On Sun, 14 May 2023 at 00:04, Kirill A. Shutemov
<kirill.shutemov@xxxxxxxxxxxxxxx> wrote:
>
> UEFI Specification version 2.9 introduces the concept of memory
> acceptance: Some Virtual Machine platforms, such as Intel TDX or AMD
> SEV-SNP, requiring memory to be accepted before it can be used by the
> guest. Accepting happens via a protocol specific for the Virtual
> Machine platform.
>
> Accepting memory is costly and it makes VMM allocate memory for the
> accepted guest physical address range. It's better to postpone memory
> acceptance until memory is needed. It lowers boot time and reduces
> memory overhead.
>
> The kernel needs to know what memory has been accepted. Firmware
> communicates this information via memory map: a new memory type --
> EFI_UNACCEPTED_MEMORY -- indicates such memory.
>
> Range-based tracking works fine for firmware, but it gets bulky for
> the kernel: e820 (or whatever the arch uses) has to be modified on every
> page acceptance. It leads to table fragmentation and there's a limited
> number of entries in the e820 table.
>
> Another option is to mark such memory as usable in e820 and track if the
> range has been accepted in a bitmap. One bit in the bitmap represents a
> naturally aligned power-2-sized region of address space -- unit.
>
> For x86, unit size is 2MiB: 4k of the bitmap is enough to track 64GiB or
> physical address space.
>
> In the worst-case scenario -- a huge hole in the middle of the
> address space -- It needs 256MiB to handle 4PiB of the address
> space.
>
> Any unaccepted memory that is not aligned to unit_size gets accepted
> upfront.
>
> The bitmap is allocated and constructed in the EFI stub and passed down
> to the kernel via EFI configuration table. allocate_e820() allocates the
> bitmap if unaccepted memory is present, according to the size of
> unaccepted region.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reviewed-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
> ---
> arch/x86/boot/compressed/Makefile | 1 +
> arch/x86/boot/compressed/mem.c | 9 +
> arch/x86/include/asm/efi.h | 2 +
> drivers/firmware/efi/Kconfig | 14 ++
> drivers/firmware/efi/efi.c | 1 +
> drivers/firmware/efi/libstub/Makefile | 2 +
> drivers/firmware/efi/libstub/bitmap.c | 41 ++++
> drivers/firmware/efi/libstub/efistub.h | 6 +
> drivers/firmware/efi/libstub/find.c | 43 ++++
> .../firmware/efi/libstub/unaccepted_memory.c | 222 ++++++++++++++++++
> drivers/firmware/efi/libstub/x86-stub.c | 13 +
> include/linux/efi.h | 12 +-
> 12 files changed, 365 insertions(+), 1 deletion(-)
> create mode 100644 arch/x86/boot/compressed/mem.c
> create mode 100644 drivers/firmware/efi/libstub/bitmap.c
> create mode 100644 drivers/firmware/efi/libstub/find.c
> create mode 100644 drivers/firmware/efi/libstub/unaccepted_memory.c
>
> diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
> index 6b6cfe607bdb..cc4978123c30 100644
> --- a/arch/x86/boot/compressed/Makefile
> +++ b/arch/x86/boot/compressed/Makefile
> @@ -107,6 +107,7 @@ endif
>
> vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o
> vmlinux-objs-$(CONFIG_INTEL_TDX_GUEST) += $(obj)/tdx.o $(obj)/tdcall.o
> +vmlinux-objs-$(CONFIG_UNACCEPTED_MEMORY) += $(obj)/mem.o
>
> vmlinux-objs-$(CONFIG_EFI) += $(obj)/efi.o
> vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_mixed.o
> diff --git a/arch/x86/boot/compressed/mem.c b/arch/x86/boot/compressed/mem.c
> new file mode 100644
> index 000000000000..67594fcb11d9
> --- /dev/null
> +++ b/arch/x86/boot/compressed/mem.c
> @@ -0,0 +1,9 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include "error.h"
> +
> +void arch_accept_memory(phys_addr_t start, phys_addr_t end)
> +{
> + /* Platform-specific memory-acceptance call goes here */
> + error("Cannot accept memory");
> +}
> diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
> index 419280d263d2..8b4be7cecdb8 100644
> --- a/arch/x86/include/asm/efi.h
> +++ b/arch/x86/include/asm/efi.h
> @@ -31,6 +31,8 @@ extern unsigned long efi_mixed_mode_stack_pa;
>
> #define ARCH_EFI_IRQ_FLAGS_MASK X86_EFLAGS_IF
>
> +#define EFI_UNACCEPTED_UNIT_SIZE PMD_SIZE
> +
> /*
> * The EFI services are called through variadic functions in many cases. These
> * functions are implemented in assembler and support only a fixed number of
> diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
> index 043ca31c114e..231f1c70d1db 100644
> --- a/drivers/firmware/efi/Kconfig
> +++ b/drivers/firmware/efi/Kconfig
> @@ -269,6 +269,20 @@ config EFI_COCO_SECRET
> virt/coco/efi_secret module to access the secrets, which in turn
> allows userspace programs to access the injected secrets.
