Merge tag 'x86_boot_for_v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull x86 boot updates from Borislav Petkov:
"A of early boot cleanups and fixes.

- Do some spring cleaning to the compressed boot code by moving the
EFI mixed-mode code to a separate compilation unit, the AMD memory
encryption early code where it belongs and fixing up build
dependencies. Make the deprecated EFI handover protocol optional
with the goal of removing it at some point (Ard Biesheuvel)

- Skip realmode init code on Xen PV guests as it is not needed there

- Remove an old 32-bit PIC code compiler workaround"

* tag 'x86_boot_for_v6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/boot: Remove x86_32 PIC using %ebx workaround
x86/boot: Skip realmode init code when running as Xen PV guest
x86/efi: Make the deprecated EFI handover protocol optional
x86/boot/compressed: Only build mem_encrypt.S if AMD_MEM_ENCRYPT=y
x86/boot/compressed: Adhere to calling convention in get_sev_encryption_bit()
x86/boot/compressed: Move startup32_check_sev_cbit() out of head_64.S
x86/boot/compressed: Move startup32_check_sev_cbit() into .text
x86/boot/compressed: Move startup32_load_idt() out of head_64.S
x86/boot/compressed: Move startup32_load_idt() into .text section
x86/boot/compressed: Pull global variable reference into startup32_load_idt()
x86/boot/compressed: Avoid touching ECX in startup32_set_idt_entry()
x86/boot/compressed: Simplify IDT/GDT preserve/restore in the EFI thunk
x86/boot/compressed, efi: Merge multiple definitions of image_offset into one
x86/boot/compressed: Move efi32_pe_entry() out of head_64.S
x86/boot/compressed: Move efi32_entry out of head_64.S
x86/boot/compressed: Move efi32_pe_entry into .text section
x86/boot/compressed: Move bootargs parsing out of 32-bit startup code
x86/boot/compressed: Move 32-bit entrypoint code into .text section
x86/boot/compressed: Rename efi_thunk_64.S to efi-mixed.S

arch/x86/Kconfig

···
 
 	  See Documentation/admin-guide/efi-stub.rst for more information.
 
+config EFI_HANDOVER_PROTOCOL
+	bool "EFI handover protocol (DEPRECATED)"
+	depends on EFI_STUB
+	default y
+	help
+	  Select this in order to include support for the deprecated EFI
+	  handover protocol, which defines alternative entry points into the
+	  EFI stub.  This is a practice that has no basis in the UEFI
+	  specification, and requires a priori knowledge on the part of the
+	  bootloader about Linux/x86 specific ways of passing the command line
+	  and initrd, and where in memory those assets may be loaded.
+
+	  If in doubt, say Y. Even though the corresponding support is not
+	  present in upstream GRUB or other bootloaders, most distros build
+	  GRUB with numerous downstream patches applied, and may rely on the
+	  handover protocol as as result.
+
 config EFI_MIXED
 	bool "EFI mixed-mode support"
 	depends on EFI_STUB && X86_64

arch/x86/boot/compressed/Makefile

···
 ifdef CONFIG_X86_64
 	vmlinux-objs-y += $(obj)/ident_map_64.o
 	vmlinux-objs-y += $(obj)/idt_64.o $(obj)/idt_handlers_64.o
-	vmlinux-objs-y += $(obj)/mem_encrypt.o
+	vmlinux-objs-$(CONFIG_AMD_MEM_ENCRYPT) += $(obj)/mem_encrypt.o
 	vmlinux-objs-y += $(obj)/pgtable_64.o
 	vmlinux-objs-$(CONFIG_AMD_MEM_ENCRYPT) += $(obj)/sev.o
 endif
···
 vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o
 vmlinux-objs-$(CONFIG_INTEL_TDX_GUEST) += $(obj)/tdx.o $(obj)/tdcall.o
 
-vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o
 vmlinux-objs-$(CONFIG_EFI) += $(obj)/efi.o
-efi-obj-$(CONFIG_EFI_STUB) = $(objtree)/drivers/firmware/efi/libstub/lib.a
+vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_mixed.o
+vmlinux-objs-$(CONFIG_EFI_STUB) += $(objtree)/drivers/firmware/efi/libstub/lib.a
 
-$(obj)/vmlinux: $(vmlinux-objs-y) $(efi-obj-y) FORCE
+$(obj)/vmlinux: $(vmlinux-objs-y) FORCE
 	$(call if_changed,ld)
 
