[PULL 41/77] i386/cpu: Add descriptor 0x49 for CPUID 0x2 encoding

[Paolo Bonzini <pbonzini@redhat.com>]

From: Zhao Liu <zhao1.liu@intel.com>

The legacy_l2_cache (2nd-level cache: 4 MByte, 16-way set associative,
64 byte line size) corresponds to descriptor 0x49, but at present
cpuid2_cache_descriptors doesn't support descriptor 0x49 because it has
multiple meanings.

The 0x49 is necessary when CPUID 0x2 and 0x4 leaves have the consistent
cache model, and use legacy_l2_cache as the default L2 cache.

Therefore, add descriptor 0x49 to represent general L2 cache.

Reviewed-by: Dapeng Mi <dapeng1.mi@linux.intel.com>
Tested-by: Yi Lai <yi1.lai@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Link: https://lore.kernel.org/r/20250711102143.1622339-3-zhao1.liu@intel.com
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 target/i386/cpu.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/target/i386/cpu.c b/target/i386/cpu.c
index f107e586734..4386b60ff6c 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -129,7 +129,18 @@ struct CPUID2CacheDescriptorInfo cpuid2_cache_descriptors[] = {
                .associativity = 8,  .line_size = 64, },
     [0x48] = { .level = 2, .type = UNIFIED_CACHE,     .size =   3 * MiB,
                .associativity = 12, .line_size = 64, },
-    /* Descriptor 0x49 depends on CPU family/model, so it is not included */
+    /*
+     * Descriptor 0x49 has 2 cases:
+     *  - 2nd-level cache: 4 MByte, 16-way set associative, 64 byte line size.
+     *  - 3rd-level cache: 4MB, 16-way set associative, 64-byte line size
+     *    (Intel Xeon processor MP, Family 0FH, Model 06H).
+     *
+     * When it represents L3, then it depends on CPU family/model. Fortunately,
+     * the legacy cache/CPU models don't have such special L3. So, just add it
+     * to represent the general L2 case.
+     */
+    [0x49] = { .level = 2, .type = UNIFIED_CACHE,     .size =   4 * MiB,
+               .associativity = 16, .line_size = 64, },
     [0x4A] = { .level = 3, .type = UNIFIED_CACHE,     .size =   6 * MiB,
                .associativity = 12, .line_size = 64, },
     [0x4B] = { .level = 3, .type = UNIFIED_CACHE,     .size =   8 * MiB,
-- 
2.50.0