From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Patrick Steinhardt <ps@pks.im>
Date: Thu, 21 Apr 2022 15:24:22 +1000
Subject: [PATCH] kern/efi/mm: Implement runtime addition of pages

Adjust the interface of grub_efi_mm_add_regions() to take a set of
GRUB_MM_ADD_REGION_* flags, which most notably is currently only the
GRUB_MM_ADD_REGION_CONSECUTIVE 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>
Signed-off-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
Tested-by: Patrick Steinhardt <ps@pks.im>
(cherry picked from commit 1df2934822df4c1170dde069d97cfbf7a9572bba)
---
 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 e0ebc65dba..016ba6cf2f 100644
--- a/grub-core/kern/efi/mm.c
+++ b/grub-core/kern/efi/mm.c
@@ -518,7 +518,8 @@ static grub_err_t
 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,
+		    unsigned int flags)
 {
   grub_efi_memory_descriptor_t *desc;
 
@@ -532,6 +533,10 @@ add_memory_regions (grub_efi_memory_descriptor_t *memory_map,
 
       start = desc->physical_start;
       pages = desc->num_pages;
+
+      if (pages < required_pages && (flags & GRUB_MM_ADD_REGION_CONSECUTIVE))
+	continue;
+
       if (pages > required_pages)
 	{
 	  start += PAGES_TO_BYTES (pages - required_pages);
@@ -672,7 +677,7 @@ grub_nx_init (void)
 }
 
 static grub_err_t
-grub_efi_mm_add_regions (grub_size_t required_bytes)
+grub_efi_mm_add_regions (grub_size_t required_bytes, unsigned int flags)
 {
   grub_efi_memory_descriptor_t *memory_map;
   grub_efi_memory_descriptor_t *memory_map_end;
@@ -729,7 +734,8 @@ grub_efi_mm_add_regions (grub_size_t required_bytes)
   /* Allocate memory regions for GRUB's memory management.  */
   err = add_memory_regions (filtered_memory_map, desc_size,
 			    filtered_memory_map_end,
-			    BYTES_TO_PAGES (required_bytes));
+			    BYTES_TO_PAGES (required_bytes),
+			    flags);
   if (err != GRUB_ERR_NONE)
     return err;
 
@@ -756,8 +762,9 @@ grub_efi_mm_add_regions (grub_size_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, GRUB_MM_ADD_REGION_NONE) != GRUB_ERR_NONE)
     grub_fatal ("%s", grub_errmsg);
+  grub_mm_add_region_fn = grub_efi_mm_add_regions;
 }
 
 #if defined (__aarch64__) || defined (__arm__) || defined (__riscv)