 OBJCOPYFLAGS_vmlinux.bin :=  -R .comment -S

arch/x86/boot/compressed/efi_mixed.S

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2014, 2015 Intel Corporation; author Matt Fleming
+ *
+ * Early support for invoking 32-bit EFI services from a 64-bit kernel.
+ *
+ * Because this thunking occurs before ExitBootServices() we have to
+ * restore the firmware's 32-bit GDT and IDT before we make EFI service
+ * calls.
+ *
+ * On the plus side, we don't have to worry about mangling 64-bit
+ * addresses into 32-bits because we're executing with an identity
+ * mapped pagetable and haven't transitioned to 64-bit virtual addresses
+ * yet.
+ */
+
+#include <linux/linkage.h>
+#include <asm/msr.h>
+#include <asm/page_types.h>
+#include <asm/processor-flags.h>
+#include <asm/segment.h>
+
+	.code64
+	.text
+/*
+ * When booting in 64-bit mode on 32-bit EFI firmware, startup_64_mixed_mode()
+ * is the first thing that runs after switching to long mode. Depending on
+ * whether the EFI handover protocol or the compat entry point was used to
+ * enter the kernel, it will either branch to the 64-bit EFI handover
+ * entrypoint at offset 0x390 in the image, or to the 64-bit EFI PE/COFF
+ * entrypoint efi_pe_entry(). In the former case, the bootloader must provide a
+ * struct bootparams pointer as the third argument, so the presence of such a
+ * pointer is used to disambiguate.
+ *
+ *                                                             +--------------+
+ *  +------------------+     +------------+            +------>| efi_pe_entry |
+ *  | efi32_pe_entry   |---->|            |            |       +-----------+--+
+ *  +------------------+     |            |     +------+----------------+  |
+ *                           | startup_32 |---->| startup_64_mixed_mode |  |
+ *  +------------------+     |            |     +------+----------------+  V
+ *  | efi32_stub_entry |---->|            |            |     +------------------+
+ *  +------------------+     +------------+            +---->| efi64_stub_entry |
+ *                                                           +-------------+----+
+ *                           +------------+     +----------+               |
+ *                           | startup_64 |<----| efi_main |<--------------+
+ *                           +------------+     +----------+
+ */
+SYM_FUNC_START(startup_64_mixed_mode)
+	lea	efi32_boot_args(%rip), %rdx
+	mov	0(%rdx), %edi
+	mov	4(%rdx), %esi
+	mov	8(%rdx), %edx		// saved bootparams pointer
+	test	%edx, %edx
+	jnz	efi64_stub_entry
+	/*
+	 * efi_pe_entry uses MS calling convention, which requires 32 bytes of
+	 * shadow space on the stack even if all arguments are passed in
+	 * registers. We also need an additional 8 bytes for the space that
+	 * would be occupied by the return address, and this also results in
+	 * the correct stack alignment for entry.
+	 */
+	sub	$40, %rsp
+	mov	%rdi, %rcx		// MS calling convention
+	mov	%rsi, %rdx
+	jmp	efi_pe_entry
+SYM_FUNC_END(startup_64_mixed_mode)
+
+SYM_FUNC_START(__efi64_thunk)
+	push	%rbp
+	push	%rbx
+
+	movl	%ds, %eax
+	push	%rax
+	movl	%es, %eax
+	push	%rax
+	movl	%ss, %eax
+	push	%rax
+
+	/* Copy args passed on stack */
+	movq	0x30(%rsp), %rbp
+	movq	0x38(%rsp), %rbx
+	movq	0x40(%rsp), %rax
+
+	/*
+	 * Convert x86-64 ABI params to i386 ABI
+	 */
+	subq	$64, %rsp
+	movl	%esi, 0x0(%rsp)
+	movl	%edx, 0x4(%rsp)
+	movl	%ecx, 0x8(%rsp)
+	movl	%r8d, 0xc(%rsp)
+	movl	%r9d, 0x10(%rsp)
+	movl	%ebp, 0x14(%rsp)
+	movl	%ebx, 0x18(%rsp)
+	movl	%eax, 0x1c(%rsp)
+
+	leaq	0x20(%rsp), %rbx
+	sgdt	(%rbx)
+	sidt	16(%rbx)
+
+	leaq	1f(%rip), %rbp
+
+	/*
+	 * Switch to IDT and GDT with 32-bit segments. These are the firmware
