From 816e76129ed5fadd28e526c43397c79775194b5c Mon Sep 17 00:00:00 2001 From: Matt Fleming Date: Mon, 29 Feb 2016 21:22:52 +0000 Subject: efi: Allow drivers to reserve boot services forever Today, it is not possible for drivers to reserve EFI boot services for access after efi_free_boot_services() has been called on x86. For ARM/arm64 it can be done simply by calling memblock_reserve(). Having this ability for all three architectures is desirable for a couple of reasons, 1) It saves drivers copying data out of those regions 2) kexec reboot can now make use of things like ESRT Instead of using the standard memblock_reserve() which is insufficient to reserve the region on x86 (see efi_reserve_boot_services()), a new API is introduced in this patch; efi_mem_reserve(). efi.memmap now always represents which EFI memory regions are available. On x86 the EFI boot services regions that have not been reserved via efi_mem_reserve() will be removed from efi.memmap during efi_free_boot_services(). This has implications for kexec, since it is not possible for a newly kexec'd kernel to access the same boot services regions that the initial boot kernel had access to unless they are reserved by every kexec kernel in the chain. Tested-by: Dave Young [kexec/kdump] Tested-by: Ard Biesheuvel [arm] Acked-by: Ard Biesheuvel Cc: Leif Lindholm Cc: Peter Jones Cc: Borislav Petkov Cc: Mark Rutland Signed-off-by: Matt Fleming --- include/linux/efi.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/efi.h') diff --git a/include/linux/efi.h b/include/linux/efi.h index 987c18f6fcae..3fe4f3c47834 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -944,6 +944,7 @@ extern u64 efi_mem_attribute (unsigned long phys_addr, unsigned long size); extern int __init efi_uart_console_only (void); extern u64 efi_mem_desc_end(efi_memory_desc_t *md); extern int efi_mem_desc_lookup(u64 phys_addr, efi_memory_desc_t *out_md); +extern void efi_mem_reserve(phys_addr_t addr, u64 size); extern void efi_initialize_iomem_resources(struct resource *code_resource, struct resource *data_resource, struct resource *bss_resource); extern void efi_reserve_boot_services(void); -- cgit v1.2.3