i386/cpu: Mark CPUID[0x80000005] as reserved for Intel

Per SDM, 0x80000005 leaf is reserved for Intel CPU, and its current
"assert" check blocks adding new cache model for non-AMD CPUs.

And please note, although Zhaoxin mostly follows Intel behavior,
this leaf is an exception [1].

So, with the compat property "x-vendor-cpuid-only-v2", for the machine
since v10.1, check the vendor and encode this leaf as all-0 only for
Intel CPU. In addition, drop lines_per_tag assertion in
encode_cache_cpuid80000005(), since Zhaoxin will use legacy Intel cache
model in this leaf - which doesn't have this field.

This fix also resolves 2 FIXMEs of legacy_l1d_cache_amd and
legacy_l1i_cache_amd:

/*FIXME: CPUID leaf 0x80000005 is inconsistent with leaves 2 & 4 */

In addition, per AMD's APM, update the comment of CPUID[0x80000005].

[1]: https://lore.kernel.org/qemu-devel/fa16f7a8-4917-4731-9d9f-7d4c10977168@zhaoxin.com/

Tested-by: Yi Lai <yi1.lai@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250711102143.1622339-9-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index 630a40d72beaec5722f6fdc4541f8f143fa015f7..2abcb5acffcfafc974d9bf261a0d150d7fa4c99a 100644 (file)
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -499,7 +499,6 @@ static void encode_topo_cpuid1f(CPUX86State *env, uint32_t count,
 static uint32_t encode_cache_cpuid80000005(CPUCacheInfo *cache)
 {
     assert(cache->size % 1024 == 0);
-    assert(cache->lines_per_tag > 0);
     assert(cache->associativity > 0);
     assert(cache->line_size > 0);
     return ((cache->size / 1024) << 24) | (cache->associativity << 16) |
@@ -657,7 +656,6 @@ static CPUCacheInfo legacy_l1d_cache = {
     .share_level = CPU_TOPOLOGY_LEVEL_CORE,
 };
 
-/*FIXME: CPUID leaf 0x80000005 is inconsistent with leaves 2 & 4 */
 static CPUCacheInfo legacy_l1d_cache_amd = {
     .type = DATA_CACHE,
     .level = 1,
@@ -686,7 +684,6 @@ static CPUCacheInfo legacy_l1i_cache = {
     .share_level = CPU_TOPOLOGY_LEVEL_CORE,
 };
 
-/*FIXME: CPUID leaf 0x80000005 is inconsistent with leaves 2 & 4 */
 static CPUCacheInfo legacy_l1i_cache_amd = {
     .type = INSTRUCTION_CACHE,
     .level = 1,
@@ -7884,11 +7881,17 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
         *edx = env->cpuid_model[(index - 0x80000002) * 4 + 3];
         break;
     case 0x80000005:
-        /* cache info (L1 cache) */
+        /* cache info (L1 cache/TLB Associativity Field) */
         if (cpu->cache_info_passthrough) {
             x86_cpu_get_cache_cpuid(index, 0, eax, ebx, ecx, edx);
             break;
         }
+
+        if (cpu->vendor_cpuid_only_v2 && IS_INTEL_CPU(env)) {
+            *eax = *ebx = *ecx = *edx = 0;
+            break;
+        }
+
         *eax = (L1_DTLB_2M_ASSOC << 24) | (L1_DTLB_2M_ENTRIES << 16) |
                (L1_ITLB_2M_ASSOC <<  8) | (L1_ITLB_2M_ENTRIES);
         *ebx = (L1_DTLB_4K_ASSOC << 24) | (L1_DTLB_4K_ENTRIES << 16) |
@@ -9478,6 +9481,7 @@ static const 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-vendor-cpuid-only-v2", X86CPU, vendor_cpuid_only_v2, 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),