+	 * GDT and IDT that were installed when the kernel started executing.
+	 * The pointers were saved by the efi32_entry() routine below.
+	 *
+	 * Pass the saved DS selector to the 32-bit code, and use far return to
+	 * restore the saved CS selector.
+	 */
+	lidt	efi32_boot_idt(%rip)
+	lgdt	efi32_boot_gdt(%rip)
+
+	movzwl	efi32_boot_ds(%rip), %edx
+	movzwq	efi32_boot_cs(%rip), %rax
+	pushq	%rax
+	leaq	efi_enter32(%rip), %rax
+	pushq	%rax
+	lretq
+
+1:	addq	$64, %rsp
+	movq	%rdi, %rax
+
+	pop	%rbx
+	movl	%ebx, %ss
+	pop	%rbx
+	movl	%ebx, %es
+	pop	%rbx
+	movl	%ebx, %ds
+	/* Clear out 32-bit selector from FS and GS */
+	xorl	%ebx, %ebx
+	movl	%ebx, %fs
+	movl	%ebx, %gs
+
+	pop	%rbx
+	pop	%rbp
+	RET
+SYM_FUNC_END(__efi64_thunk)
+
+	.code32
+/*
+ * EFI service pointer must be in %edi.
+ *
+ * The stack should represent the 32-bit calling convention.
+ */
+SYM_FUNC_START_LOCAL(efi_enter32)
+	/* Load firmware selector into data and stack segment registers */
+	movl	%edx, %ds
+	movl	%edx, %es
+	movl	%edx, %fs
+	movl	%edx, %gs
+	movl	%edx, %ss
+
+	/* Reload pgtables */
+	movl	%cr3, %eax
+	movl	%eax, %cr3
+
+	/* Disable paging */
+	movl	%cr0, %eax
+	btrl	$X86_CR0_PG_BIT, %eax
+	movl	%eax, %cr0
+
+	/* Disable long mode via EFER */
+	movl	$MSR_EFER, %ecx
+	rdmsr
+	btrl	$_EFER_LME, %eax
+	wrmsr
+
+	call	*%edi
+
+	/* We must preserve return value */
+	movl	%eax, %edi
+
+	/*
+	 * Some firmware will return with interrupts enabled. Be sure to
+	 * disable them before we switch GDTs and IDTs.
+	 */
+	cli
+
+	lidtl	16(%ebx)
+	lgdtl	(%ebx)
+
+	movl	%cr4, %eax
+	btsl	$(X86_CR4_PAE_BIT), %eax
+	movl	%eax, %cr4
+
+	movl	%cr3, %eax
+	movl	%eax, %cr3
+
+	movl	$MSR_EFER, %ecx
+	rdmsr
+	btsl	$_EFER_LME, %eax
+	wrmsr
+
+	xorl	%eax, %eax
+	lldt	%ax
+
+	pushl	$__KERNEL_CS
+	pushl	%ebp
+
+	/* Enable paging */
+	movl	%cr0, %eax
+	btsl	$X86_CR0_PG_BIT, %eax
+	movl	%eax, %cr0
+	lret
+SYM_FUNC_END(efi_enter32)
+
+/*
+ * This is the common EFI stub entry point for mixed mode.
+ *
+ * Arguments:	%ecx	image handle
+ * 		%edx	EFI system table pointer
+ *		%esi	struct bootparams pointer (or NULL when not using
+ *			the EFI handover protocol)
+ *
+ * Since this is the point of no return for ordinary execution, no registers
+ * are considered live except for the function parameters. [Note that the EFI
+ * stub may still exit and return to the firmware using the Exit() EFI boot
+ * service.]
+ */
+SYM_FUNC_START(efi32_entry)
+	call	1f
+1:	pop	%ebx
+
+	/* Save firmware GDTR and code/data selectors */
+	sgdtl	(efi32_boot_gdt - 1b)(%ebx)
+	movw	%cs, (efi32_boot_cs - 1b)(%ebx)
+	movw	%ds, (efi32_boot_ds - 1b)(%ebx)
+
+	/* Store firmware IDT descriptor */
+	sidtl	(efi32_boot_idt - 1b)(%ebx)
+
+	/* Store boot arguments */
+	leal	(efi32_boot_args - 1b)(%ebx), %ebx
+	movl	%ecx, 0(%ebx)
+	movl	%edx, 4(%ebx)
+	movl	%esi, 8(%ebx)
+	movb	$0x0, 12(%ebx)          // efi_is64
+
+	/* Disable paging */
+	movl	%cr0, %eax
+	btrl	$X86_CR0_PG_BIT, %eax
+	movl	%eax, %cr0
+
+	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)
+ */
+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
+
+	call	verify_cpu			// check for long mode support
+	testl	%eax, %eax
+	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
+
+2:	popl	%edi				// restore callee-save registers
+	popl	%ebx
+	leave
+	RET
+SYM_FUNC_END(efi32_pe_entry)
+
+	.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)
+	.word	0
+	.quad	0
+SYM_DATA_END(efi32_boot_gdt)
+
+SYM_DATA_START_LOCAL(efi32_boot_idt)
+	.word	0
+	.quad	0
+SYM_DATA_END(efi32_boot_idt)
+
+SYM_DATA_LOCAL(efi32_boot_cs, .word 0)
+SYM_DATA_LOCAL(efi32_boot_ds, .word 0)
+SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0)
+SYM_DATA(efi_is64, .byte 1)

