Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <20230513220418.19357-1-kirill.shutemov@linux.intel.com> <20230513220418.19357-4-kirill.shutemov@linux.intel.com>
In-Reply-To: <20230513220418.19357-4-kirill.shutemov@linux.intel.com>
From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Tue, 16 May 2023 20:06:14 +0200
Message-ID: <CAMj1kXH465Q1Y7jBPeMwbT4jz8TEEkMOnayhBMDjn=+e9DF=Kw@mail.gmail.com>
Subject: Re: [PATCHv11 3/9] efi/libstub: Implement support for unaccepted memory
To:     "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc:     Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
        Dave Hansen <dave.hansen@intel.com>,
        Sean Christopherson <seanjc@google.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Joerg Roedel <jroedel@suse.de>,
        Andi Kleen <ak@linux.intel.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        David Rientjes <rientjes@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Ingo Molnar <mingo@redhat.com>,
        Dario Faggioli <dfaggioli@suse.com>,
        Mike Rapoport <rppt@kernel.org>,
        David Hildenbrand <david@redhat.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        marcelo.cerri@canonical.com, tim.gardner@canonical.com,
        khalid.elmously@canonical.com, philip.cox@canonical.com,
        aarcange@redhat.com, peterx@redhat.com, x86@kernel.org,
        linux-mm@kvack.org, linux-coco@lists.linux.dev,
        linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

On Sun, 14 May 2023 at 00:04, Kirill A. Shutemov
<kirill.shutemov@linux.intel.com> 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@linux.intel.com>

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>

> ---
>  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
>