Merge branch 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull EFI fixes from Ingo Molnar:
 "Two EFI boot fixes, one for arm64 and one for x86 systems with certain
  firmware versions"

* 'efi-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  efi/fdt: Avoid FDT manipulation after ExitBootServices()
  x86/efi: Always map the first physical page into the EFI pagetables

2 files changed, 19 insertions, 11 deletions

diff --git a/arch/x86/platform/efi/efi_64.c b/arch/x86/platform/efi/efi_64.c
index 319148bd4b05..2f25a363068c 100644
--- a/arch/x86/platform/efi/efi_64.c
+++ b/arch/x86/platform/efi/efi_64.c
@@ -269,6 +269,22 @@ int __init efi_setup_page_tables(unsigned long pa_memmap, unsigned num_pages)
         efi_scratch.use_pgd = true;
 
         /*
+         * Certain firmware versions are way too sentimential and still believe
+         * they are exclusive and unquestionable owners of the first physical page,
+         * even though they explicitly mark it as EFI_CONVENTIONAL_MEMORY
+         * (but then write-access it later during SetVirtualAddressMap()).
+         *
+         * Create a 1:1 mapping for this page, to avoid triple faults during early
+         * boot with such firmware. We are free to hand this page to the BIOS,
+         * as trim_bios_range() will reserve the first page and isolate it away
+         * from memory allocators anyway.
+         */
+        if (kernel_map_pages_in_pgd(pgd, 0x0, 0x0, 1, _PAGE_RW)) {
+                pr_err("Failed to create 1:1 mapping for the first page!\n");
+                return 1;
+        }
+
+        /*
          * When making calls to the firmware everything needs to be 1:1
          * mapped and addressable with 32-bit pointers. Map the kernel
          * text and allocate a new stack because we can't rely on the
diff --git a/drivers/firmware/efi/libstub/fdt.c b/drivers/firmware/efi/libstub/fdt.c
index 921dfa047202..260c4b4b492e 100644
--- a/drivers/firmware/efi/libstub/fdt.c
+++ b/drivers/firmware/efi/libstub/fdt.c
@@ -187,6 +187,7 @@ static efi_status_t update_fdt_memmap(void *fdt, struct efi_boot_memmap *map)
 struct exit_boot_struct {
         efi_memory_desc_t *runtime_map;
         int *runtime_entry_count;
+        void *new_fdt_addr;
 };
 
 static efi_status_t exit_boot_func(efi_system_table_t *sys_table_arg,
@@ -202,7 +203,7 @@ static efi_status_t exit_boot_func(efi_system_table_t *sys_table_arg,
         efi_get_virtmap(*map->map, *map->map_size, *map->desc_size,
                         p->runtime_map, p->runtime_entry_count);
 
-        return EFI_SUCCESS;
+        return update_fdt_memmap(p->new_fdt_addr, map);
 }
 
 /*
@@ -300,22 +301,13 @@ efi_status_t allocate_new_fdt_and_exit_boot(efi_system_table_t *sys_table,
 
         priv.runtime_map = runtime_map;
         priv.runtime_entry_count = &runtime_entry_count;
+        priv.new_fdt_addr = (void *)*new_fdt_addr;
         status = efi_exit_boot_services(sys_table, handle, &map, &priv,
                                         exit_boot_func);
 
         if (status == EFI_SUCCESS) {
                 efi_set_virtual_address_map_t *svam;
 
-                status = update_fdt_memmap((void *)*new_fdt_addr, &map);
-                if (status != EFI_SUCCESS) {
-                        /*
-                         * The kernel won't get far without the memory map, but
-                         * may still be able to print something meaningful so
-                         * return success here.
-                         */
-                        return EFI_SUCCESS;
-                }
-
                 /* Install the new virtual address map */
                 svam = sys_table->runtime->set_virtual_address_map;
                 status = svam(runtime_entry_count * desc_size, desc_size,