arch/x86/boot/compressed/efi_thunk_64.S

···
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * Copyright (C) 2014, 2015 Intel Corporation; author Matt Fleming
- *
- * Early support for invoking 32-bit EFI services from a 64-bit kernel.
- *
- * Because this thunking occurs before ExitBootServices() we have to
- * restore the firmware's 32-bit GDT and IDT before we make EFI service
- * calls.
- *
- * On the plus side, we don't have to worry about mangling 64-bit
- * addresses into 32-bits because we're executing with an identity
- * mapped pagetable and haven't transitioned to 64-bit virtual addresses
- * yet.
- */
-
-#include <linux/linkage.h>
-#include <asm/msr.h>
-#include <asm/page_types.h>
-#include <asm/processor-flags.h>
-#include <asm/segment.h>
-
-	.code64
-	.text
-SYM_FUNC_START(__efi64_thunk)
-	push	%rbp
-	push	%rbx
-
-	movl	%ds, %eax
-	push	%rax
-	movl	%es, %eax
-	push	%rax
-	movl	%ss, %eax
-	push	%rax
-
-	/* Copy args passed on stack */
-	movq	0x30(%rsp), %rbp
-	movq	0x38(%rsp), %rbx
-	movq	0x40(%rsp), %rax
-
-	/*
-	 * Convert x86-64 ABI params to i386 ABI
-	 */
-	subq	$64, %rsp
-	movl	%esi, 0x0(%rsp)
-	movl	%edx, 0x4(%rsp)
-	movl	%ecx, 0x8(%rsp)
-	movl	%r8d, 0xc(%rsp)
-	movl	%r9d, 0x10(%rsp)
-	movl	%ebp, 0x14(%rsp)
-	movl	%ebx, 0x18(%rsp)
-	movl	%eax, 0x1c(%rsp)
-
-	leaq	0x20(%rsp), %rbx
-	sgdt	(%rbx)
-
-	addq	$16, %rbx
-	sidt	(%rbx)
-
-	leaq	1f(%rip), %rbp
-
-	/*
-	 * Switch to IDT and GDT with 32-bit segments. This is the firmware GDT
-	 * and IDT that was installed when the kernel started executing. The
-	 * pointers were saved at the EFI stub entry point in head_64.S.
-	 *
-	 * Pass the saved DS selector to the 32-bit code, and use far return to
-	 * restore the saved CS selector.
-	 */
-	leaq	efi32_boot_idt(%rip), %rax
-	lidt	(%rax)
-	leaq	efi32_boot_gdt(%rip), %rax
-	lgdt	(%rax)
-
-	movzwl	efi32_boot_ds(%rip), %edx
-	movzwq	efi32_boot_cs(%rip), %rax
-	pushq	%rax
-	leaq	efi_enter32(%rip), %rax
-	pushq	%rax
-	lretq
-
-1:	addq	$64, %rsp
-	movq	%rdi, %rax
-
-	pop	%rbx
-	movl	%ebx, %ss
-	pop	%rbx
-	movl	%ebx, %es
-	pop	%rbx
-	movl	%ebx, %ds
-	/* Clear out 32-bit selector from FS and GS */
-	xorl	%ebx, %ebx
-	movl	%ebx, %fs
-	movl	%ebx, %gs
-
-	pop	%rbx
-	pop	%rbp
-	RET
-SYM_FUNC_END(__efi64_thunk)
-
-	.code32
-/*
- * EFI service pointer must be in %edi.
- *
- * The stack should represent the 32-bit calling convention.
- */
-SYM_FUNC_START_LOCAL(efi_enter32)
-	/* Load firmware selector into data and stack segment registers */
-	movl	%edx, %ds
-	movl	%edx, %es
-	movl	%edx, %fs
-	movl	%edx, %gs
-	movl	%edx, %ss
-
-	/* Reload pgtables */
-	movl	%cr3, %eax
-	movl	%eax, %cr3
-
-	/* Disable paging */
-	movl	%cr0, %eax
-	btrl	$X86_CR0_PG_BIT, %eax
-	movl	%eax, %cr0
-
-	/* Disable long mode via EFER */
-	movl	$MSR_EFER, %ecx
-	rdmsr
-	btrl	$_EFER_LME, %eax
-	wrmsr
-
-	call	*%edi
-
-	/* We must preserve return value */
-	movl	%eax, %edi
-
-	/*
-	 * Some firmware will return with interrupts enabled. Be sure to
-	 * disable them before we switch GDTs and IDTs.
-	 */
-	cli
-
-	lidtl	(%ebx)
-	subl	$16, %ebx
-
-	lgdtl	(%ebx)
-
-	movl	%cr4, %eax
-	btsl	$(X86_CR4_PAE_BIT), %eax
-	movl	%eax, %cr4
-
-	movl	%cr3, %eax
-	movl	%eax, %cr3
-
-	movl	$MSR_EFER, %ecx
-	rdmsr
-	btsl	$_EFER_LME, %eax
-	wrmsr
-
-	xorl	%eax, %eax
-	lldt	%ax
-
-	pushl	$__KERNEL_CS
-	pushl	%ebp
-
-	/* Enable paging */
-	movl	%cr0, %eax
-	btsl	$X86_CR0_PG_BIT, %eax
-	movl	%eax, %cr0
-	lret
-SYM_FUNC_END(efi_enter32)
-
-	.data
-	.balign	8
-SYM_DATA_START(efi32_boot_gdt)
-	.word	0
-	.quad	0
-SYM_DATA_END(efi32_boot_gdt)
-
-SYM_DATA_START(efi32_boot_idt)
-	.word	0
-	.quad	0
-SYM_DATA_END(efi32_boot_idt)
-
-SYM_DATA_START(efi32_boot_cs)
-	.word	0
-SYM_DATA_END(efi32_boot_cs)
-
-SYM_DATA_START(efi32_boot_ds)
-	.word	0
-SYM_DATA_END(efi32_boot_ds)

arch/x86/boot/compressed/head_32.S

···
 	.quad	0x00cf92000000ffff	/* __KERNEL_DS */
 SYM_DATA_END_LABEL(gdt, SYM_L_LOCAL, gdt_end)
 
-#ifdef CONFIG_EFI_STUB
-SYM_DATA(image_offset, .long 0)
-#endif
-
 /*
  * Stack and heap for uncompression
  */

arch/x86/boot/compressed/head_64.S

···
 1:
 
 	/* Setup Exception handling for SEV-ES */
+#ifdef CONFIG_AMD_MEM_ENCRYPT
 	call	startup32_load_idt
+#endif
 
 	/* Make sure cpu supports long mode. */
 	call	verify_cpu
···
   */
 	/*
 	 * If SEV is active then set the encryption mask in the page tables.
-	 * This will insure that when the kernel is copied and decompressed
+	 * This will ensure that when the kernel is copied and decompressed
 	 * it will be done so encrypted.
 	 */
-	call	get_sev_encryption_bit
 	xorl	%edx, %edx
 #ifdef	CONFIG_AMD_MEM_ENCRYPT
+	call	get_sev_encryption_bit
+	xorl	%edx, %edx
 	testl	%eax, %eax
 	jz	1f
 	subl	$32, %eax	/* Encryption bit is always above bit 31 */
···
 	movl    $__BOOT_TSS, %eax
 	ltr	%ax
 
