root/arch/x86/kernel/acpi/cstate.c

DEFINITIONS

1. acpi_processor_power_init_bm_check
2. acpi_processor_ffh_cstate_probe_cpu
3. acpi_processor_ffh_cstate_probe
4. acpi_processor_ffh_cstate_enter
5. ffh_cstate_init
6. ffh_cstate_exit

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2005 Intel Corporation
   4  *      Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
   5  *      - Added _PDC for SMP C-states on Intel CPUs
   6  */
   7 
   8 #include <linux/kernel.h>
   9 #include <linux/export.h>
  10 #include <linux/init.h>
  11 #include <linux/acpi.h>
  12 #include <linux/cpu.h>
  13 #include <linux/sched.h>
  14 
  15 #include <acpi/processor.h>
  16 #include <asm/mwait.h>
  17 #include <asm/special_insns.h>
  18 
  19 /*
  20  * Initialize bm_flags based on the CPU cache properties
  21  * On SMP it depends on cache configuration
  22  * - When cache is not shared among all CPUs, we flush cache
  23  *   before entering C3.
  24  * - When cache is shared among all CPUs, we use bm_check
  25  *   mechanism as in UP case
  26  *
  27  * This routine is called only after all the CPUs are online
  28  */
  29 void acpi_processor_power_init_bm_check(struct acpi_processor_flags *flags,
  30                                         unsigned int cpu)
  31 {
  32         struct cpuinfo_x86 *c = &cpu_data(cpu);
  33 
  34         flags->bm_check = 0;
  35         if (num_online_cpus() == 1)
  36                 flags->bm_check = 1;
  37         else if (c->x86_vendor == X86_VENDOR_INTEL) {
  38                 /*
  39                  * Today all MP CPUs that support C3 share cache.
  40                  * And caches should not be flushed by software while
  41                  * entering C3 type state.
  42                  */
  43                 flags->bm_check = 1;
  44         }
  45 
  46         /*
  47          * On all recent Intel platforms, ARB_DISABLE is a nop.
  48          * So, set bm_control to zero to indicate that ARB_DISABLE
  49          * is not required while entering C3 type state on
  50          * P4, Core and beyond CPUs
  51          */
  52         if (c->x86_vendor == X86_VENDOR_INTEL &&
  53             (c->x86 > 0xf || (c->x86 == 6 && c->x86_model >= 0x0f)))
  54                         flags->bm_control = 0;
  55         /*
  56          * For all recent Centaur CPUs, the ucode will make sure that each
  57          * core can keep cache coherence with each other while entering C3
  58          * type state. So, set bm_check to 1 to indicate that the kernel
  59          * doesn't need to execute a cache flush operation (WBINVD) when
  60          * entering C3 type state.
  61          */
  62         if (c->x86_vendor == X86_VENDOR_CENTAUR) {
  63                 if (c->x86 > 6 || (c->x86 == 6 && c->x86_model == 0x0f &&
  64                     c->x86_stepping >= 0x0e))
  65                         flags->bm_check = 1;
  66         }
  67 
  68         if (c->x86_vendor == X86_VENDOR_ZHAOXIN) {
  69                 /*
  70                  * All Zhaoxin CPUs that support C3 share cache.
  71                  * And caches should not be flushed by software while
  72                  * entering C3 type state.
  73                  */
  74                 flags->bm_check = 1;
  75                 /*
  76                  * On all recent Zhaoxin platforms, ARB_DISABLE is a nop.
  77                  * So, set bm_control to zero to indicate that ARB_DISABLE
  78                  * is not required while entering C3 type state.
  79                  */
  80                 flags->bm_control = 0;
  81         }
  82 }
  83 EXPORT_SYMBOL(acpi_processor_power_init_bm_check);
  84 
  85 /* The code below handles cstate entry with monitor-mwait pair on Intel*/
  86 
  87 struct cstate_entry {
  88         struct {
  89                 unsigned int eax;
  90                 unsigned int ecx;
  91         } states[ACPI_PROCESSOR_MAX_POWER];
  92 };
  93 static struct cstate_entry __percpu *cpu_cstate_entry;  /* per CPU ptr */
  94 
  95 static short mwait_supported[ACPI_PROCESSOR_MAX_POWER];
  96 
  97 #define NATIVE_CSTATE_BEYOND_HALT       (2)
  98 
  99 static long acpi_processor_ffh_cstate_probe_cpu(void *_cx)
 100 {
 101         struct acpi_processor_cx *cx = _cx;
 102         long retval;
 103         unsigned int eax, ebx, ecx, edx;
 104         unsigned int edx_part;
