Re: [PATCH v4 09/16] target/i386: Cleanup and use the EPYC mode topology functions

[Igor Mammedov <imammedo@redhat.com>]

On Mon, 24 Feb 2020 11:29:37 -0600
Babu Moger <babu.moger@amd.com> wrote:

> On 2/24/20 2:52 AM, Igor Mammedov wrote:
> > On Thu, 13 Feb 2020 12:17:25 -0600
> > Babu Moger <babu.moger@amd.com> wrote:
> >   
> >> Use the new functions from topology.h and delete the unused code. Given the
> >> sockets, nodes, cores and threads, the new functions generate apic id for EPYC
> >> mode. Removes all the hardcoded values.
> >>
> >> Signed-off-by: Babu Moger <babu.moger@amd.com>  
> > 
> > modulo MAX() macro, looks fine to me  
>
> Igor, Sorry. What do you mean here?

I meant s/MAX(topo_info->nodes_per_pkg, 1)/topo_info->nodes_per_pkg/

after it's made sure that topo_info->nodes_per_pkg is always valid.


(I believe I've commented on that somewhere. Series isn't split nicely,
so I've ended up applying it all and then reviewing so comments might
look out of the place sometimes, hopefully next revision will be easier
to review)

> >   
> >> ---
> >>  target/i386/cpu.c |  162 +++++++++++------------------------------------------
> >>  1 file changed, 35 insertions(+), 127 deletions(-)
> >>
> >> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> >> index 5d6edfd09b..19675eb696 100644
> >> --- a/target/i386/cpu.c
> >> +++ b/target/i386/cpu.c
> >> @@ -338,68 +338,15 @@ static void encode_cache_cpuid80000006(CPUCacheInfo *l2,
> >>      }
> >>  }
> >>  
> >> -/*
> >> - * Definitions used for building CPUID Leaf 0x8000001D and 0x8000001E
> >> - * Please refer to the AMD64 Architecture Programmer’s Manual Volume 3.
> >> - * Define the constants to build the cpu topology. Right now, TOPOEXT
> >> - * feature is enabled only on EPYC. So, these constants are based on
> >> - * EPYC supported configurations. We may need to handle the cases if
> >> - * these values change in future.
> >> - */
> >> -/* Maximum core complexes in a node */
> >> -#define MAX_CCX 2
> >> -/* Maximum cores in a core complex */
> >> -#define MAX_CORES_IN_CCX 4
> >> -/* Maximum cores in a node */
> >> -#define MAX_CORES_IN_NODE 8
> >> -/* Maximum nodes in a socket */
> >> -#define MAX_NODES_PER_SOCKET 4
> >> -
> >> -/*
> >> - * Figure out the number of nodes required to build this config.
> >> - * Max cores in a node is 8
> >> - */
> >> -static int nodes_in_socket(int nr_cores)
> >> -{
> >> -    int nodes;
> >> -
> >> -    nodes = DIV_ROUND_UP(nr_cores, MAX_CORES_IN_NODE);
> >> -
> >> -   /* Hardware does not support config with 3 nodes, return 4 in that case */
> >> -    return (nodes == 3) ? 4 : nodes;
> >> -}
> >> -
> >> -/*
> >> - * Decide the number of cores in a core complex with the given nr_cores using
> >> - * following set constants MAX_CCX, MAX_CORES_IN_CCX, MAX_CORES_IN_NODE and
> >> - * MAX_NODES_PER_SOCKET. Maintain symmetry as much as possible
> >> - * L3 cache is shared across all cores in a core complex. So, this will also
> >> - * tell us how many cores are sharing the L3 cache.
> >> - */
> >> -static int cores_in_core_complex(int nr_cores)
> >> -{
> >> -    int nodes;
> >> -
> >> -    /* Check if we can fit all the cores in one core complex */
> >> -    if (nr_cores <= MAX_CORES_IN_CCX) {
> >> -        return nr_cores;
> >> -    }
> >> -    /* Get the number of nodes required to build this config */
> >> -    nodes = nodes_in_socket(nr_cores);
> >> -
> >> -    /*
> >> -     * Divide the cores accros all the core complexes
> >> -     * Return rounded up value
> >> -     */
> >> -    return DIV_ROUND_UP(nr_cores, nodes * MAX_CCX);
> >> -}
> >> -
> >>  /* Encode cache info for CPUID[8000001D] */
> >> -static void encode_cache_cpuid8000001d(CPUCacheInfo *cache, CPUState *cs,
> >> -                                uint32_t *eax, uint32_t *ebx,
> >> -                                uint32_t *ecx, uint32_t *edx)
> >> +static void encode_cache_cpuid8000001d(CPUCacheInfo *cache,
> >> +                                       X86CPUTopoInfo *topo_info,