+#ifdef CONFIG_AMD_MEM_ENCRYPT
+	/* Check if the C-bit position is correct when SEV is active */
+	call	startup32_check_sev_cbit
+#endif
+
 	/*
 	 * Setup for the jump to 64bit mode
 	 *
···
 	 */
 	leal	rva(startup_64)(%ebp), %eax
 #ifdef CONFIG_EFI_MIXED
-	movl	rva(efi32_boot_args)(%ebp), %edi
-	testl	%edi, %edi
-	jz	1f
-	leal	rva(efi64_stub_entry)(%ebp), %eax
-	movl	rva(efi32_boot_args+4)(%ebp), %esi
-	movl	rva(efi32_boot_args+8)(%ebp), %edx	// saved bootparams pointer
-	testl	%edx, %edx
-	jnz	1f
-	/*
-	 * efi_pe_entry uses MS calling convention, which requires 32 bytes of
-	 * shadow space on the stack even if all arguments are passed in
-	 * registers. We also need an additional 8 bytes for the space that
-	 * would be occupied by the return address, and this also results in
-	 * the correct stack alignment for entry.
-	 */
-	subl	$40, %esp
-	leal	rva(efi_pe_entry)(%ebp), %eax
-	movl	%edi, %ecx			// MS calling convention
-	movl	%esi, %edx
+	cmpb	$1, rva(efi_is64)(%ebp)
+	je	1f
+	leal	rva(startup_64_mixed_mode)(%ebp), %eax
 1:
 #endif
-	/* Check if the C-bit position is correct when SEV is active */
-	call	startup32_check_sev_cbit
 
 	pushl	$__KERNEL_CS
 	pushl	%eax
···
 	lret
 SYM_FUNC_END(startup_32)
 
-#ifdef CONFIG_EFI_MIXED
+#if IS_ENABLED(CONFIG_EFI_MIXED) && IS_ENABLED(CONFIG_EFI_HANDOVER_PROTOCOL)
 	.org 0x190
 SYM_FUNC_START(efi32_stub_entry)
 	add	$0x4, %esp		/* Discard return address */
 	popl	%ecx
 	popl	%edx
 	popl	%esi
-
-	call	1f
-1:	pop	%ebp
-	subl	$ rva(1b), %ebp
-
-	movl	%esi, rva(efi32_boot_args+8)(%ebp)
-SYM_INNER_LABEL(efi32_pe_stub_entry, SYM_L_LOCAL)
-	movl	%ecx, rva(efi32_boot_args)(%ebp)
-	movl	%edx, rva(efi32_boot_args+4)(%ebp)
-	movb	$0, rva(efi_is64)(%ebp)
-
-	/* Save firmware GDTR and code/data selectors */
-	sgdtl	rva(efi32_boot_gdt)(%ebp)
-	movw	%cs, rva(efi32_boot_cs)(%ebp)
-	movw	%ds, rva(efi32_boot_ds)(%ebp)
-
-	/* Store firmware IDT descriptor */
-	sidtl	rva(efi32_boot_idt)(%ebp)
-
-	/* Disable paging */
-	movl	%cr0, %eax
-	btrl	$X86_CR0_PG_BIT, %eax
-	movl	%eax, %cr0
-
-	jmp	startup_32
+	jmp	efi32_entry
 SYM_FUNC_END(efi32_stub_entry)
 #endif
 
···
 SYM_CODE_END(startup_64)
 
 #ifdef CONFIG_EFI_STUB
+#ifdef CONFIG_EFI_HANDOVER_PROTOCOL
 	.org 0x390
+#endif
 SYM_FUNC_START(efi64_stub_entry)
 	and	$~0xf, %rsp			/* realign the stack */
 	movq	%rdx, %rbx			/* save boot_params pointer */
···
 	jmp     1b
 SYM_FUNC_END(.Lno_longmode)
 
+	.globl	verify_cpu
 #include "../../kernel/verify_cpu.S"
 