>
> +config UNACCEPTED_MEMORY
> + bool
> + depends on EFI_STUB
> + help
> + Some Virtual Machine platforms, such as Intel TDX, require
> + some memory to be "accepted" by the guest before it can be used.
> + This mechanism helps prevent malicious hosts from making changes
> + to guest memory.
> +
> + UEFI specification v2.9 introduced EFI_UNACCEPTED_MEMORY memory type.
> +
> + This option adds support for unaccepted memory and makes such memory
> + usable by the kernel.
> +
> config EFI_EMBEDDED_FIRMWARE
> bool
> select CRYPTO_LIB_SHA256
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index abeff7dc0b58..7dce06e419c5 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -843,6 +843,7 @@ static __initdata char memory_type_name[][13] = {
> "MMIO Port",
> "PAL Code",
> "Persistent",
> + "Unaccepted",
> };
>
> char * __init efi_md_typeattr_format(char *buf, size_t size,
> diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> index 3abb2b357482..16d64a34d1e1 100644
> --- a/drivers/firmware/efi/libstub/Makefile
> +++ b/drivers/firmware/efi/libstub/Makefile
> @@ -96,6 +96,8 @@ CFLAGS_arm32-stub.o := -DTEXT_OFFSET=$(TEXT_OFFSET)
> zboot-obj-$(CONFIG_RISCV) := lib-clz_ctz.o lib-ashldi3.o
> lib-$(CONFIG_EFI_ZBOOT) += zboot.o $(zboot-obj-y)
>
> +lib-$(CONFIG_UNACCEPTED_MEMORY) += unaccepted_memory.o bitmap.o find.o
> +
> extra-y := $(lib-y)
> lib-y := $(patsubst %.o,%.stub.o,$(lib-y))
>
> diff --git a/drivers/firmware/efi/libstub/bitmap.c b/drivers/firmware/efi/libstub/bitmap.c
> new file mode 100644
> index 000000000000..5c9bba0d549b
> --- /dev/null
> +++ b/drivers/firmware/efi/libstub/bitmap.c
> @@ -0,0 +1,41 @@
> +#include <linux/bitmap.h>
> +
> +void __bitmap_set(unsigned long *map, unsigned int start, int len)
> +{
> + unsigned long *p = map + BIT_WORD(start);
> + const unsigned int size = start + len;
> + int bits_to_set = BITS_PER_LONG - (start % BITS_PER_LONG);
> + unsigned long mask_to_set = BITMAP_FIRST_WORD_MASK(start);
> +
> + while (len - bits_to_set >= 0) {
> + *p |= mask_to_set;
> + len -= bits_to_set;
> + bits_to_set = BITS_PER_LONG;
> + mask_to_set = ~0UL;
> + p++;
> + }
> + if (len) {
> + mask_to_set &= BITMAP_LAST_WORD_MASK(size);
> + *p |= mask_to_set;
> + }
> +}
> +
> +void __bitmap_clear(unsigned long *map, unsigned int start, int len)
> +{
> + unsigned long *p = map + BIT_WORD(start);
> + const unsigned int size = start + len;
> + int bits_to_clear = BITS_PER_LONG - (start % BITS_PER_LONG);
> + unsigned long mask_to_clear = BITMAP_FIRST_WORD_MASK(start);
> +
> + while (len - bits_to_clear >= 0) {
> + *p &= ~mask_to_clear;
> + len -= bits_to_clear;
> + bits_to_clear = BITS_PER_LONG;
> + mask_to_clear = ~0UL;
> + p++;
> + }
> + if (len) {
> + mask_to_clear &= BITMAP_LAST_WORD_MASK(size);
> + *p &= ~mask_to_clear;
> + }
> +}
> diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
