From 9a085c4b4adeec648d6506316b8a42fbd0cf7c3c Mon Sep 17 00:00:00 2001 From: Zhao Liu Date: Wed, 24 Apr 2024 23:49:15 +0800 Subject: [PATCH] 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 Signed-off-by: Zhao Liu Reviewed-by: Babu Moger Tested-by: Babu Moger Reviewed-by: Xiaoyao Li Message-ID: <20240424154929.1487382-8-zhao1.liu@intel.com> Signed-off-by: Paolo Bonzini --- target/i386/cpu.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/target/i386/cpu.c b/target/i386/cpu.c index f3d2b8053b2..22a8ca1c9b4 100644 --- a/target/i386/cpu.c +++ b/target/i386/cpu.c @@ -331,7 +331,7 @@ static void encode_cache_cpuid8000001d(CPUCacheInfo *cache, 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 @@ static void encode_cache_cpuid8000001d(CPUCacheInfo *cache, /* 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); -- 2.39.5