src/cpu/x86/backup_default_smm.c

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 #include <acpi/acpi.h>
   4 #include <cbmem.h>
   5 #include <console/console.h>
   6 #include <cpu/x86/smm.h>
   7 #include <string.h>
   8
   9 void *backup_default_smm_area(void)
  10 {
  11         void *save_area;
  12         const void *default_smm = (void *)SMM_DEFAULT_BASE;
  13
  14         if (!CONFIG(HAVE_ACPI_RESUME))
  15                 return NULL;
  16
  17         /*
  18          * The buffer needs to be preallocated regardless. In the non-resume
  19          * path it will be allocated for handling resume. Note that cbmem_add()
  20          * does a find before the addition.
  21          */
  22         save_area = cbmem_add(CBMEM_ID_SMM_SAVE_SPACE, SMM_DEFAULT_SIZE);
  23
  24         if (save_area == NULL) {
  25                 printk(BIOS_DEBUG, "SMM save area not added.\n");
  26                 return NULL;
  27         }
  28
  29         /* Only back up the area on S3 resume. */
  30         if (acpi_is_wakeup_s3()) {
  31                 memcpy(save_area, default_smm, SMM_DEFAULT_SIZE);
  32                 return save_area;
  33         }
  34
  35         /*
  36          * Not the S3 resume path. No need to restore memory contents after
  37          * SMM relocation.
  38          */
  39         return NULL;
  40 }
  41
  42 void restore_default_smm_area(void *smm_save_area)
  43 {
  44         void *default_smm = (void *)SMM_DEFAULT_BASE;
  45
  46         if (smm_save_area == NULL)
  47                 return;
  48
  49         memcpy(default_smm, smm_save_area, SMM_DEFAULT_SIZE);
  50 }