From patchwork Mon Aug 7 16:27:20 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ard Biesheuvel X-Patchwork-Id: 711354 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5CEA7C00528 for ; Mon, 7 Aug 2023 16:29:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229965AbjHGQ3r (ORCPT ); Mon, 7 Aug 2023 12:29:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34676 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231635AbjHGQ3V (ORCPT ); Mon, 7 Aug 2023 12:29:21 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C8DE02123; Mon, 7 Aug 2023 09:28:30 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8E9D661F2A; Mon, 7 Aug 2023 16:28:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6B729C433C7; Mon, 7 Aug 2023 16:28:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1691425709; bh=4BrEDeMcw87j3NkeaQlb25oenN9ZYfFjYJJ/OMIhV6Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S2hypmOSMFRuHXjH7RY4hrzoTPL28/mBnVZQfn5/Gj7LkDHJ07Jp5Fq9DrD923rll KpLai52e5snFeA3pnsbACEId0Q/zJnnG64/t3cZVWUI8y4lAqUtkTjFFqrcuhhkY4V R7VPb5fBnUrctflFDRkjcKx5SPsdWiMDMePKKdpt8rBkdKBq4ZqeEZH9NcXf3OrJT3 zmXDzIAUw94ZEBEntjkNLQ8po5ngkBEt7DLX+1wuNblSRpYBmBzzLCPFZP3WDukePI /biRrPpKnbADumvMM8IoFhEUuIeZlaH6pzRVebLtr/7B8XvXDU0lTWFDlPVy28W2gG DbV9OEA8Q9zlA== From: Ard Biesheuvel To: linux-efi@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Ard Biesheuvel , Borislav Petkov , Dave Hansen , Ingo Molnar , Thomas Gleixner Subject: [PATCH v9 23/23] x86/efistub: Avoid legacy decompressor when doing EFI boot Date: Mon, 7 Aug 2023 18:27:20 +0200 Message-Id: <20230807162720.545787-24-ardb@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230807162720.545787-1-ardb@kernel.org> References: <20230807162720.545787-1-ardb@kernel.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=19415; i=ardb@kernel.org; h=from:subject; bh=4BrEDeMcw87j3NkeaQlb25oenN9ZYfFjYJJ/OMIhV6Y=; b=owGbwMvMwCFmkMcZplerG8N4Wi2JIeWidIbEiTSV7NVle7LaWk6udzvEGeE5a/PTYol+1nOz/ 7JG/1XtKGVhEONgkBVTZBGY/ffdztMTpWqdZ8nCzGFlAhnCwMUpABPx4WBk+HvzR4jU5387Zm9k 1zMtSKq5W8Z6+M//xQWf49mPsE7t8WD4H2nfuZ7t9Jrjr65N358TrrTIeYNnzNNHr9IsRUX1prB 7MgEA X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org The bare metal decompressor code was never really intended to run in a hosted environment such as the EFI boot services, and does a few things that are becoming problematic in the context of EFI boot now that the logo requirements are getting tighter: EFI executables will no longer be allowed to consist of a single executable section that is mapped with read, write and execute permissions if they are intended for use in a context where Secure Boot is enabled (and where Microsoft's set of certificates is used, i.e., every x86 PC built to run Windows) To avoid stepping on reserved memory before having inspected the E820 tables, and to ensure the correct placement when running a kernel build that is non-relocatable, the bare metal decompressor moves its own executable image to the end of the allocation that was reserved for it, in order to perform the decompression in place. This means the region in question requires both write and execute permissions, which either need to be given upfront (which EFI will no longer permit), or need to be applied on demand using the existing page fault handling framework. However, the physical placement of the kernel is usually randomized