include/hw/i386/topology.h

   1 /*
   2  *  x86 CPU topology data structures and functions
   3  *
   4  *  Copyright (c) 2012 Red Hat Inc.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a copy
   7  * of this software and associated documentation files (the "Software"), to deal
   8  * in the Software without restriction, including without limitation the rights
   9  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  10  * copies of the Software, and to permit persons to whom the Software is
  11  * furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included in
  14  * all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  21  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  22  * THE SOFTWARE.
  23  */
  24 #ifndef HW_I386_TOPOLOGY_H
  25 #define HW_I386_TOPOLOGY_H
  26
  27 /* This file implements the APIC-ID-based CPU topology enumeration logic,
  28  * documented at the following document:
  29  *   Intel® 64 Architecture Processor Topology Enumeration
  30  *   http://software.intel.com/en-us/articles/intel-64-architecture-processor-topology-enumeration/
  31  *
  32  * This code should be compatible with AMD's "Extended Method" described at:
  33  *   AMD CPUID Specification (Publication #25481)
  34  *   Section 3: Multiple Core Calcuation
  35  * as long as:
  36  *  nr_threads is set to 1;
  37  *  OFFSET_IDX is assumed to be 0;
  38  *  CPUID Fn8000_0008_ECX[ApicIdCoreIdSize[3:0]] is set to apicid_core_width().
  39  */
  40
  41 #include <stdint.h>
  42 #include <string.h>
  43
  44 #include "qemu/bitops.h"
  45
  46 /* APIC IDs can be 32-bit, but beware: APIC IDs > 255 require x2APIC support
  47  */
  48 typedef uint32_t apic_id_t;
  49
  50 /* Return the bit width needed for 'count' IDs
  51  */
  52 static unsigned apicid_bitwidth_for_count(unsigned count)
  53 {
  54     g_assert(count >= 1);
  55     count -= 1;
  56     return count ? 32 - clz32(count) : 0;
  57 }
  58
  59 /* Bit width of the SMT_ID (thread ID) field on the APIC ID
  60  */
  61 static inline unsigned apicid_smt_width(unsigned nr_cores, unsigned nr_threads)
  62 {
  63     return apicid_bitwidth_for_count(nr_threads);
  64 }
  65
  66 /* Bit width of the Core_ID field
  67  */
  68 static inline unsigned apicid_core_width(unsigned nr_cores, unsigned nr_threads)
  69 {
  70     return apicid_bitwidth_for_count(nr_cores);
  71 }
  72
  73 /* Bit offset of the Core_ID field
  74  */
  75 static inline unsigned apicid_core_offset(unsigned nr_cores,
  76                                           unsigned nr_threads)
  77 {
  78     return apicid_smt_width(nr_cores, nr_threads);
  79 }
  80
  81 /* Bit offset of the Pkg_ID (socket ID) field
  82  */
  83 static inline unsigned apicid_pkg_offset(unsigned nr_cores, unsigned nr_threads)
  84 {
  85     return apicid_core_offset(nr_cores, nr_threads) +
  86            apicid_core_width(nr_cores, nr_threads);
  87 }
  88
  89 /* Make APIC ID for the CPU based on Pkg_ID, Core_ID, SMT_ID
  90  *
  91  * The caller must make sure core_id < nr_cores and smt_id < nr_threads.
  92  */
  93 static inline apic_id_t apicid_from_topo_ids(unsigned nr_cores,
  94                                              unsigned nr_threads,
  95                                              unsigned pkg_id,
  96                                              unsigned core_id,
  97                                              unsigned smt_id)
  98 {
  99     return (pkg_id  << apicid_pkg_offset(nr_cores, nr_threads)) |
 100            (core_id << apicid_core_offset(nr_cores, nr_threads)) |
 101            smt_id;
 102 }
 103
 104 /* Calculate thread/core/package IDs for a specific topology,
 105  * based on (contiguous) CPU index
 106  */
 107 static inline void x86_topo_ids_from_idx(unsigned nr_cores,
 108                                          unsigned nr_threads,
 109                                          unsigned cpu_index,
 110                                          unsigned *pkg_id,
 111                                          unsigned *core_id,
 112                                          unsigned *smt_id)
 113 {
 114     unsigned core_index = cpu_index / nr_threads;
 115     *smt_id = cpu_index % nr_threads;
 116     *core_id = core_index % nr_cores;
 117     *pkg_id = core_index / nr_cores;
 118 }
 119
 120 /* Make APIC ID for the CPU 'cpu_index'
 121  *
 122  * 'cpu_index' is a sequential, contiguous ID for the CPU.
 123  */
 124 static inline apic_id_t x86_apicid_from_cpu_idx(unsigned nr_cores,
 125                                                 unsigned nr_threads,
 126                                                 unsigned cpu_index)
 127 {
 128     unsigned pkg_id, core_id, smt_id;
 129     x86_topo_ids_from_idx(nr_cores, nr_threads, cpu_index,
 130                           &pkg_id, &core_id, &smt_id);
 131     return apicid_from_topo_ids(nr_cores, nr_threads, pkg_id, core_id, smt_id);
 132 }
 133
 134 #endif /* HW_I386_TOPOLOGY_H */