Re: [PATCH v3 14/17] i386: Use CPUCacheInfo.share_level to encode CPUID[4]

["Moger, Babu" <babu.moger@amd.com>]

Hi Zhao,

Hitting this error after this patch.

ERROR:../target/i386/cpu.c:257:max_processor_ids_for_cache: code should
not be reached
Bail out! ERROR:../target/i386/cpu.c:257:max_processor_ids_for_cache: code
should not be reached
Aborted (core dumped)

Looks like share_level for all the caches for AMD is not initialized.

Thanks
Babu

On 8/1/23 05:35, Zhao Liu wrote:
> From: Zhao Liu <zhao1.liu@intel.com>
> 
> CPUID[4].EAX[bits 25:14] is used to represent the cache topology for
> intel CPUs.
> 
> After cache models have topology information, we can use
> CPUCacheInfo.share_level to decide which topology level to be encoded
> into CPUID[4].EAX[bits 25:14].
> 
> And since maximum_processor_id (original "num_apic_ids") is parsed
> based on cpu topology levels, which are verified when parsing smp, it's
> no need to check this value by "assert(num_apic_ids > 0)" again, so
> remove this assert.
> 
> Additionally, wrap the encoding of CPUID[4].EAX[bits 31:26] into a
> helper to make the code cleaner.
> 
> Signed-off-by: Zhao Liu <zhao1.liu@intel.com>
> ---
> Changes since v1:
>  * Use "enum CPUTopoLevel share_level" as the parameter in
>    max_processor_ids_for_cache().
>  * Make cache_into_passthrough case also use
>    max_processor_ids_for_cache() and max_core_ids_in_package() to
>    encode CPUID[4]. (Yanan)
>  * Rename the title of this patch (the original is "i386: Use
>    CPUCacheInfo.share_level to encode CPUID[4].EAX[bits 25:14]").
> ---
>  target/i386/cpu.c | 70 +++++++++++++++++++++++++++++------------------
>  1 file changed, 43 insertions(+), 27 deletions(-)
> 
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index 55aba4889628..c9897c0fe91a 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -234,22 +234,53 @@ static uint8_t cpuid2_cache_descriptor(CPUCacheInfo *cache)
>                         ((t) == UNIFIED_CACHE) ? CACHE_TYPE_UNIFIED : \
>                         0 /* Invalid value */)
>  
> +static uint32_t max_processor_ids_for_cache(X86CPUTopoInfo *topo_info,
> +                                            enum CPUTopoLevel share_level)
> +{
> +    uint32_t num_ids = 0;
> +
> +    switch (share_level) {
> +    case CPU_TOPO_LEVEL_CORE:
> +        num_ids = 1 << apicid_core_offset(topo_info);
> +        break;
> +    case CPU_TOPO_LEVEL_DIE:
> +        num_ids = 1 << apicid_die_offset(topo_info);
> +        break;
> +    case CPU_TOPO_LEVEL_PACKAGE:
> +        num_ids = 1 << apicid_pkg_offset(topo_info);
> +        break;
> +    default:
> +        /*
> +         * Currently there is no use case for SMT and MODULE, so use
> +         * assert directly to facilitate debugging.
> +         */
> +        g_assert_not_reached();
> +    }
> +
> +    return num_ids - 1;
> +}
> +
> +static uint32_t max_core_ids_in_package(X86CPUTopoInfo *topo_info)
> +{
> +    uint32_t num_cores = 1 << (apicid_pkg_offset(topo_info) -
> +                               apicid_core_offset(topo_info));
> +    return num_cores - 1;
> +}
>  
>  /* Encode cache info for CPUID[4] */
>  static void encode_cache_cpuid4(CPUCacheInfo *cache,
> -                                int num_apic_ids, int num_cores,
> +                                X86CPUTopoInfo *topo_info,
>                                  uint32_t *eax, uint32_t *ebx,
>                                  uint32_t *ecx, uint32_t *edx)
>  {
>      assert(cache->size == cache->line_size * cache->associativity *
>                            cache->partitions * cache->sets);
>  
> -    assert(num_apic_ids > 0);
>      *eax = CACHE_TYPE(cache->type) |
>             CACHE_LEVEL(cache->level) |
>             (cache->self_init ? CACHE_SELF_INIT_LEVEL : 0) |
> -           ((num_cores - 1) << 26) |
> -           ((num_apic_ids - 1) << 14);
> +           (max_core_ids_in_package(topo_info) << 26) |
> +           (max_processor_ids_for_cache(topo_info, cache->share_level) << 14);
>  
>      assert(cache->line_size > 0);
>      assert(cache->partitions > 0);
> @@ -6116,56 +6147,41 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
>                  int host_vcpus_per_cache = 1 + ((*eax & 0x3FFC000) >> 14);
>  
>                  if (cores_per_pkg > 1) {
> -                    int addressable_cores_offset =
> -                                                apicid_pkg_offset(&topo_info) -
> -                                                apicid_core_offset(&topo_info);
> -
>                      *eax &= ~0xFC000000;
> -                    *eax |= (1 << addressable_cores_offset - 1) << 26;
> +                    *eax |= max_core_ids_in_package(&topo_info) << 26;
>                  }
>                  if (host_vcpus_per_cache > cpus_per_pkg) {
> -                    int pkg_offset = apicid_pkg_offset(&topo_info);
> -
>                      *eax &= ~0x3FFC000;
> -                    *eax |= (1 << pkg_offset - 1) << 14;
> +                    *eax |=
> +                        max_processor_ids_for_cache(&topo_info,
> +                                                CPU_TOPO_LEVEL_PACKAGE) << 14;
>                  }
>              }
>          } else if (cpu->vendor_cpuid_only && IS_AMD_CPU(env)) {
>              *eax = *ebx = *ecx = *edx = 0;
>          } else {
>              *eax = 0;
> -            int addressable_cores_offset = apicid_pkg_offset(&topo_info) -
> -                                           apicid_core_offset(&topo_info);
> -            int core_offset, die_offset;
>  
>              switch (count) {
>              case 0: /* L1 dcache info */
> -                core_offset = apicid_core_offset(&topo_info);
>                  encode_cache_cpuid4(env->cache_info_cpuid4.l1d_cache,
> -                                    (1 << core_offset),
> -                                    (1 << addressable_cores_offset),
> +                                    &topo_info,
>                                      eax, ebx, ecx, edx);
>                  break;
>              case 1: /* L1 icache info */
> -                core_offset = apicid_core_offset(&topo_info);
>                  encode_cache_cpuid4(env->cache_info_cpuid4.l1i_cache,
> -                                    (1 << core_offset),
> -                                    (1 << addressable_cores_offset),
> +                                    &topo_info,
>                                      eax, ebx, ecx, edx);
>                  break;
>              case 2: /* L2 cache info */
> -                core_offset = apicid_core_offset(&topo_info);
>                  encode_cache_cpuid4(env->cache_info_cpuid4.l2_cache,
> -                                    (1 << core_offset),
> -                                    (1 << addressable_cores_offset),
> +                                    &topo_info,
>                                      eax, ebx, ecx, edx);
>                  break;
>              case 3: /* L3 cache info */
> -                die_offset = apicid_die_offset(&topo_info);
>                  if (cpu->enable_l3_cache) {
>                      encode_cache_cpuid4(env->cache_info_cpuid4.l3_cache,
> -                                        (1 << die_offset),
> -                                        (1 << addressable_cores_offset),
> +                                        &topo_info,
>                                          eax, ebx, ecx, edx);
>                      break;
>                  }

-- 
Thanks
Babu Moger