anyway, and even if it isn't, a dedicated decompression output buffer can be allocated anywhere in memory using EFI APIs when still running in the boot services, given that EFI support already implies a relocatable kernel. This means that decompression in place is never necessary, nor is moving the compressed image from one end to the other. Since EFI already maps all of memory 1:1, it is also unnecessary to create new page tables or handle page faults when decompressing the kernel. That means there is also no need to replace the special exception handlers for SEV. Generally, there is little need to do any of the things that the decompressor does beyond - initialize SEV encryption, if needed, - perform the 4/5 level paging switch, if needed, - decompress the kernel - relocate the kernel So do all of this from the EFI stub code, and avoid the bare metal decompressor altogether. Signed-off-by: Ard Biesheuvel --- arch/x86/boot/compressed/Makefile | 5 + arch/x86/boot/compressed/efi_mixed.S | 55 ------- arch/x86/boot/compressed/head_32.S | 13 -- arch/x86/boot/compressed/head_64.S | 27 ---- arch/x86/include/asm/efi.h | 7 +- arch/x86/include/asm/sev.h | 2 + drivers/firmware/efi/libstub/x86-stub.c | 166 +++++++++----------- 7 files changed, 84 insertions(+), 191 deletions(-) diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 40d2ff503079e594..71fc531b95b4eede 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -74,6 +74,11 @@ LDFLAGS_vmlinux += -z noexecstack ifeq ($(CONFIG_LD_IS_BFD),y) LDFLAGS_vmlinux += $(call ld-option,--no-warn-rwx-segments) endif +ifeq ($(CONFIG_EFI_STUB),y) +# ensure that the static EFI stub library will be pulled in, even if it is +# never referenced explicitly from the startup code +LDFLAGS_vmlinux += -u efi_pe_entry +endif LDFLAGS_vmlinux += -T hostprogs := mkpiggy diff --git a/arch/x86/boot/compressed/efi_mixed.S b/arch/x86/boot/compressed/efi_mixed.S index 8a02a151806df14c..f4e22ef774ab6b4a 100644 --- a/arch/x86/boot/compressed/efi_mixed.S +++ b/arch/x86/boot/compressed/efi_mixed.S @@ -269,10 +269,6 @@ SYM_FUNC_START_LOCAL(efi32_entry) jmp startup_32 SYM_FUNC_END(efi32_entry) -#define ST32_boottime 60 // offsetof(efi_system_table_32_t, boottime) -#define BS32_handle_protocol 88 // offsetof(efi_boot_services_32_t, handle_protocol) -#define LI32_image_base 32 // offsetof(efi_loaded_image_32_t, image_base) - /* * efi_status_t efi32_pe_entry(efi_handle_t image_handle, * efi_system_table_32_t *sys_table) @@ -280,8 +276,6 @@ SYM_FUNC_END(efi32_entry) SYM_FUNC_START(efi32_pe_entry) pushl %ebp movl %esp, %ebp - pushl %eax // dummy push to allocate loaded_image - pushl %ebx // save callee-save registers pushl %edi @@ -290,48 +284,8 @@ SYM_FUNC_START(efi32_pe_entry) movl $0x80000003, %eax // EFI_UNSUPPORTED jnz 2f - call 1f -1: pop %ebx - - /* Get the loaded image protocol pointer from the image handle */ - leal -4(%ebp), %eax - pushl %eax // &loaded_image - leal (loaded_image_proto - 1b)(%ebx), %eax - pushl %eax // pass the GUID address - pushl 8(%ebp) // pass the image handle - - /* - * Note the alignment of the stack frame. - * sys_table - * handle <-- 16-byte aligned on entry by ABI - * return address - * frame pointer - * loaded_image <-- local variable - * saved %ebx <-- 16-byte aligned here - * saved %edi - * &loaded_image - * &loaded_image_proto - * handle <-- 16-byte