The commit 8f4202fb10 ("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>
9a085c4b4a