[RFC PATCH 3/3] efi: mm: implement runtime addition of pages

[Patrick Steinhardt]

Adjust the interface of `grub_efi_mm_add_regions ()` to take a set of
`GRUB_MM_REGION_*` flags, which most notably is currently only the
`CONSECUTVE` flag. This allows us to set the function up as callback for
the memory subsystem and have it call out to us in case there's not
enough pages available in the current heap.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 grub-core/kern/efi/mm.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/grub-core/kern/efi/mm.c b/grub-core/kern/efi/mm.c
index 76f0f6a0f..092097355 100644
--- a/grub-core/kern/efi/mm.c
+++ b/grub-core/kern/efi/mm.c
@@ -468,7 +468,8 @@ static void
 add_memory_regions (grub_efi_memory_descriptor_t *memory_map,
                    grub_efi_uintn_t desc_size,
                    grub_efi_memory_descriptor_t *memory_map_end,
-                   grub_efi_uint64_t required_pages)
+                   grub_efi_uint64_t required_pages,
+                   char consecutive)
 {
   grub_efi_memory_descriptor_t *desc;
 
@@ -482,6 +483,10 @@ add_memory_regions (grub_efi_memory_descriptor_t 
*memory_map,
 
       start = desc->physical_start;
       pages = desc->num_pages;
+
+      if (pages < required_pages && consecutive)
+       continue;
+
       if (pages > required_pages)
        {
          start += PAGES_TO_BYTES (pages - required_pages);
@@ -543,7 +548,7 @@ print_memory_map (grub_efi_memory_descriptor_t *memory_map,
 #endif
 
 static grub_err_t
-grub_efi_mm_add_regions (grub_efi_uint64_t required_bytes)
+grub_efi_mm_add_regions (grub_efi_uint64_t required_bytes, unsigned flags)
 {
   grub_efi_memory_descriptor_t *memory_map;
   grub_efi_memory_descriptor_t *memory_map_end;
@@ -597,7 +602,8 @@ grub_efi_mm_add_regions (grub_efi_uint64_t required_bytes)
   /* Allocate memory regions for GRUB's memory management.  */
   add_memory_regions (filtered_memory_map, desc_size,
                      filtered_memory_map_end,
-                     BYTES_TO_PAGES (required_bytes));
+                     BYTES_TO_PAGES (required_bytes),
+                     flags & GRUB_MM_REGION_CONSECUTIVE);
 
 #if 0
   /* For debug.  */
@@ -622,8 +628,9 @@ grub_efi_mm_add_regions (grub_efi_uint64_t required_bytes)
 void
 grub_efi_mm_init (void)
 {
-  if (grub_efi_mm_add_regions (DEFAULT_HEAP_SIZE) != GRUB_ERR_NONE)
+  if (grub_efi_mm_add_regions (DEFAULT_HEAP_SIZE, 0) != GRUB_ERR_NONE)
     grub_fatal (grub_errmsg);
+  grub_mm_region_fn = grub_efi_mm_add_regions;
 }
 
 #if defined (__aarch64__) || defined (__arm__) || defined (__riscv)
-- 
2.26.2

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