aligned for call to handle_protocol - */ - - movl 12(%ebp), %eax // sys_table - movl ST32_boottime(%eax), %eax // sys_table->boottime - call *BS32_handle_protocol(%eax) // sys_table->boottime->handle_protocol - addl $12, %esp // restore argument space - testl %eax, %eax - jnz 2f - movl 8(%ebp), %ecx // image_handle movl 12(%ebp), %edx // sys_table - movl -4(%ebp), %esi // loaded_image - movl LI32_image_base(%esi), %esi // loaded_image->image_base - leal (startup_32 - 1b)(%ebx), %ebp // runtime address of startup_32 - /* - * We need to set the image_offset variable here since startup_32() will - * use it before we get to the 64-bit efi_pe_entry() in C code. - */ - subl %esi, %ebp // calculate image_offset - movl %ebp, (image_offset - 1b)(%ebx) // save image_offset xorl %esi, %esi jmp efi32_entry // pass %ecx, %edx, %esi // no other registers remain live @@ -350,15 +304,6 @@ SYM_FUNC_START_NOALIGN(efi64_stub_entry) SYM_FUNC_END(efi64_stub_entry) #endif - .section ".rodata" - /* EFI loaded image protocol GUID */ - .balign 4 -SYM_DATA_START_LOCAL(loaded_image_proto) - .long 0x5b1b31a1 - .word 0x9562, 0x11d2 - .byte 0x8e, 0x3f, 0x00, 0xa0, 0xc9, 0x69, 0x72, 0x3b -SYM_DATA_END(loaded_image_proto) - .data .balign 8 SYM_DATA_START_LOCAL(efi32_boot_gdt) diff --git a/arch/x86/boot/compressed/head_32.S b/arch/x86/boot/compressed/head_32.S index 3af4a383615b3e1f..1cfe9802a42fe570 100644 --- a/arch/x86/boot/compressed/head_32.S +++ b/arch/x86/boot/compressed/head_32.S @@ -84,19 +84,6 @@ SYM_FUNC_START(startup_32) #ifdef CONFIG_RELOCATABLE leal startup_32@GOTOFF(%edx), %ebx - -#ifdef CONFIG_EFI_STUB -/* - * If we were loaded via the EFI LoadImage service, startup_32() will be at an - * offset to the start of the space allocated for the image. efi_pe_entry() will - * set up image_offset to tell us where the image actually starts, so that we - * can use the full available buffer. - * image_offset = startup_32 - image_base - * Otherwise image_offset will be zero and has no effect on the calculations. - */ - subl image_offset@GOTOFF(%edx), %ebx -#endif - movl BP_kernel_alignment(%esi), %eax decl %eax addl %eax, %ebx diff --git a/arch/x86/boot/compressed/head_64.S b/arch/x86/boot/compressed/head_64.S index 28f46051c706724e..bf4a10a5794f1c84 100644 --- a/arch/x86/boot/compressed/head_64.S +++ b/arch/x86/boot/compressed/head_64.S @@ -146,19 +146,6 @@ SYM_FUNC_START(startup_32) #ifdef CONFIG_RELOCATABLE movl %ebp, %ebx - -#ifdef CONFIG_EFI_STUB -/* - * If we were loaded via the EFI LoadImage service, startup_32 will be at an - * offset to the start of the space allocated for the image. efi_pe_entry will - * set up image_offset to tell us where the image actually starts, so that we - * can use the full available buffer. - * image_offset = startup_32 - image_base - * Otherwise image_offset will be zero and has no effect on the calculations. - */ - subl rva(image_offset)(%ebp), %ebx -#endif - movl BP_kernel_alignment(%esi), %eax decl %eax addl %eax, %ebx @@ -335,20 +322,6 @@ SYM_CODE_START(startup_64) /* Start with the delta to where the kernel will run at. */ #ifdef CONFIG_RELOCATABLE leaq startup_32(%rip) /* - $startup_32 */, %rbp - -#ifdef CONFIG_EFI_STUB -/* - * If we were loaded via the EFI LoadImage service, startup_32 will be at an - * offset to the start of the space allocated for the image. efi_pe_entry