> >> +                                       uint32_t *eax, uint32_t *ebx,
> >> +                                       uint32_t *ecx, uint32_t *edx)
> >>  {
> >>      uint32_t l3_cores;
> >> +    unsigned nodes = MAX(topo_info->nodes_per_pkg, 1);
> >> +
> >>      assert(cache->size == cache->line_size * cache->associativity *
> >>                            cache->partitions * cache->sets);
> >>  
> >> @@ -408,10 +355,13 @@ static void encode_cache_cpuid8000001d(CPUCacheInfo *cache, CPUState *cs,
> >>  
> >>      /* L3 is shared among multiple cores */
> >>      if (cache->level == 3) {
> >> -        l3_cores = cores_in_core_complex(cs->nr_cores);
> >> -        *eax |= ((l3_cores * cs->nr_threads) - 1) << 14;
> >> +        l3_cores = DIV_ROUND_UP((topo_info->dies_per_pkg *
> >> +                                 topo_info->cores_per_die *
> >> +                                 topo_info->threads_per_core),
> >> +                                 nodes);
> >> +        *eax |= (l3_cores - 1) << 14;
> >>      } else {
> >> -        *eax |= ((cs->nr_threads - 1) << 14);
> >> +        *eax |= ((topo_info->threads_per_core - 1) << 14);
> >>      }
> >>  
> >>      assert(cache->line_size > 0);
> >> @@ -431,55 +381,17 @@ static void encode_cache_cpuid8000001d(CPUCacheInfo *cache, CPUState *cs,
> >>             (cache->complex_indexing ? CACHE_COMPLEX_IDX : 0);
> >>  }
> >>  
> >> -/* Data structure to hold the configuration info for a given core index */
> >> -struct core_topology {
> >> -    /* core complex id of the current core index */
> >> -    int ccx_id;
> >> -    /*
> >> -     * Adjusted core index for this core in the topology
> >> -     * This can be 0,1,2,3 with max 4 cores in a core complex
> >> -     */
> >> -    int core_id;
> >> -    /* Node id for this core index */
> >> -    int node_id;
> >> -    /* Number of nodes in this config */
> >> -    int num_nodes;
> >> -};
> >> -
> >> -/*
> >> - * Build the configuration closely match the EPYC hardware. Using the EPYC
> >> - * hardware configuration values (MAX_CCX, MAX_CORES_IN_CCX, MAX_CORES_IN_NODE)
> >> - * right now. This could change in future.
> >> - * nr_cores : Total number of cores in the config
> >> - * core_id  : Core index of the current CPU
> >> - * topo     : Data structure to hold all the config info for this core index
> >> - */
> >> -static void build_core_topology(int nr_cores, int core_id,
> >> -                                struct core_topology *topo)
> >> -{
> >> -    int nodes, cores_in_ccx;
> >> -
> >> -    /* First get the number of nodes required */
> >> -    nodes = nodes_in_socket(nr_cores);
> >> -
> >> -    cores_in_ccx = cores_in_core_complex(nr_cores);
> >> -
> >> -    topo->node_id = core_id / (cores_in_ccx * MAX_CCX);
> >> -    topo->ccx_id = (core_id % (cores_in_ccx * MAX_CCX)) / cores_in_ccx;
> >> -    topo->core_id = core_id % cores_in_ccx;
> >> -    topo->num_nodes = nodes;
> >> -}
> >> -
> >>  /* Encode cache info for CPUID[8000001E] */
> >> -static void encode_topo_cpuid8000001e(CPUState *cs, X86CPU *cpu,
> >> +static void encode_topo_cpuid8000001e(X86CPUTopoInfo *topo_info, X86CPU *cpu,
> >>                                         uint32_t *eax, uint32_t *ebx,
> >>                                         uint32_t *ecx, uint32_t *edx)
> >>  {
> >> -    struct core_topology topo = {0};
> >> -    unsigned long nodes;
> >> +    X86CPUTopoIDs topo_ids = {0};
> >> +    unsigned long nodes = MAX(topo_info->nodes_per_pkg, 1);
> >>      int shift;
> >>  
> >> -    build_core_topology(cs->nr_cores, cpu->core_id, &topo);
> >> +    x86_topo_ids_from_apicid_epyc(cpu->apic_id, topo_info, &topo_ids);
> >> +
> >>      *eax = cpu->apic_id;
> >>      /*
> >>       * CPUID_Fn8000001E_EBX
> >> @@ -496,12 +408,8 @@ static void encode_topo_cpuid8000001e(CPUState *cs, X86CPU *cpu,
> >>       *             3 Core complex id
> >>       *           1:0 Core id
> >>       */
> >> -    if (cs->nr_threads - 1) {
> >> -        *ebx = ((cs->nr_threads - 1) << 8) | (topo.node_id << 3) |
> >> -                (topo.ccx_id << 2) | topo.core_id;
