arch/x86/kernel/cpu/mtrr/legacy.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2
   3 #include <linux/types.h>
   4 #include <linux/slab.h>
   5 #include <linux/syscore_ops.h>
   6 #include <asm/cpufeature.h>
   7 #include <asm/mtrr.h>
   8 #include <asm/processor.h>
   9 #include "mtrr.h"
  10
  11 void mtrr_set_if(void)
  12 {
  13         switch (boot_cpu_data.x86_vendor) {
  14         case X86_VENDOR_AMD:
  15                 /* Pre-Athlon (K6) AMD CPU MTRRs */
  16                 if (cpu_feature_enabled(X86_FEATURE_K6_MTRR))
  17                         mtrr_if = &amd_mtrr_ops;
  18                 break;
  19         case X86_VENDOR_CENTAUR:
  20                 if (cpu_feature_enabled(X86_FEATURE_CENTAUR_MCR))
  21                         mtrr_if = &centaur_mtrr_ops;
  22                 break;
  23         case X86_VENDOR_CYRIX:
  24                 if (cpu_feature_enabled(X86_FEATURE_CYRIX_ARR))
  25                         mtrr_if = &cyrix_mtrr_ops;
  26                 break;
  27         default:
  28                 break;
  29         }
  30 }
  31
  32 /*
  33  * The suspend/resume methods are only for CPUs without MTRR. CPUs using generic
  34  * MTRR driver don't require this.
  35  */
  36 struct mtrr_value {
  37         mtrr_type       ltype;
  38         unsigned long   lbase;
  39         unsigned long   lsize;
  40 };
  41
  42 static struct mtrr_value *mtrr_value;
  43
  44 static int mtrr_save(void)
  45 {
  46         int i;
  47
  48         if (!mtrr_value)
  49                 return -ENOMEM;
  50
  51         for (i = 0; i < num_var_ranges; i++) {
  52                 mtrr_if->get(i, &mtrr_value[i].lbase,
  53                                 &mtrr_value[i].lsize,
  54                                 &mtrr_value[i].ltype);
  55         }
  56         return 0;
  57 }
  58
  59 static void mtrr_restore(void)
  60 {
  61         int i;
  62
  63         for (i = 0; i < num_var_ranges; i++) {
  64                 if (mtrr_value[i].lsize) {
  65                         mtrr_if->set(i, mtrr_value[i].lbase,
  66                                      mtrr_value[i].lsize,
  67                                      mtrr_value[i].ltype);
  68                 }
  69         }
  70 }
  71
  72 static struct syscore_ops mtrr_syscore_ops = {
  73         .suspend        = mtrr_save,
  74         .resume         = mtrr_restore,
  75 };
  76
  77 void mtrr_register_syscore(void)
  78 {
  79         mtrr_value = kcalloc(num_var_ranges, sizeof(*mtrr_value), GFP_KERNEL);
  80
  81         /*
  82          * The CPU has no MTRR and seems to not support SMP. They have
  83          * specific drivers, we use a tricky method to support
  84          * suspend/resume for them.
  85          *
  86          * TBD: is there any system with such CPU which supports
  87          * suspend/resume? If no, we should remove the code.
  88          */
  89         register_syscore_ops(&mtrr_syscore_ops);
  90 }