drivers/firmware/efi/x86_fake_mem.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright(c) 2019 Intel Corporation. All rights reserved. */
   3 #include <linux/efi.h>
   4 #include <asm/e820/api.h>
   5 #include "fake_mem.h"
   6
   7 void __init efi_fake_memmap_early(void)
   8 {
   9         int i;
  10
  11         /*
  12          * The late efi_fake_mem() call can handle all requests if
  13          * EFI_MEMORY_SP support is disabled.
  14          */
  15         if (!efi_soft_reserve_enabled())
  16                 return;
  17
  18         if (!efi_enabled(EFI_MEMMAP) || !nr_fake_mem)
  19                 return;
  20
  21         /*
  22          * Given that efi_fake_memmap() needs to perform memblock
  23          * allocations it needs to run after e820__memblock_setup().
  24          * However, if efi_fake_mem specifies EFI_MEMORY_SP for a given
  25          * address range that potentially needs to mark the memory as
  26          * reserved prior to e820__memblock_setup(). Update e820
  27          * directly if EFI_MEMORY_SP is specified for an
  28          * EFI_CONVENTIONAL_MEMORY descriptor.
  29          */
  30         for (i = 0; i < nr_fake_mem; i++) {
  31                 struct efi_mem_range *mem = &efi_fake_mems[i];
  32                 efi_memory_desc_t *md;
  33                 u64 m_start, m_end;
  34
  35                 if ((mem->attribute & EFI_MEMORY_SP) == 0)
  36                         continue;
  37
  38                 m_start = mem->range.start;
  39                 m_end = mem->range.end;
  40                 for_each_efi_memory_desc(md) {
  41                         u64 start, end, size;
  42
  43                         if (md->type != EFI_CONVENTIONAL_MEMORY)
  44                                 continue;
  45
  46                         start = md->phys_addr;
  47                         end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1;
  48
  49                         if (m_start <= end && m_end >= start)
  50                                 /* fake range overlaps descriptor */;
  51                         else
  52                                 continue;
  53
  54                         /*
  55                          * Trim the boundary of the e820 update to the
  56                          * descriptor in case the fake range overlaps
  57                          * !EFI_CONVENTIONAL_MEMORY
  58                          */
  59                         start = max(start, m_start);
  60                         end = min(end, m_end);
  61                         size = end - start + 1;
  62
  63                         if (end <= start)
  64                                 continue;
  65
  66                         /*
  67                          * Ensure each efi_fake_mem instance results in
  68                          * a unique e820 resource
  69                          */
  70                         e820__range_remove(start, size, E820_TYPE_RAM, 1);
  71                         e820__range_add(start, size, E820_TYPE_SOFT_RESERVED);
  72                         e820__update_table(e820_table);
  73                 }
  74         }
  75 }