> >> -    } else {
> >> -        *ebx = (topo.node_id << 4) | (topo.ccx_id << 3) | topo.core_id;
> >> -    }
> >> +    *ebx = ((topo_info->threads_per_core - 1) << 8) | (topo_ids.node_id << 3) |
> >> +            (topo_ids.core_id);
> >>      /*
> >>       * CPUID_Fn8000001E_ECX
> >>       * 31:11 Reserved
> >> @@ -510,9 +418,9 @@ static void encode_topo_cpuid8000001e(CPUState *cs, X86CPU *cpu,
> >>       *         2  Socket id
> >>       *       1:0  Node id
> >>       */
> >> -    if (topo.num_nodes <= 4) {
> >> -        *ecx = ((topo.num_nodes - 1) << 8) | (cpu->socket_id << 2) |
> >> -                topo.node_id;
> >> +
> >> +    if (nodes <= 4) {
> >> +        *ecx = ((nodes - 1) << 8) | (topo_ids.pkg_id << 2) | topo_ids.node_id;
> >>      } else {
> >>          /*
> >>           * Node id fix up. Actual hardware supports up to 4 nodes. But with
> >> @@ -527,10 +435,10 @@ static void encode_topo_cpuid8000001e(CPUState *cs, X86CPU *cpu,
> >>           * number of nodes. find_last_bit returns last set bit(0 based). Left
> >>           * shift(+1) the socket id to represent all the nodes.
> >>           */
> >> -        nodes = topo.num_nodes - 1;
> >> +        nodes -= 1;
> >>          shift = find_last_bit(&nodes, 8);
> >> -        *ecx = ((topo.num_nodes - 1) << 8) | (cpu->socket_id << (shift + 1)) |
> >> -                topo.node_id;
> >> +        *ecx = (nodes << 8) | (topo_ids.pkg_id << (shift + 1)) |
> >> +               topo_ids.node_id;
> >>      }
> >>      *edx = 0;
> >>  }
> >> @@ -5318,6 +5226,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
> >>      uint32_t signature[3];
> >>      X86CPUTopoInfo topo_info;
> >>  
> >> +    topo_info.nodes_per_pkg = env->nr_nodes;
> >>      topo_info.dies_per_pkg = env->nr_dies;
> >>      topo_info.cores_per_die = cs->nr_cores;
> >>      topo_info.threads_per_core = cs->nr_threads;
> >> @@ -5737,20 +5646,20 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
> >>          }
> >>          switch (count) {
> >>          case 0: /* L1 dcache info */
> >> -            encode_cache_cpuid8000001d(env->cache_info_amd.l1d_cache, cs,
> >> -                                       eax, ebx, ecx, edx);
> >> +            encode_cache_cpuid8000001d(env->cache_info_amd.l1d_cache,
> >> +                                       &topo_info, eax, ebx, ecx, edx);
> >>              break;
> >>          case 1: /* L1 icache info */
> >> -            encode_cache_cpuid8000001d(env->cache_info_amd.l1i_cache, cs,
> >> -                                       eax, ebx, ecx, edx);
> >> +            encode_cache_cpuid8000001d(env->cache_info_amd.l1i_cache,
> >> +                                       &topo_info, eax, ebx, ecx, edx);
> >>              break;
> >>          case 2: /* L2 cache info */
> >> -            encode_cache_cpuid8000001d(env->cache_info_amd.l2_cache, cs,
> >> -                                       eax, ebx, ecx, edx);
> >> +            encode_cache_cpuid8000001d(env->cache_info_amd.l2_cache,
> >> +                                       &topo_info, eax, ebx, ecx, edx);
> >>              break;
> >>          case 3: /* L3 cache info */
> >> -            encode_cache_cpuid8000001d(env->cache_info_amd.l3_cache, cs,
> >> -                                       eax, ebx, ecx, edx);
> >> +            encode_cache_cpuid8000001d(env->cache_info_amd.l3_cache,
> >> +                                       &topo_info, eax, ebx, ecx, edx);
> >>              break;
> >>          default: /* end of info */
> >>              *eax = *ebx = *ecx = *edx = 0;
> >> @@ -5759,8 +5668,7 @@ void cpu_x86_cpuid(CPUX86State *env, uint32_t index, uint32_t count,
> >>          break;
> >>      case 0x8000001E:
> >>          assert(cpu->core_id <= 255);
> >> -        encode_topo_cpuid8000001e(cs, cpu,
> >> -                                  eax, ebx, ecx, edx);
> >> +        encode_topo_cpuid8000001e(&topo_info, cpu, eax, ebx, ecx, edx);
> >>          break;
> >>      case 0xC0000000:
> >>          *eax = env->cpuid_xlevel2;
> >>  
> >   
>