i386/cpu: Use APIC ID info get NumSharingCache for CPUID[0x8000001D].EAX[bits 25:14]
The commit 8f4202fb1080 ("i386: Populate AMD Processor Cache Information
for cpuid 0x8000001D") adds the cache topology for AMD CPU by encoding
the number of sharing threads directly.
From AMD's APM, NumSharingCache (CPUID[0x8000001D].EAX[bits 25:14])
means [1]:
The number of logical processors sharing this cache is the value of
this field incremented by 1. To determine which logical processors are
sharing a cache, determine a Share Id for each processor as follows:
ShareId = LocalApicId >> log2(NumSharingCache+1)
Logical processors with the same ShareId then share a cache. If
NumSharingCache+1 is not a power of two, round it up to the next power
of two.
From the description above, the calculation of this field should be same
as CPUID[4].EAX[bits 25:14] for Intel CPUs. So also use the offsets of
APIC ID to calculate this field.
[1]: APM, vol.3, appendix.E.4.15 Function 8000_001Dh--Cache Topology
Information
Tested-by: Yongwei Ma <yongwei.ma@intel.com>
Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Reviewed-by: Xiaoyao Li <xiaoyao.li@intel.com>
Message-ID: <20240424154929.1487382-8-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 f3d2b80..22a8ca1 100644
--- a/target/i386/cpu.c
+++ b/target/i386/cpu.c
@@ -331,7 +331,7 @@
uint32_t *eax, uint32_t *ebx,
uint32_t *ecx, uint32_t *edx)
{
- uint32_t l3_threads;
+ uint32_t num_sharing_cache;
assert(cache->size == cache->line_size * cache->associativity *
cache->partitions * cache->sets);
@@ -340,11 +340,11 @@
/* L3 is shared among multiple cores */
if (cache->level == 3) {
- l3_threads = topo_info->cores_per_die * topo_info->threads_per_core;
- *eax |= (l3_threads - 1) << 14;
+ num_sharing_cache = 1 << apicid_die_offset(topo_info);
} else {
- *eax |= ((topo_info->threads_per_core - 1) << 14);
+ num_sharing_cache = 1 << apicid_core_offset(topo_info);
}
+ *eax |= (num_sharing_cache - 1) << 14;
assert(cache->line_size > 0);
assert(cache->partitions > 0);
