X-Git-Url: https://git.proxmox.com/?a=blobdiff_plain;f=arch%2Fx86%2Fplatform%2Fefi%2Fefi_64.c;h=2f25a363068cf9723e8b418e8c1942a6d3ca4029;hb=bf29bddf0417a4783da3b24e8c9e017ac649326f;hp=319148bd4b05091d24576a7535b10aad7bec0c2d;hpb=f4000cd99750065d5177555c0a805c97174d1b9f;p=mirror_ubuntu-artful-kernel.git

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
@@ -268,6 +268,22 @@ 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