 	.data
···
 	.quad	0
 	.endr
 SYM_DATA_END_LABEL(boot_idt, SYM_L_GLOBAL, boot_idt_end)
-
-#ifdef CONFIG_AMD_MEM_ENCRYPT
-SYM_DATA_START(boot32_idt_desc)
-	.word   boot32_idt_end - boot32_idt - 1
-	.long   0
-SYM_DATA_END(boot32_idt_desc)
-	.balign 8
-SYM_DATA_START(boot32_idt)
-	.rept 32
-	.quad 0
-	.endr
-SYM_DATA_END_LABEL(boot32_idt, SYM_L_GLOBAL, boot32_idt_end)
-#endif
-
-#ifdef CONFIG_EFI_STUB
-SYM_DATA(image_offset, .long 0)
-#endif
-#ifdef CONFIG_EFI_MIXED
-SYM_DATA_LOCAL(efi32_boot_args, .long 0, 0, 0)
-SYM_DATA(efi_is64, .byte 1)
-
-#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)
-
-	__HEAD
-	.code32
-SYM_FUNC_START(efi32_pe_entry)
-/*
- * efi_status_t efi32_pe_entry(efi_handle_t image_handle,
- *			       efi_system_table_32_t *sys_table)
- */
-
-	pushl	%ebp
-	movl	%esp, %ebp
-	pushl	%eax				// dummy push to allocate loaded_image
-
-	pushl	%ebx				// save callee-save registers
-	pushl	%edi
-
-	call	verify_cpu			// check for long mode support
-	testl	%eax, %eax
-	movl	$0x80000003, %eax		// EFI_UNSUPPORTED
-	jnz	2f
-
-	call	1f
-1:	pop	%ebx
-	subl	$ rva(1b), %ebx
-
-	/* Get the loaded image protocol pointer from the image handle */
-	leal	-4(%ebp), %eax
-	pushl	%eax				// &loaded_image
-	leal	rva(loaded_image_proto)(%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
-	movl	%ebx, %ebp			// startup_32 for efi32_pe_stub_entry
-	/*
-	 * 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, %ebx
-	movl	%ebx, rva(image_offset)(%ebp)	// save image_offset
-	jmp	efi32_pe_stub_entry
-
-2:	popl	%edi				// restore callee-save registers
-	popl	%ebx
-	leave
-	RET
-SYM_FUNC_END(efi32_pe_entry)
-
-	.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)
-#endif
-
-#ifdef CONFIG_AMD_MEM_ENCRYPT
-	__HEAD
-	.code32
-/*
- * Write an IDT entry into boot32_idt
- *
- * Parameters:
- *
- * %eax:	Handler address
- * %edx:	Vector number
- *
- * Physical offset is expected in %ebp
- */
-SYM_FUNC_START(startup32_set_idt_entry)
-	push    %ebx
-	push    %ecx
-
-	/* IDT entry address to %ebx */
-	leal    rva(boot32_idt)(%ebp), %ebx
-	shl	$3, %edx
-	addl    %edx, %ebx
-
-	/* Build IDT entry, lower 4 bytes */
-	movl    %eax, %edx
-	andl    $0x0000ffff, %edx	# Target code segment offset [15:0]
-	movl    $__KERNEL32_CS, %ecx	# Target code segment selector
-	shl     $16, %ecx
-	orl     %ecx, %edx
-
-	/* Store lower 4 bytes to IDT */
-	movl    %edx, (%ebx)
-
-	/* Build IDT entry, upper 4 bytes */
-	movl    %eax, %edx
-	andl    $0xffff0000, %edx	# Target code segment offset [31:16]
-	orl     $0x00008e00, %edx	# Present, Type 32-bit Interrupt Gate
-
-	/* Store upper 4 bytes to IDT */
-	movl    %edx, 4(%ebx)
-
-	pop     %ecx
-	pop     %ebx
-	RET
-SYM_FUNC_END(startup32_set_idt_entry)
-#endif
-
-SYM_FUNC_START(startup32_load_idt)
-#ifdef CONFIG_AMD_MEM_ENCRYPT
-	/* #VC handler */
-	leal    rva(startup32_vc_handler)(%ebp), %eax
-	movl    $X86_TRAP_VC, %edx
-	call    startup32_set_idt_entry
-
-	/* Load IDT */
-	leal	rva(boot32_idt)(%ebp), %eax
-	movl	%eax, rva(boot32_idt_desc+2)(%ebp)
-	lidt    rva(boot32_idt_desc)(%ebp)
-#endif
-	RET
-SYM_FUNC_END(startup32_load_idt)
-
-/*
- * Check for the correct C-bit position when the startup_32 boot-path is used.
- *
- * The check makes use of the fact that all memory is encrypted when paging is
- * disabled. The function creates 64 bits of random data using the RDRAND
- * instruction. RDRAND is mandatory for SEV guests, so always available. If the
- * hypervisor violates that the kernel will crash right here.
- *
- * The 64 bits of random data are stored to a memory location and at the same
- * time kept in the %eax and %ebx registers. Since encryption is always active
- * when paging is off the random data will be stored encrypted in main memory.
- *
- * Then paging is enabled. When the C-bit position is correct all memory is
- * still mapped encrypted and comparing the register values with memory will
- * succeed. An incorrect C-bit position will map all memory unencrypted, so that
- * the compare will use the encrypted random data and fail.
- */
-SYM_FUNC_START(startup32_check_sev_cbit)
-#ifdef CONFIG_AMD_MEM_ENCRYPT
-	pushl	%eax
-	pushl	%ebx
-	pushl	%ecx
-	pushl	%edx
-
-	/* Check for non-zero sev_status */
-	movl	rva(sev_status)(%ebp), %eax
-	testl	%eax, %eax
-	jz	4f
-
-	/*
-	 * Get two 32-bit random values - Don't bail out if RDRAND fails
-	 * because it is better to prevent forward progress if no random value
-	 * can be gathered.
-	 */
-1:	rdrand	%eax
-	jnc	1b
-2:	rdrand	%ebx
-	jnc	2b
-
-	/* Store to memory and keep it in the registers */
-	movl	%eax, rva(sev_check_data)(%ebp)
-	movl	%ebx, rva(sev_check_data+4)(%ebp)
-
-	/* Enable paging to see if encryption is active */
-	movl	%cr0, %edx			 /* Backup %cr0 in %edx */
-	movl	$(X86_CR0_PG | X86_CR0_PE), %ecx /* Enable Paging and Protected mode */
-	movl	%ecx, %cr0
-
-	cmpl	%eax, rva(sev_check_data)(%ebp)
-	jne	3f
-	cmpl	%ebx, rva(sev_check_data+4)(%ebp)
-	jne	3f
-
-	movl	%edx, %cr0	/* Restore previous %cr0 */
-
-	jmp	4f
-
-3:	/* Check failed - hlt the machine */
-	hlt
-	jmp	3b
-
-4:
-	popl	%edx
-	popl	%ecx
-	popl	%ebx
-	popl	%eax
-#endif
-	RET
-SYM_FUNC_END(startup32_check_sev_cbit)
 
 /*
  * Stack and heap for uncompression

arch/x86/boot/compressed/mem_encrypt.S

···
 #include <asm/processor-flags.h>
 #include <asm/msr.h>
 #include <asm/asm-offsets.h>
+#include <asm/segment.h>
+#include <asm/trapnr.h>
 
 	.text
 	.code32
 SYM_FUNC_START(get_sev_encryption_bit)
-	xor	%eax, %eax
-
-#ifdef CONFIG_AMD_MEM_ENCRYPT
 	push	%ebx
-	push	%ecx
-	push	%edx
 
 	movl	$0x80000000, %eax	/* CPUID to check the highest leaf */
 	cpuid
···
 	xor	%eax, %eax
 