> index 67d5a20802e0..8659a01664b8 100644
> --- a/drivers/firmware/efi/libstub/efistub.h
> +++ b/drivers/firmware/efi/libstub/efistub.h
> @@ -1133,4 +1133,10 @@ const u8 *__efi_get_smbios_string(const struct efi_smbios_record *record,
> void efi_remap_image(unsigned long image_base, unsigned alloc_size,
> unsigned long code_size);
>
> +efi_status_t allocate_unaccepted_bitmap(__u32 nr_desc,
> + struct efi_boot_memmap *map);
> +void process_unaccepted_memory(u64 start, u64 end);
> +void accept_memory(phys_addr_t start, phys_addr_t end);
> +void arch_accept_memory(phys_addr_t start, phys_addr_t end);
> +
> #endif
> diff --git a/drivers/firmware/efi/libstub/find.c b/drivers/firmware/efi/libstub/find.c
> new file mode 100644
> index 000000000000..4e7740d28987
> --- /dev/null
> +++ b/drivers/firmware/efi/libstub/find.c
> @@ -0,0 +1,43 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +#include <linux/bitmap.h>
> +#include <linux/math.h>
> +#include <linux/minmax.h>
> +
> +/*
> + * Common helper for find_next_bit() function family
> + * @FETCH: The expression that fetches and pre-processes each word of bitmap(s)
> + * @MUNGE: The expression that post-processes a word containing found bit (may be empty)
> + * @size: The bitmap size in bits
> + * @start: The bitnumber to start searching at
> + */
> +#define FIND_NEXT_BIT(FETCH, MUNGE, size, start) \
> +({ \
> + unsigned long mask, idx, tmp, sz = (size), __start = (start); \
> + \
> + if (unlikely(__start >= sz)) \
> + goto out; \
> + \
> + mask = MUNGE(BITMAP_FIRST_WORD_MASK(__start)); \
> + idx = __start / BITS_PER_LONG; \
> + \
> + for (tmp = (FETCH) & mask; !tmp; tmp = (FETCH)) { \
> + if ((idx + 1) * BITS_PER_LONG >= sz) \
> + goto out; \
> + idx++; \
> + } \
> + \
> + sz = min(idx * BITS_PER_LONG + __ffs(MUNGE(tmp)), sz); \
> +out: \
> + sz; \
> +})
> +
> +unsigned long _find_next_bit(const unsigned long *addr, unsigned long nbits, unsigned long start)
> +{
> + return FIND_NEXT_BIT(addr[idx], /* nop */, nbits, start);
> +}
> +
> +unsigned long _find_next_zero_bit(const unsigned long *addr, unsigned long nbits,
> + unsigned long start)
> +{
> + return FIND_NEXT_BIT(~addr[idx], /* nop */, nbits, start);
> +}
> diff --git a/drivers/firmware/efi/libstub/unaccepted_memory.c b/drivers/firmware/efi/libstub/unaccepted_memory.c
> new file mode 100644
> index 000000000000..f4642c4f25dd
> --- /dev/null
> +++ b/drivers/firmware/efi/libstub/unaccepted_memory.c
> @@ -0,0 +1,222 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <linux/efi.h>
> +#include <asm/efi.h>
> +#include "efistub.h"
> +
> +static struct efi_unaccepted_memory *unaccepted_table;
> +
> +efi_status_t allocate_unaccepted_bitmap(__u32 nr_desc,
> + struct efi_boot_memmap *map)
> +{
> + efi_guid_t unaccepted_table_guid = LINUX_EFI_UNACCEPTED_MEM_TABLE_GUID;
> + u64 unaccepted_start = ULLONG_MAX, unaccepted_end = 0, bitmap_size;
