efi: memmap: Move EFI fake memmap support into x86 arch tree

The EFI fake memmap support is specific to x86, which manipulates the
EFI memory map in various different ways after receiving it from the EFI
stub. On other architectures, we have managed to push back on this, and
the EFI memory map is kept pristine.

So let's move the fake memmap code into the x86 arch tree, where it
arguably belongs.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

arch/x86/Kconfig

@@ -1994,6 +1994,26 @@ config EFI_MIXED
 
 	  If unsure, say N.
 
+config EFI_FAKE_MEMMAP
+	bool "Enable EFI fake memory map"
+	depends on EFI
+	help
+	  Saying Y here will enable "efi_fake_mem" boot option.  By specifying
+	  this parameter, you can add arbitrary attribute to specific memory
+	  range by updating original (firmware provided) EFI memmap.  This is
+	  useful for debugging of EFI memmap related feature, e.g., Address
+	  Range Mirroring feature.
+
+config EFI_MAX_FAKE_MEM
+	int "maximum allowable number of ranges in efi_fake_mem boot option"
+	depends on EFI_FAKE_MEMMAP
+	range 1 128
+	default 8
+	help
+	  Maximum allowable number of ranges in efi_fake_mem boot option.
+	  Ranges can be set up to this value using comma-separated list.
+	  The default value is 8.
+
 source "kernel/Kconfig.hz"
 
 config KEXEC

arch/x86/include/asm/efi.h

@@ -406,10 +406,15 @@ static inline void efi_reserve_boot_services(void)
 
 #ifdef CONFIG_EFI_FAKE_MEMMAP
 extern void __init efi_fake_memmap_early(void);
+extern void __init efi_fake_memmap(void);
 #else
 static inline void efi_fake_memmap_early(void)
 {
 }
+
+static inline void efi_fake_memmap(void)
+{
+}
 #endif
 
 #define arch_ima_efi_boot_mode	\

arch/x86/kernel/setup.c

@@ -31,6 +31,7 @@
 #include <xen/xen.h>
 
 #include <asm/apic.h>
+#include <asm/efi.h>
 #include <asm/numa.h>
 #include <asm/bios_ebda.h>
 #include <asm/bugs.h>

arch/x86/platform/efi/Makefile

@@ -4,3 +4,4 @@ GCOV_PROFILE := n
 
 obj-$(CONFIG_EFI) 		+= quirks.o efi.o efi_$(BITS).o efi_stub_$(BITS).o
 obj-$(CONFIG_EFI_MIXED)		+= efi_thunk_$(BITS).o
+obj-$(CONFIG_EFI_FAKE_MEMMAP)	+= fake_mem.o

drivers/firmware/efi/fake_mem.c → arch/x86/platform/efi/fake_mem.c

@@ -17,10 +17,13 @@
 #include <linux/memblock.h>
 #include <linux/types.h>
 #include <linux/sort.h>
-#include "fake_mem.h"
+#include <asm/e820/api.h>
+#include <asm/efi.h>
 
-struct efi_mem_range efi_fake_mems[EFI_MAX_FAKEMEM];
-int nr_fake_mem;
+#define EFI_MAX_FAKEMEM CONFIG_EFI_MAX_FAKE_MEM
+
+static struct efi_mem_range efi_fake_mems[EFI_MAX_FAKEMEM];
+static int nr_fake_mem;
 
 static int __init cmp_fake_mem(const void *x1, const void *x2)
 {
@@ -122,3 +125,73 @@ static int __init setup_fake_mem(char *p)
 }
 