will - * set up image_offset to tell us where the image actually starts, so that we - * can use the full available buffer. - * image_offset = startup_32 - image_base - * Otherwise image_offset will be zero and has no effect on the calculations. - */ - movl image_offset(%rip), %eax - subq %rax, %rbp -#endif - movl BP_kernel_alignment(%rsi), %eax decl %eax addq %rax, %rbp diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h index 8b4be7cecdb8eb73..b0994ae3bc23f84d 100644 --- a/arch/x86/include/asm/efi.h +++ b/arch/x86/include/asm/efi.h @@ -90,6 +90,8 @@ static inline void efi_fpu_end(void) } #ifdef CONFIG_X86_32 +#define EFI_X86_KERNEL_ALLOC_LIMIT (SZ_512M - 1) + #define arch_efi_call_virt_setup() \ ({ \ efi_fpu_begin(); \ @@ -103,8 +105,7 @@ static inline void efi_fpu_end(void) }) #else /* !CONFIG_X86_32 */ - -#define EFI_LOADER_SIGNATURE "EL64" +#define EFI_X86_KERNEL_ALLOC_LIMIT EFI_ALLOC_LIMIT extern asmlinkage u64 __efi_call(void *fp, ...); @@ -218,6 +219,8 @@ efi_status_t efi_set_virtual_address_map(unsigned long memory_map_size, #ifdef CONFIG_EFI_MIXED +#define EFI_ALLOC_LIMIT (efi_is_64bit() ? ULONG_MAX : U32_MAX) + #define ARCH_HAS_EFISTUB_WRAPPERS static inline bool efi_is_64bit(void) diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index b97d239e18ea25fc..5b4a1ce3d36808b4 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -164,6 +164,7 @@ static __always_inline void sev_es_nmi_complete(void) __sev_es_nmi_complete(); } extern int __init sev_es_efi_map_ghcbs(pgd_t *pgd); +extern void sev_enable(struct boot_params *bp); static inline int rmpadjust(unsigned long vaddr, bool rmp_psize, unsigned long attrs) { @@ -218,6 +219,7 @@ static inline void sev_es_ist_exit(void) { } static inline int sev_es_setup_ap_jump_table(struct real_mode_header *rmh) { return 0; } static inline void sev_es_nmi_complete(void) { } static inline int sev_es_efi_map_ghcbs(pgd_t *pgd) { return 0; } +static inline void sev_enable(struct boot_params *bp) { } static inline int pvalidate(unsigned long vaddr, bool rmp_psize, bool validate) { return 0; } static inline int rmpadjust(unsigned long vaddr, bool rmp_psize, unsigned long attrs) { return 0; } static inline void setup_ghcb(void) { } diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c index b4685da2b8d5c243..e976288728e975f1 100644 --- a/drivers/firmware/efi/libstub/x86-stub.c +++ b/drivers/firmware/efi/libstub/x86-stub.c @@ -15,17 +15,14 @@ #include #include #include +#include #include #include "efistub.h" #include "x86-stub.h" -/* Maximum physical address for 64-bit kernel with 4-level paging */ -#define MAXMEM_X86_64_4LEVEL (1ull << 46) - const efi_system_table_t *efi_system_table; const efi_dxe_services_table_t *efi_dxe_table; -u32 image_offset __section(".data"); static efi_loaded_image_t *image = NULL; static efi_memory_attribute_protocol_t *memattr; @@ -287,28 +284,6 @@ void efi_adjust_memory_range_protection(unsigned long start, } } -extern const u8 startup_32[], startup_64[]; - -static void -setup_memory_protection(unsigned long image_base, unsigned long image_size) -{ -#ifdef CONFIG_64BIT - if (image_base != (unsigned long)startup_32) - efi_adjust_memory_range_protection(image_base, image_size); -#else - /* - * Clear protection flags on a whole range of possible - * addresses used for KASLR. We don't need to do that - * on x86_64, since