Re: [PATCH v3 16/17] i386: Use CPUCacheInfo.share_level to encode CPUID[0x8000001D].EAX[bits 25:14]

[Moger, Babu]

Hi Zhao,
  Please copy the thread to kvm@vger.kernel.org also.  It makes it easier
to browse.


On 8/1/23 05:35, Zhao Liu wrote:
> From: Zhao Liu <zhao1.liu@intel.com>
> 
> CPUID[0x8000001D].EAX[bits 25:14] is used to represent the cache
> topology for amd CPUs.
Please change this to.


CPUID[0x8000001D].EAX[bits 25:14] NumSharingCache: number of logical
processors sharing cache. The number of
logical processors sharing this cache is NumSharingCache + 1.

> 
> After cache models have topology information, we can use
> CPUCacheInfo.share_level to decide which topology level to be encoded
> into CPUID[0x8000001D].EAX[bits 25:14].
> 
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> ---
> Changes since v1:
>  * Use cache->share_level as the parameter in
>    max_processor_ids_for_cache().
> ---
>  target/i386/cpu.c | 10 +---------
>  1 file changed, 1 insertion(+), 9 deletions(-)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index f67b6be10b8d..6eee0274ade4 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -361,20 +361,12 @@ static void encode_cache_cpuid8000001d(CPUCacheInfo 
> *cache,
>                                         uint32_t *eax, uint32_t *ebx,
>                                         uint32_t *ecx, uint32_t *edx)
>  {
> -    uint32_t num_apic_ids;
>      assert(cache->size == cache->line_size * cache->associativity *
>                            cache->partitions * cache->sets);
>  
>      *eax = CACHE_TYPE(cache->type) | CACHE_LEVEL(cache->level) |
>                 (cache->self_init ? CACHE_SELF_INIT_LEVEL : 0);
> -
> -    /* L3 is shared among multiple cores */
> -    if (cache->level == 3) {
> -        num_apic_ids = 1 << apicid_die_offset(topo_info);
> -    } else {
> -        num_apic_ids = 1 << apicid_core_offset(topo_info);
> -    }
> -    *eax |= (num_apic_ids - 1) << 14;
> +    *eax |= max_processor_ids_for_cache(topo_info, cache->share_level) << 14;
>  
>      assert(cache->line_size > 0);
>      assert(cache->partitions > 0);

-- 
Thanks
Babu Moger