x86, efi: Do not reserve boot services regions within reserved areas

Commit 916f676f8dc started reserving boot service code since some systems
require you to keep that code around until SetVirtualAddressMap is called.

However, in some cases those areas will overlap with reserved regions.
The proper medium-term fix is to fix the bootloader to prevent the
conflicts from occurring by moving the kernel to a better position,
but the kernel should check for this possibility, and only reserve regions
which can be reserved.

Signed-off-by: Maarten Lankhorst <m.b.lankhorst@gmail.com>
Link: http://lkml.kernel.org/r/4DF7A005.1050407@gmail.com
Acked-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 25 insertions, 4 deletions

diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index 0d3a4fa34560..474356b98ede 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -310,14 +310,31 @@ void __init efi_reserve_boot_services(void)
 
         for (p = memmap.map; p < memmap.map_end; p += memmap.desc_size) {
                 efi_memory_desc_t *md = p;
-                unsigned long long start = md->phys_addr;
-                unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
+                u64 start = md->phys_addr;
+                u64 size = md->num_pages << EFI_PAGE_SHIFT;
 
                 if (md->type != EFI_BOOT_SERVICES_CODE &&
                     md->type != EFI_BOOT_SERVICES_DATA)
                         continue;
-
-                memblock_x86_reserve_range(start, start + size, "EFI Boot");
+                /* Only reserve where possible:
+                 * - Not within any already allocated areas
+                 * - Not over any memory area (really needed, if above?)
+                 * - Not within any part of the kernel
+                 * - Not the bios reserved area
+                */
+                if ((start+size >= virt_to_phys(_text)
+                                && start <= virt_to_phys(_end)) ||
+                        !e820_all_mapped(start, start+size, E820_RAM) ||
+                        memblock_x86_check_reserved_size(&start, &size,
+                                                        1<<EFI_PAGE_SHIFT)) {
+                        /* Could not reserve, skip it */
+                        md->num_pages = 0;
+                        memblock_dbg(PFX "Could not reserve boot range "
+                                        "[0x%010llx-0x%010llx]\n",
+                                                start, start+size-1);
+                } else
+                        memblock_x86_reserve_range(start, start+size,
+                                                        "EFI Boot");
         }
 }
 
@@ -334,6 +351,10 @@ static void __init efi_free_boot_services(void)
                     md->type != EFI_BOOT_SERVICES_DATA)
                         continue;
 
+                /* Could not reserve boot area */
+                if (!size)
+                        continue;
+
                 free_bootmem_late(start, size);
         }
 }