KASLR/extraction is performed after - * dedicated identity page tables are built and we only - * need to remove possible protection on relocated image - * itself disregarding further relocations. - */ - efi_adjust_memory_range_protection(LOAD_PHYSICAL_ADDR, - KERNEL_IMAGE_SIZE - LOAD_PHYSICAL_ADDR); -#endif -} - static void setup_unaccepted_memory(void) { efi_guid_t mem_acceptance_proto = OVMF_SEV_MEMORY_ACCEPTANCE_PROTOCOL_GUID; @@ -334,9 +309,7 @@ static void setup_unaccepted_memory(void) static const efi_char16_t apple[] = L"Apple"; -static void setup_quirks(struct boot_params *boot_params, - unsigned long image_base, - unsigned long image_size) +static void setup_quirks(struct boot_params *boot_params) { efi_char16_t *fw_vendor = (efi_char16_t *)(unsigned long) efi_table_attr(efi_system_table, fw_vendor); @@ -345,9 +318,6 @@ static void setup_quirks(struct boot_params *boot_params, if (IS_ENABLED(CONFIG_APPLE_PROPERTIES)) retrieve_apple_device_properties(boot_params); } - - if (IS_ENABLED(CONFIG_EFI_DXE_MEM_ATTRIBUTES)) - setup_memory_protection(image_base, image_size); } /* @@ -500,7 +470,6 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, } image_base = efi_table_attr(image, image_base); - image_offset = (void *)startup_32 - image_base; status = efi_allocate_pages(sizeof(struct boot_params), (unsigned long *)&boot_params, ULONG_MAX); @@ -804,6 +773,61 @@ static bool have_unsupported_snp_features(void) return false; } +static void efi_get_seed(void *seed, int size) +{ + efi_get_random_bytes(size, seed); + + /* + * This only updates seed[0] when running on 32-bit, but in that case, + * seed[1] is not used anyway, as there is no virtual KASLR on 32-bit. + */ + *(unsigned long *)seed ^= kaslr_get_random_long("EFI"); +} + +static void error(char *str) +{ + efi_warn("Decompression failed: %s\n", str); +} + +static efi_status_t efi_decompress_kernel(unsigned long *kernel_entry) +{ + unsigned long virt_addr = LOAD_PHYSICAL_ADDR; + unsigned long addr, alloc_size, entry; + efi_status_t status; + u32 seed[2] = {}; + + /* determine the required size of the allocation */ + alloc_size = ALIGN(max_t(unsigned long, output_len, kernel_total_size), + MIN_KERNEL_ALIGN); + + if (IS_ENABLED(CONFIG_RANDOMIZE_BASE) && !efi_nokaslr) { + u64 range = KERNEL_IMAGE_SIZE - LOAD_PHYSICAL_ADDR - kernel_total_size; + + efi_get_seed(seed, sizeof(seed)); + + virt_addr += (range * seed[1]) >> 32; + virt_addr &= ~(CONFIG_PHYSICAL_ALIGN - 1); + } + + status = efi_random_alloc(alloc_size, CONFIG_PHYSICAL_ALIGN, &addr, + seed[0], EFI_LOADER_CODE, + EFI_X86_KERNEL_ALLOC_LIMIT); + if (status != EFI_SUCCESS) + return status; + + entry = decompress_kernel((void *)addr, virt_addr, error); + if (entry == ULONG_MAX) { + efi_free(alloc_size, addr); + return EFI_LOAD_ERROR; + } + + *kernel_entry = addr + entry; + + efi_adjust_memory_range_protection(addr, kernel_total_size); + + return EFI_SUCCESS; +} + static void __noreturn enter_kernel(unsigned long kernel_addr, struct boot_params *boot_params) { @@ -823,10 +847,9 @@ void __noreturn efi_stub_entry(efi_handle_t handle, struct boot_params *boot_params) { efi_guid_t guid = EFI_MEMORY_ATTRIBUTE_PROTOCOL_GUID; - unsigned long bzimage_addr = (unsigned long)startup_32; - unsigned long buffer_start, buffer_end; struct setup_header *hdr = &boot_params->hdr; const struct linux_efi_initrd *initrd = NULL; + unsigned long kernel_entry; efi_status_t status; efi_system_table = sys_table_arg; @@ -855,60 +878,6 @@ void __noreturn efi_stub_entry(efi_handle_t handle, goto fail; } - /* - * If the kernel isn't already loaded at a suitable address, - * relocate it. - * - * It must be loaded above LOAD_PHYSICAL_ADDR. - * - * The maximum address for 64-bit is 1 << 46 for 4-level paging. This - * is defined as the macro MAXMEM, but unfortunately that is not a - * compile-time constant if 5-level paging is configured, so we instead - * define our own macro for use here. - * - * For 32-bit, the maximum address is complicated to figure out, for - * now use KERNEL_IMAGE_SIZE, which will be 512MiB, the same as what - * KASLR uses. - * - * Also relocate it if image_offset is zero, i.e. the kernel wasn't - * loaded by LoadImage, but rather by a bootloader that called the - * handover entry. The reason we must always relocate in this case is - * to handle the case of systemd-boot booting a unified kernel image, - * which is a PE executable that contains the bzImage and an initrd as - * COFF sections. The initrd section is placed after the bzImage - * without ensuring that there are at least init_size bytes available - * for the bzImage, and thus the compressed kernel's startup code may - * overwrite the initrd unless it is moved out of the way. - */ - - buffer_start = ALIGN(bzimage_addr - image_offset, - hdr->kernel_alignment); - buffer_end = buffer_start + hdr->init_size; - - if ((buffer_start < LOAD_PHYSICAL_ADDR) || - (IS_ENABLED(CONFIG_X86_32) && buffer_end > KERNEL_IMAGE_SIZE) || - (IS_ENABLED(CONFIG_X86_64) && buffer_end > MAXMEM_X86_64_4LEVEL) || - (image_offset == 0)) { - extern char _bss[]; - - status = efi_relocate_kernel(&bzimage_addr, - (unsigned long)_bss - bzimage_addr, - hdr->init_size, - hdr->pref_address, - hdr->kernel_alignment, - LOAD_PHYSICAL_ADDR); - if (status != EFI_SUCCESS) { - efi_err("efi_relocate_kernel() failed!\n"); - goto fail; - } - /* - * Now that we've copied the kernel elsewhere, we no longer - * have a set up block before startup_32(), so reset image_offset - * to zero in case it was set earlier. - */ - image_offset = 0; - } - #ifdef CONFIG_CMDLINE_BOOL status = efi_parse_options(CONFIG_CMDLINE); if (status != EFI_SUCCESS) { @@ -926,6 +895,12 @@ void __noreturn efi_stub_entry(efi_handle_t handle, } } + status = efi_decompress_kernel(&kernel_entry); + if (status != EFI_SUCCESS) { + efi_err("Failed to decompress kernel\n"); + goto fail; + } + /* * At this point, an initrd may already have been loaded by the * bootloader and passed via bootparams. We permit an initrd loaded @@ -965,7 +940,7 @@ void __noreturn efi_stub_entry(efi_handle_t handle, setup_efi_pci(boot_params); - setup_quirks(boot_params, bzimage_addr, buffer_end - buffer_start); + setup_quirks(boot_params); setup_unaccepted_memory(); @@ -975,12 +950,15 @@ void __noreturn efi_stub_entry(efi_handle_t handle, goto fail; } + /* + * Call the SEV init code while still running with the firmware's + * GDT/IDT, so #VC exceptions will be handled by EFI. + */ + sev_enable(boot_params); + efi_5level_switch(); - if (IS_ENABLED(CONFIG_X86_64)) - bzimage_addr += startup_64 - startup_32; - - enter_kernel(bzimage_addr, boot_params); + enter_kernel(kernel_entry, boot_params); fail: efi_err("efi_stub_entry() failed!\n");