 early_param("efi_fake_mem", setup_fake_mem);
+
+void __init efi_fake_memmap_early(void)
+{
+	int i;
+
+	/*
+	 * The late efi_fake_mem() call can handle all requests if
+	 * EFI_MEMORY_SP support is disabled.
+	 */
+	if (!efi_soft_reserve_enabled())
+		return;
+
+	if (!efi_enabled(EFI_MEMMAP) || !nr_fake_mem)
+		return;
+
+	/*
+	 * Given that efi_fake_memmap() needs to perform memblock
+	 * allocations it needs to run after e820__memblock_setup().
+	 * However, if efi_fake_mem specifies EFI_MEMORY_SP for a given
+	 * address range that potentially needs to mark the memory as
+	 * reserved prior to e820__memblock_setup(). Update e820
+	 * directly if EFI_MEMORY_SP is specified for an
+	 * EFI_CONVENTIONAL_MEMORY descriptor.
+	 */
+	for (i = 0; i < nr_fake_mem; i++) {
+		struct efi_mem_range *mem = &efi_fake_mems[i];
+		efi_memory_desc_t *md;
+		u64 m_start, m_end;
+
+		if ((mem->attribute & EFI_MEMORY_SP) == 0)
+			continue;
+
+		m_start = mem->range.start;
+		m_end = mem->range.end;
+		for_each_efi_memory_desc(md) {
+			u64 start, end, size;
+
+			if (md->type != EFI_CONVENTIONAL_MEMORY)
+				continue;
+
+			start = md->phys_addr;
+			end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1;
+
+			if (m_start <= end && m_end >= start)
+				/* fake range overlaps descriptor */;
+			else
+				continue;
+
+			/*
+			 * Trim the boundary of the e820 update to the
+			 * descriptor in case the fake range overlaps
+			 * !EFI_CONVENTIONAL_MEMORY
+			 */
+			start = max(start, m_start);
+			end = min(end, m_end);
+			size = end - start + 1;
+
+			if (end <= start)
+				continue;
+
+			/*
+			 * Ensure each efi_fake_mem instance results in
+			 * a unique e820 resource
+			 */
+			e820__range_remove(start, size, E820_TYPE_RAM, 1);
+			e820__range_add(start, size, E820_TYPE_SOFT_RESERVED);
+			e820__update_table(e820_table);
+		}
+	}
+}

drivers/firmware/efi/Kconfig

@@ -37,28 +37,6 @@ config EFI_RUNTIME_MAP
 
 	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
 
-config EFI_FAKE_MEMMAP
-	bool "Enable EFI fake memory map"
-	depends on EFI && X86
-	default n
-	help
-	  Saying Y here will enable "efi_fake_mem" boot option.
-	  By specifying this parameter, you can add arbitrary attribute
-	  to specific memory range by updating original (firmware provided)
-	  EFI memmap.
-	  This is useful for debugging of EFI memmap related feature.
-	  e.g. Address Range Mirroring feature.
-
-config EFI_MAX_FAKE_MEM
-	int "maximum allowable number of ranges in efi_fake_mem boot option"
-	depends on EFI_FAKE_MEMMAP
-	range 1 128
-	default 8
-	help
-	  Maximum allowable number of ranges in efi_fake_mem boot option.
-	  Ranges can be set up to this value using comma-separated list.
-	  The default value is 8.
-
 config EFI_SOFT_RESERVE
 	bool "Reserve EFI Specific Purpose Memory"
 	depends on EFI && EFI_STUB && ACPI_HMAT

drivers/firmware/efi/Makefile

@@ -23,7 +23,6 @@ obj-$(CONFIG_UEFI_CPER)			+= cper.o
 obj-$(CONFIG_EFI_RUNTIME_MAP)		+= runtime-map.o
 obj-$(CONFIG_EFI_RUNTIME_WRAPPERS)	+= runtime-wrappers.o
 subdir-$(CONFIG_EFI_STUB)		+= libstub
-obj-$(CONFIG_EFI_FAKE_MEMMAP)		+= fake_map.o
 obj-$(CONFIG_EFI_BOOTLOADER_CONTROL)	+= efibc.o
 obj-$(CONFIG_EFI_TEST)			+= test/
 obj-$(CONFIG_EFI_DEV_PATH_PARSER)	+= dev-path-parser.o
@@ -32,9 +31,6 @@ obj-$(CONFIG_EFI_RCI2_TABLE)		+= rci2-table.o
 obj-$(CONFIG_EFI_EMBEDDED_FIRMWARE)	+= embedded-firmware.o
 obj-$(CONFIG_LOAD_UEFI_KEYS)		+= mokvar-table.o
 