> + efi_status_t status;
> + int i;
> +
> + /* Check if the table is already installed */
> + unaccepted_table = get_efi_config_table(unaccepted_table_guid);
> + if (unaccepted_table) {
> + if (unaccepted_table->version != 1) {
> + efi_err("Unknown version of unaccepted memory table\n");
> + return EFI_UNSUPPORTED;
> + }
> + return EFI_SUCCESS;
> + }
> +
> + /* Check if there's any unaccepted memory and find the max address */
> + for (i = 0; i < nr_desc; i++) {
> + efi_memory_desc_t *d;
> + unsigned long m = (unsigned long)map->map;
> +
> + d = efi_early_memdesc_ptr(m, map->desc_size, i);
> + if (d->type != EFI_UNACCEPTED_MEMORY)
> + continue;
> +
> + unaccepted_start = min(unaccepted_start, d->phys_addr);
> + unaccepted_end = max(unaccepted_end,
> + d->phys_addr + d->num_pages * PAGE_SIZE);
> + }
> +
> + if (unaccepted_start == ULLONG_MAX)
> + return EFI_SUCCESS;
> +
> + unaccepted_start = round_down(unaccepted_start,
> + EFI_UNACCEPTED_UNIT_SIZE);
> + unaccepted_end = round_up(unaccepted_end, EFI_UNACCEPTED_UNIT_SIZE);
> +
> + /*
> + * If unaccepted memory is present, allocate a bitmap to track what
> + * memory has to be accepted before access.
> + *
> + * One bit in the bitmap represents 2MiB in the address space:
> + * A 4k bitmap can track 64GiB of physical address space.
> + *
> + * In the worst case scenario -- a huge hole in the middle of the
> + * address space -- It needs 256MiB to handle 4PiB of the address
> + * space.
> + *
> + * The bitmap will be populated in setup_e820() according to the memory
> + * map after efi_exit_boot_services().
> + */
> + bitmap_size = DIV_ROUND_UP(unaccepted_end - unaccepted_start,
> + EFI_UNACCEPTED_UNIT_SIZE * BITS_PER_BYTE);
> +
> + status = efi_bs_call(allocate_pool, EFI_LOADER_DATA,
> + sizeof(*unaccepted_table) + bitmap_size,
> + (void **)&unaccepted_table);
> + if (status != EFI_SUCCESS) {
> + efi_err("Failed to allocate unaccepted memory config table\n");
> + return status;
> + }
> +
> + unaccepted_table->version = 1;
> + unaccepted_table->unit_size = EFI_UNACCEPTED_UNIT_SIZE;
> + unaccepted_table->phys_base = unaccepted_start;
> + unaccepted_table->size = bitmap_size;
> + memset(unaccepted_table->bitmap, 0, bitmap_size);
> +
> + status = efi_bs_call(install_configuration_table,
> + &unaccepted_table_guid, unaccepted_table);
> + if (status != EFI_SUCCESS) {
> + efi_bs_call(free_pool, unaccepted_table);
> + efi_err("Failed to install unaccepted memory config table!\n");
> + }
> +
> + return status;
> +}
> +
> +/*
> + * The accepted memory bitmap only works at unit_size granularity. Take
> + * unaligned start/end addresses and either:
> + * 1. Accepts the memory immediately and in its entirety
> + * 2. Accepts unaligned parts, and marks *some* aligned part unaccepted
> + *
> + * The function will never reach the bitmap_set() with zero bits to set.