 .Lsev_exit:
-	pop	%edx
-	pop	%ecx
 	pop	%ebx
-
-#endif	/* CONFIG_AMD_MEM_ENCRYPT */
-
 	RET
 SYM_FUNC_END(get_sev_encryption_bit)
 
···
 	jmp	1b
 SYM_CODE_END(sev_es_req_cpuid)
 
-SYM_CODE_START(startup32_vc_handler)
+SYM_CODE_START_LOCAL(startup32_vc_handler)
 	pushl	%eax
 	pushl	%ebx
 	pushl	%ecx
···
 	jmp .Lfail
 SYM_CODE_END(startup32_vc_handler)
 
+/*
+ * Write an IDT entry into boot32_idt
+ *
+ * Parameters:
+ *
+ * %eax:	Handler address
+ * %edx:	Vector number
+ * %ecx:	IDT address
+ */
+SYM_FUNC_START_LOCAL(startup32_set_idt_entry)
+	/* IDT entry address to %ecx */
+	leal	(%ecx, %edx, 8), %ecx
+
+	/* Build IDT entry, lower 4 bytes */
+	movl    %eax, %edx
+	andl    $0x0000ffff, %edx		# Target code segment offset [15:0]
+	orl	$(__KERNEL32_CS << 16), %edx	# Target code segment selector
+
+	/* Store lower 4 bytes to IDT */
+	movl    %edx, (%ecx)
+
+	/* Build IDT entry, upper 4 bytes */
+	movl    %eax, %edx
+	andl    $0xffff0000, %edx	# Target code segment offset [31:16]
+	orl     $0x00008e00, %edx	# Present, Type 32-bit Interrupt Gate
+
+	/* Store upper 4 bytes to IDT */
+	movl    %edx, 4(%ecx)
+
+	RET
+SYM_FUNC_END(startup32_set_idt_entry)
+
+SYM_FUNC_START(startup32_load_idt)
+	push	%ebp
+	push	%ebx
+
+	call	1f
+1:	pop	%ebp
+
+	leal    (boot32_idt - 1b)(%ebp), %ebx
+
+	/* #VC handler */
+	leal    (startup32_vc_handler - 1b)(%ebp), %eax
+	movl    $X86_TRAP_VC, %edx
+	movl	%ebx, %ecx
+	call    startup32_set_idt_entry
+
+	/* Load IDT */
+	leal	(boot32_idt_desc - 1b)(%ebp), %ecx
+	movl	%ebx, 2(%ecx)
+	lidt    (%ecx)
+
+	pop	%ebx
+	pop	%ebp
+	RET
+SYM_FUNC_END(startup32_load_idt)
+
+/*
+ * Check for the correct C-bit position when the startup_32 boot-path is used.
+ *
+ * The check makes use of the fact that all memory is encrypted when paging is
+ * disabled. The function creates 64 bits of random data using the RDRAND
+ * instruction. RDRAND is mandatory for SEV guests, so always available. If the
+ * hypervisor violates that the kernel will crash right here.
+ *
+ * The 64 bits of random data are stored to a memory location and at the same
+ * time kept in the %eax and %ebx registers. Since encryption is always active
+ * when paging is off the random data will be stored encrypted in main memory.
+ *
+ * Then paging is enabled. When the C-bit position is correct all memory is
+ * still mapped encrypted and comparing the register values with memory will
+ * succeed. An incorrect C-bit position will map all memory unencrypted, so that
+ * the compare will use the encrypted random data and fail.
+ */
+SYM_FUNC_START(startup32_check_sev_cbit)
+	pushl	%ebx
+	pushl	%ebp
+
+	call	0f
+0:	popl	%ebp
+
+	/* Check for non-zero sev_status */
+	movl	(sev_status - 0b)(%ebp), %eax
+	testl	%eax, %eax
+	jz	4f
+
+	/*
+	 * Get two 32-bit random values - Don't bail out if RDRAND fails
+	 * because it is better to prevent forward progress if no random value
+	 * can be gathered.
+	 */
+1:	rdrand	%eax
+	jnc	1b
+2:	rdrand	%ebx
+	jnc	2b
+
+	/* Store to memory and keep it in the registers */
+	leal	(sev_check_data - 0b)(%ebp), %ebp
+	movl	%eax, 0(%ebp)
+	movl	%ebx, 4(%ebp)
+
+	/* Enable paging to see if encryption is active */
+	movl	%cr0, %edx			 /* Backup %cr0 in %edx */
+	movl	$(X86_CR0_PG | X86_CR0_PE), %ecx /* Enable Paging and Protected mode */
+	movl	%ecx, %cr0
+
+	cmpl	%eax, 0(%ebp)
+	jne	3f
+	cmpl	%ebx, 4(%ebp)
+	jne	3f
+
+	movl	%edx, %cr0	/* Restore previous %cr0 */
+
+	jmp	4f
+
+3:	/* Check failed - hlt the machine */
+	hlt
+	jmp	3b
+
+4:
+	popl	%ebp
+	popl	%ebx
+	RET
+SYM_FUNC_END(startup32_check_sev_cbit)
+
 	.code64
 
 #include "../../kernel/sev_verify_cbit.S"
 