-fake_map-y				+= fake_mem.o
-fake_map-$(CONFIG_X86)			+= x86_fake_mem.o
-
 obj-$(CONFIG_SYSFB)			+= sysfb_efi.o
 
 arm-obj-$(CONFIG_EFI)			:= efi-init.o arm-runtime.o

drivers/firmware/efi/fake_mem.h

-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __EFI_FAKE_MEM_H__
-#define __EFI_FAKE_MEM_H__
-#include <asm/efi.h>
-
-#define EFI_MAX_FAKEMEM CONFIG_EFI_MAX_FAKE_MEM
-
-extern struct efi_mem_range efi_fake_mems[EFI_MAX_FAKEMEM];
-extern int nr_fake_mem;
-#endif /* __EFI_FAKE_MEM_H__ */

drivers/firmware/efi/x86_fake_mem.c

-// SPDX-License-Identifier: GPL-2.0
-/* Copyright(c) 2019 Intel Corporation. All rights reserved. */
-#include <linux/efi.h>
-#include <asm/e820/api.h>
-#include "fake_mem.h"
-
-void __init efi_fake_memmap_early(void)
-{
-	int i;
-
-	/*
-	 * The late efi_fake_mem() call can handle all requests if
-	 * EFI_MEMORY_SP support is disabled.
-	 */
-	if (!efi_soft_reserve_enabled())
-		return;
-
-	if (!efi_enabled(EFI_MEMMAP) || !nr_fake_mem)
-		return;
-
-	/*
-	 * Given that efi_fake_memmap() needs to perform memblock
-	 * allocations it needs to run after e820__memblock_setup().
-	 * However, if efi_fake_mem specifies EFI_MEMORY_SP for a given
-	 * address range that potentially needs to mark the memory as
-	 * reserved prior to e820__memblock_setup(). Update e820
-	 * directly if EFI_MEMORY_SP is specified for an
-	 * EFI_CONVENTIONAL_MEMORY descriptor.
-	 */
-	for (i = 0; i < nr_fake_mem; i++) {
-		struct efi_mem_range *mem = &efi_fake_mems[i];
-		efi_memory_desc_t *md;
-		u64 m_start, m_end;
-
-		if ((mem->attribute & EFI_MEMORY_SP) == 0)
-			continue;
-
-		m_start = mem->range.start;
-		m_end = mem->range.end;
-		for_each_efi_memory_desc(md) {
-			u64 start, end, size;
-
-			if (md->type != EFI_CONVENTIONAL_MEMORY)
-				continue;
-
-			start = md->phys_addr;
-			end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1;
-
-			if (m_start <= end && m_end >= start)
-				/* fake range overlaps descriptor */;
-			else
-				continue;
-
-			/*
-			 * Trim the boundary of the e820 update to the
-			 * descriptor in case the fake range overlaps
-			 * !EFI_CONVENTIONAL_MEMORY
-			 */
-			start = max(start, m_start);
-			end = min(end, m_end);
-			size = end - start + 1;
-
-			if (end <= start)
-				continue;
-
-			/*
-			 * Ensure each efi_fake_mem instance results in
-			 * a unique e820 resource
-			 */
-			e820__range_remove(start, size, E820_TYPE_RAM, 1);
-			e820__range_add(start, size, E820_TYPE_SOFT_RESERVED);
-			e820__update_table(e820_table);
-		}
-	}
-}

include/linux/efi.h

@@ -749,12 +749,6 @@ extern struct kobject *efi_kobj;
 extern int efi_reboot_quirk_mode;
 extern bool efi_poweroff_required(void);
 
-#ifdef CONFIG_EFI_FAKE_MEMMAP
-extern void __init efi_fake_memmap(void);
-#else
-static inline void efi_fake_memmap(void) { }
-#endif
-
 extern unsigned long efi_mem_attr_table;
 
 /*