> + */
> +void process_unaccepted_memory(u64 start, u64 end)
> +{
> + u64 unit_size = unaccepted_table->unit_size;
> + u64 unit_mask = unaccepted_table->unit_size - 1;
> + u64 bitmap_size = unaccepted_table->size;
> +
> + /*
> + * Ensure that at least one bit will be set in the bitmap by
> + * immediately accepting all regions under 2*unit_size. This is
> + * imprecise and may immediately accept some areas that could
> + * have been represented in the bitmap. But, results in simpler
> + * code below
> + *
> + * Consider case like this (assuming unit_size == 2MB):
> + *
> + * | 4k | 2044k | 2048k |
> + * ^ 0x0 ^ 2MB ^ 4MB
> + *
> + * Only the first 4k has been accepted. The 0MB->2MB region can not be
> + * represented in the bitmap. The 2MB->4MB region can be represented in
> + * the bitmap. But, the 0MB->4MB region is <2*unit_size and will be
> + * immediately accepted in its entirety.
> + */
> + if (end - start < 2 * unit_size) {
> + arch_accept_memory(start, end);
> + return;
> + }
> +
> + /*
> + * No matter how the start and end are aligned, at least one unaccepted
> + * unit_size area will remain to be marked in the bitmap.
> + */
> +
> + /* Immediately accept a <unit_size piece at the start: */
> + if (start & unit_mask) {
> + arch_accept_memory(start, round_up(start, unit_size));
> + start = round_up(start, unit_size);
> + }
> +
> + /* Immediately accept a <unit_size piece at the end: */
> + if (end & unit_mask) {
> + arch_accept_memory(round_down(end, unit_size), end);
> + end = round_down(end, unit_size);
> + }
> +
> + /*
> + * Accept part of the range that before phys_base and cannot be recorded
> + * into the bitmap.
> + */
> + if (start < unaccepted_table->phys_base) {
> + arch_accept_memory(start,
> + min(unaccepted_table->phys_base, end));
> + start = unaccepted_table->phys_base;
> + }
> +
> + /* Nothing to record */
> + if (end < unaccepted_table->phys_base)
> + return;
> +
> + /* Translate to offsets from the beginning of the bitmap */
> + start -= unaccepted_table->phys_base;
> + end -= unaccepted_table->phys_base;
> +
> + /* Accept memory that doesn't fit into bitmap */
> + if (end > bitmap_size * unit_size * BITS_PER_BYTE) {
> + unsigned long phys_start, phys_end;
> +
> + phys_start = bitmap_size * unit_size * BITS_PER_BYTE +
> + unaccepted_table->phys_base;
> + phys_end = end + unaccepted_table->phys_base;
> +
> + arch_accept_memory(phys_start, phys_end);
> + end = bitmap_size * unit_size * BITS_PER_BYTE;
> + }
> +
> + /*
> + * 'start' and 'end' are now both unit_size-aligned.
> + * Record the range as being unaccepted:
> + */
> + bitmap_set(unaccepted_table->bitmap,
> + start / unit_size, (end - start) / unit_size);
> +}
> +
> +void accept_memory(phys_addr_t start, phys_addr_t end)
> +{
> + unsigned long range_start, range_end;
> + unsigned long bitmap_size;
> + u64 unit_size;
> +
> + if (!unaccepted_table)
> + return;
> +
> + unit_size = unaccepted_table->unit_size;
> +
> + /*
> + * Only care for the part of the range that is represented
> + * in the bitmap.