 	.data
 
-#ifdef CONFIG_AMD_MEM_ENCRYPT
 	.balign	8
 SYM_DATA(sme_me_mask,		.quad 0)
 SYM_DATA(sev_status,		.quad 0)
 SYM_DATA(sev_check_data,	.quad 0)
-#endif
+
+SYM_DATA_START_LOCAL(boot32_idt)
+	.rept	32
+	.quad	0
+	.endr
+SYM_DATA_END(boot32_idt)
+
+SYM_DATA_START_LOCAL(boot32_idt_desc)
+	.word	. - boot32_idt - 1
+	.long	0
+SYM_DATA_END(boot32_idt_desc)

arch/x86/boot/cpuflags.c

···
 	return !!((f0^f1) & mask);
 }
 
-/* Handle x86_32 PIC using ebx. */
-#if defined(__i386__) && defined(__PIC__)
-# define EBX_REG "=r"
-#else
-# define EBX_REG "=b"
-#endif
-
 void cpuid_count(u32 id, u32 count, u32 *a, u32 *b, u32 *c, u32 *d)
 {
-	asm volatile(".ifnc %%ebx,%3 ; movl  %%ebx,%3 ; .endif	\n\t"
-		     "cpuid					\n\t"
-		     ".ifnc %%ebx,%3 ; xchgl %%ebx,%3 ; .endif	\n\t"
-		    : "=a" (*a), "=c" (*c), "=d" (*d), EBX_REG (*b)
-		    : "a" (id), "c" (count)
+	asm volatile("cpuid"
+		     : "=a" (*a), "=b" (*b), "=c" (*c), "=d" (*d)
+		     : "0" (id), "2" (count)
 	);
 }
 

arch/x86/boot/header.S

···
 # define XLF1 0
 #endif
 
-#ifdef CONFIG_EFI_STUB
+#ifdef CONFIG_EFI_HANDOVER_PROTOCOL
 # ifdef CONFIG_EFI_MIXED
 #  define XLF23 (XLF_EFI_HANDOVER_32|XLF_EFI_HANDOVER_64)
 # else

arch/x86/boot/tools/build.c

···
 {
 	unsigned long addr = efi32_stub_entry;
 
+#ifdef CONFIG_EFI_HANDOVER_PROTOCOL
 #ifdef CONFIG_X86_64
 	/* Yes, this is really how we defined it :( */
 	addr = efi64_stub_entry - 0x200;
···
 #ifdef CONFIG_EFI_MIXED
 	if (efi32_stub_entry != addr)
 		die("32-bit and 64-bit EFI entry points do not match\n");
+#endif
 #endif
 	put_unaligned_le32(addr, &buf[0x264]);
 }

arch/x86/include/asm/realmode.h

···
 
 void reserve_real_mode(void);
 void load_trampoline_pgtable(void);
+void init_real_mode(void);
 
 #endif /* __ASSEMBLY__ */
 

arch/x86/include/asm/x86_init.h

···
  * 				possible in x86_early_init_platform_quirks() by
  * 				only using the current x86_hardware_subarch
  * 				semantics.
+ * @realmode_reserve:		reserve memory for realmode trampoline
+ * @realmode_init:		initialize realmode trampoline
  * @hyper:			x86 hypervisor specific runtime callbacks
  */
 struct x86_platform_ops {
···
 	void (*apic_post_init)(void);
 	struct x86_legacy_features legacy;
 	void (*set_legacy_features)(void);
+	void (*realmode_reserve)(void);
+	void (*realmode_init)(void);
 	struct x86_hyper_runtime hyper;
 	struct x86_guest guest;
 };

arch/x86/kernel/setup.c

···
 	 * Moreover, on machines with SandyBridge graphics or in setups that use
 	 * crashkernel the entire 1M is reserved anyway.
 	 */
-	reserve_real_mode();
+	x86_platform.realmode_reserve();
 
 	init_mem_mapping();
 

arch/x86/kernel/x86_init.c

···
 #include <asm/iommu.h>
 #include <asm/mach_traps.h>
 #include <asm/irqdomain.h>
+#include <asm/realmode.h>
 
 void x86_init_noop(void) { }
 void __init x86_init_uint_noop(unsigned int unused) { }
···
 	.get_nmi_reason			= default_get_nmi_reason,
 	.save_sched_clock_state		= tsc_save_sched_clock_state,
 	.restore_sched_clock_state	= tsc_restore_sched_clock_state,
+	.realmode_reserve		= reserve_real_mode,
+	.realmode_init			= init_real_mode,
 	.hyper.pin_vcpu			= x86_op_int_noop,
 
 	.guest = {

arch/x86/realmode/init.c

···
 	set_memory_x((unsigned long) text_start, text_size >> PAGE_SHIFT);
 }
 
-static int __init init_real_mode(void)
+void __init init_real_mode(void)
 {
 	if (!real_mode_header)
 		panic("Real mode trampoline was not allocated");
 
 	setup_real_mode();
 	set_real_mode_permissions();
+}
 
+static int __init do_init_real_mode(void)
+{
+	x86_platform.realmode_init();
 	return 0;
 }
-early_initcall(init_real_mode);
+early_initcall(do_init_real_mode);

arch/x86/xen/enlighten_pv.c

···
 	xen_vcpu_info_reset(0);
 
 	x86_platform.get_nmi_reason = xen_get_nmi_reason;
+	x86_platform.realmode_reserve = x86_init_noop;
+	x86_platform.realmode_init = x86_init_noop;
 
 	x86_init.resources.memory_setup = xen_memory_setup;
 	x86_init.irqs.intr_mode_select	= x86_init_noop;

drivers/firmware/efi/libstub/x86-stub.c

···
 
 const efi_system_table_t *efi_system_table;
 const efi_dxe_services_table_t *efi_dxe_table;
-extern u32 image_offset;
+u32 image_offset __section(".data");
 static efi_loaded_image_t *image = NULL;
 
 static efi_status_t