP_BOOL("l3-cache", X86CPU, enable_l3_cache, true),
     DEFINE_PROP_BOOL("kvm-pv-enforce-cpuid", X86CPU, kvm_pv_enforce_cpuid,
-- 
2.45.2