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Re: [PATCH v6 10/10] i386: Simplify CPUID_8000_001E for AMD
From: |
Igor Mammedov |
Subject: |
Re: [PATCH v6 10/10] i386: Simplify CPUID_8000_001E for AMD |
Date: |
Tue, 1 Sep 2020 13:58:11 +0200 |
On Mon, 31 Aug 2020 13:43:07 -0500
Babu Moger <babu.moger@amd.com> wrote:
> apic_id contains all the information required to build
> CPUID_8000_001E. core_id and node_id is already part of
> apic_id generated by x86_topo_ids_from_apicid.
>
> Also remove the restriction on number bits on core_id and
> node_id.
>
> Remove all the hardcoded values and replace with generalized
> fields.
>
> Refer the Processor Programming Reference (PPR) documentation
> available from the bugzilla Link below.
>
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=206537
> Signed-off-by: Babu Moger <babu.moger@amd.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
> ---
> target/i386/cpu.c | 195
> ++++++++++++-----------------------------------------
> 1 file changed, 45 insertions(+), 150 deletions(-)
>
> diff --git a/target/i386/cpu.c b/target/i386/cpu.c
> index d434c8545a..ada9ec8f3a 100644
> --- a/target/i386/cpu.c
> +++ b/target/i386/cpu.c
> @@ -338,62 +338,6 @@ 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,
> X86CPUTopoInfo *topo_info,
> @@ -434,107 +378,58 @@ static void encode_cache_cpuid8000001d(CPUCacheInfo
> *cache,
> (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,
> - uint32_t *eax, uint32_t *ebx,
> - uint32_t *ecx, uint32_t *edx)
> +static void encode_topo_cpuid8000001e(X86CPU *cpu, X86CPUTopoInfo *topo_info,
> + uint32_t *eax, uint32_t *ebx,
> + uint32_t *ecx, uint32_t *edx)
> {
> - struct core_topology topo = {0};
> - unsigned long nodes;
> - int shift;
> + X86CPUTopoIDs topo_ids;
> +
> + x86_topo_ids_from_apicid(cpu->apic_id, topo_info, &topo_ids);
>
> - build_core_topology(cs->nr_cores, cpu->core_id, &topo);
> *eax = cpu->apic_id;
> +
> /*
> - * CPUID_Fn8000001E_EBX
> - * 31:16 Reserved
> - * 15:8 Threads per core (The number of threads per core is
> - * Threads per core + 1)
> - * 7:0 Core id (see bit decoding below)
> - * SMT:
> - * 4:3 node id
> - * 2 Core complex id
> - * 1:0 Core id
> - * Non SMT:
> - * 5:4 node id
> - * 3 Core complex id
> - * 1:0 Core id
> + * CPUID_Fn8000001E_EBX [Core Identifiers] (CoreId)
> + * Read-only. Reset: 0000_XXXXh.
> + * See Core::X86::Cpuid::ExtApicId.
> + * Core::X86::Cpuid::CoreId_lthree[1:0]_core[3:0]_thread[1:0];
> + * Bits Description
> + * 31:16 Reserved.
> + * 15:8 ThreadsPerCore: threads per core. Read-only. Reset: XXh.
> + * The number of threads per core is ThreadsPerCore+1.
> + * 7:0 CoreId: core ID. Read-only. Reset: XXh.
> + *
> + * NOTE: CoreId is already part of apic_id. Just use it. We can
> + * use all the 8 bits to represent the core_id here.
> */
> - 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.core_id &
> 0xFF);
> +
> /*
> - * CPUID_Fn8000001E_ECX
> - * 31:11 Reserved
> - * 10:8 Nodes per processor (Nodes per processor is number of nodes + 1)
> - * 7:0 Node id (see bit decoding below)
> - * 2 Socket id
> - * 1:0 Node id
> + * CPUID_Fn8000001E_ECX [Node Identifiers] (NodeId)
> + * Read-only. Reset: 0000_0XXXh.
> + * Core::X86::Cpuid::NodeId_lthree[1:0]_core[3:0]_thread[1:0];
> + * Bits Description
> + * 31:11 Reserved.
> + * 10:8 NodesPerProcessor: Node per processor. Read-only. Reset: XXXb.
> + * ValidValues:
> + * Value Description
> + * 000b 1 node per processor.
> + * 001b 2 nodes per processor.
> + * 010b Reserved.
> + * 011b 4 nodes per processor.
> + * 111b-100b Reserved.
> + * 7:0 NodeId: Node ID. Read-only. Reset: XXh.
> + *
> + * NOTE: Hardware reserves 3 bits for number of nodes per processor.
> + * But users can create more nodes than the actual hardware can
> + * support. To genaralize we can use all the upper 8 bits for nodes.
> + * NodeId is combination of node and socket_id which is already decoded
> + * in apic_id. Just use it by shifting.
> */
> - if (topo.num_nodes <= 4) {
> - *ecx = ((topo.num_nodes - 1) << 8) | (cpu->socket_id << 2) |
> - topo.node_id;
> - } else {
> - /*
> - * Node id fix up. Actual hardware supports up to 4 nodes. But with
> - * more than 32 cores, we may end up with more than 4 nodes.
> - * Node id is a combination of socket id and node id. Only
> requirement
> - * here is that this number should be unique accross the system.
> - * Shift the socket id to accommodate more nodes. We dont expect both
> - * socket id and node id to be big number at the same time. This is
> not
> - * an ideal config but we need to to support it. Max nodes we can
> have
> - * is 32 (255/8) with 8 cores per node and 255 max cores. We only
> need
> - * 5 bits for nodes. Find the left most set bit to represent the
> total
> - * 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;
> - shift = find_last_bit(&nodes, 8);
> - *ecx = ((topo.num_nodes - 1) << 8) | (cpu->socket_id << (shift + 1))
> |
> - topo.node_id;
> - }
> + *ecx = ((topo_info->dies_per_pkg - 1) << 8) |
> + ((cpu->apic_id >> apicid_die_offset(topo_info)) & 0xFF);
> +
> *edx = 0;
> }
>
> @@ -6019,7 +5914,7 @@ 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,
> + encode_topo_cpuid8000001e(cpu, &topo_info,
> eax, ebx, ecx, edx);
> break;
> case 0xC0000000:
>
>
- Re: [PATCH v6 10/10] i386: Simplify CPUID_8000_001E for AMD,
Igor Mammedov <=