 105         unsigned int cstate_type; /* C-state type and not ACPI C-state type */
 106         unsigned int num_cstate_subtype;
 107 
 108         cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
 109 
 110         /* Check whether this particular cx_type (in CST) is supported or not */
 111         cstate_type = ((cx->address >> MWAIT_SUBSTATE_SIZE) &
 112                         MWAIT_CSTATE_MASK) + 1;
 113         edx_part = edx >> (cstate_type * MWAIT_SUBSTATE_SIZE);
 114         num_cstate_subtype = edx_part & MWAIT_SUBSTATE_MASK;
 115 
 116         retval = 0;
 117         /* If the HW does not support any sub-states in this C-state */
 118         if (num_cstate_subtype == 0) {
 119                 pr_warn(FW_BUG "ACPI MWAIT C-state 0x%x not supported by HW (0x%x)\n",
 120                                 cx->address, edx_part);
 121                 retval = -1;
 122                 goto out;
 123         }
 124 
 125         /* mwait ecx extensions INTERRUPT_BREAK should be supported for C2/C3 */
 126         if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
 127             !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) {
 128                 retval = -1;
 129                 goto out;
 130         }
 131 
 132         if (!mwait_supported[cstate_type]) {
 133                 mwait_supported[cstate_type] = 1;
 134                 printk(KERN_DEBUG
 135                         "Monitor-Mwait will be used to enter C-%d state\n",
 136                         cx->type);
 137         }
 138         snprintf(cx->desc,
 139                         ACPI_CX_DESC_LEN, "ACPI FFH MWAIT 0x%x",
 140                         cx->address);
 141 out:
 142         return retval;
 143 }
 144 
 145 int acpi_processor_ffh_cstate_probe(unsigned int cpu,
 146                 struct acpi_processor_cx *cx, struct acpi_power_register *reg)
 147 {
 148         struct cstate_entry *percpu_entry;
 149         struct cpuinfo_x86 *c = &cpu_data(cpu);
 150         long retval;
 151 
 152         if (!cpu_cstate_entry || c->cpuid_level < CPUID_MWAIT_LEAF)
 153                 return -1;
 154 
 155         if (reg->bit_offset != NATIVE_CSTATE_BEYOND_HALT)
 156                 return -1;
 157 
 158         percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
 159         percpu_entry->states[cx->index].eax = 0;
 160         percpu_entry->states[cx->index].ecx = 0;
 161 
 162         /* Make sure we are running on right CPU */
 163 
 164         retval = call_on_cpu(cpu, acpi_processor_ffh_cstate_probe_cpu, cx,
 165                              false);
 166         if (retval == 0) {
 167                 /* Use the hint in CST */
 168                 percpu_entry->states[cx->index].eax = cx->address;
 169                 percpu_entry->states[cx->index].ecx = MWAIT_ECX_INTERRUPT_BREAK;
 170         }
 171 
 172         /*
 173          * For _CST FFH on Intel, if GAS.access_size bit 1 is cleared,
 174          * then we should skip checking BM_STS for this C-state.
 175          * ref: "Intel Processor Vendor-Specific ACPI Interface Specification"
 176          */
 177         if ((c->x86_vendor == X86_VENDOR_INTEL) && !(reg->access_size & 0x2))
 178                 cx->bm_sts_skip = 1;
 179 
 180         return retval;
 181 }
 182 EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_probe);
 183 
 184 void __cpuidle acpi_processor_ffh_cstate_enter(struct acpi_processor_cx *cx)
 185 {
 186         unsigned int cpu = smp_processor_id();
 187         struct cstate_entry *percpu_entry;
 188 
 189         percpu_entry = per_cpu_ptr(cpu_cstate_entry, cpu);
 190         mwait_idle_with_hints(percpu_entry->states[cx->index].eax,
 191                               percpu_entry->states[cx->index].ecx);
 192 }
 193 EXPORT_SYMBOL_GPL(acpi_processor_ffh_cstate_enter);
 194 
 195 static int __init ffh_cstate_init(void)
 196 {
 197         struct cpuinfo_x86 *c = &boot_cpu_data;
 198 
 199         if (c->x86_vendor != X86_VENDOR_INTEL &&
 200             c->x86_vendor != X86_VENDOR_AMD)
 201                 return -1;
 202 
 203         cpu_cstate_entry = alloc_percpu(struct cstate_entry);
 204         return 0;
 205 }
 206 
 207 static void __exit ffh_cstate_exit(void)
 208 {
 209         free_percpu(cpu_cstate_entry);
 210         cpu_cstate_entry = NULL;
 211 }
 212 
 213 arch_initcall(ffh_cstate_init);
 214 __exitcall(ffh_cstate_exit);