> + */
> + if (start < unaccepted_table->phys_base)
> + start = unaccepted_table->phys_base;
> + if (end < unaccepted_table->phys_base)
> + return;
> +
> + /* Translate to offsets from the beginning of the bitmap */
> + start -= unaccepted_table->phys_base;
> + end -= unaccepted_table->phys_base;
> +
> + /* Make sure not to overrun the bitmap */
> + if (end > unaccepted_table->size * unit_size * BITS_PER_BYTE)
> + end = unaccepted_table->size * unit_size * BITS_PER_BYTE;
> +
> + range_start = start / unit_size;
> + bitmap_size = DIV_ROUND_UP(end, unit_size);
> +
> + for_each_set_bitrange_from(range_start, range_end,
> + unaccepted_table->bitmap, bitmap_size) {
> + unsigned long phys_start, phys_end;
> +
> + phys_start = range_start * unit_size + unaccepted_table->phys_base;
> + phys_end = range_end * unit_size + unaccepted_table->phys_base;
> +
> + arch_accept_memory(phys_start, phys_end);
> + bitmap_clear(unaccepted_table->bitmap,
> + range_start, range_end - range_start);
> + }
> +}
> diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
> index fff81843169c..8d17cee8b98e 100644
> --- a/drivers/firmware/efi/libstub/x86-stub.c
> +++ b/drivers/firmware/efi/libstub/x86-stub.c
> @@ -613,6 +613,16 @@ setup_e820(struct boot_params *params, struct setup_data *e820ext, u32 e820ext_s
> e820_type = E820_TYPE_PMEM;
> break;
>
> + case EFI_UNACCEPTED_MEMORY:
> + if (!IS_ENABLED(CONFIG_UNACCEPTED_MEMORY)) {
> + efi_warn_once(
> +"The system has unaccepted memory, but kernel does not support it\nConsider enabling CONFIG_UNACCEPTED_MEMORY\n");
> + continue;
> + }
> + e820_type = E820_TYPE_RAM;
> + process_unaccepted_memory(d->phys_addr,
> + d->phys_addr + PAGE_SIZE * d->num_pages);
> + break;
> default:
> continue;
> }
> @@ -697,6 +707,9 @@ static efi_status_t allocate_e820(struct boot_params *params,
> status = alloc_e820ext(nr_e820ext, e820ext, e820ext_size);
> }
>
> + if (IS_ENABLED(CONFIG_UNACCEPTED_MEMORY) && status == EFI_SUCCESS)
> + status = allocate_unaccepted_bitmap(nr_desc, map);
> +
> efi_bs_call(free_pool, map);
> return status;
> }
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index 7aa62c92185f..29cc622910da 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -108,7 +108,8 @@ typedef struct {
> #define EFI_MEMORY_MAPPED_IO_PORT_SPACE 12
> #define EFI_PAL_CODE 13
> #define EFI_PERSISTENT_MEMORY 14
> -#define EFI_MAX_MEMORY_TYPE 15
> +#define EFI_UNACCEPTED_MEMORY 15
> +#define EFI_MAX_MEMORY_TYPE 16
>
> /* Attribute values: */
> #define EFI_MEMORY_UC ((u64)0x0000000000000001ULL) /* uncached */
> @@ -417,6 +418,7 @@ void efi_native_runtime_setup(void);
> #define LINUX_EFI_MOK_VARIABLE_TABLE_GUID EFI_GUID(0xc451ed2b, 0x9694, 0x45d3, 0xba, 0xba, 0xed, 0x9f, 0x89, 0x88, 0xa3, 0x89)
> #define LINUX_EFI_COCO_SECRET_AREA_GUID EFI_GUID(0xadf956ad, 0xe98c, 0x484c, 0xae, 0x11, 0xb5, 0x1c, 0x7d, 0x33, 0x64, 0x47)
> #define LINUX_EFI_BOOT_MEMMAP_GUID EFI_GUID(0x800f683f, 0xd08b, 0x423a, 0xa2, 0x93, 0x96, 0x5c, 0x3c, 0x6f, 0xe2, 0xb4)
> +#define LINUX_EFI_UNACCEPTED_MEM_TABLE_GUID EFI_GUID(0xd5d1de3c, 0x105c, 0x44f9, 0x9e, 0xa9, 0xbc, 0xef, 0x98, 0x12, 0x00, 0x31)
>
> #define RISCV_EFI_BOOT_PROTOCOL_GUID EFI_GUID(0xccd15fec, 0x6f73, 0x4eec, 0x83, 0x95, 0x3e, 0x69, 0xe4, 0xb9, 0x40, 0xbf)
>
> @@ -534,6 +536,14 @@ struct efi_boot_memmap {
> efi_memory_desc_t map[];
> };
>
> +struct efi_unaccepted_memory {
> + u32 version;
> + u32 unit_size;
> + u64 phys_base;
> + u64 size;
> + unsigned long bitmap[];
> +};
> +
> /*
> * Architecture independent structure for describing a memory map for the
> * benefit of efi_memmap_init_early(), and for passing context between
> --
> 2.39.3
>
