---
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 | 234 ++++++++++++++++++
drivers/firmware/efi/libstub/x86-stub.c | 13 +
include/linux/efi.h | 12 +-
12 files changed, 377 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..fd6a3195c68f
--- /dev/null
+++ b/drivers/firmware/efi/libstub/unaccepted_memory.c
@@ -0,0 +1,234 @@
+// 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;
+
+/*
+ * Decompressor needs to initialize the variable to cover cases when the table
+ * is not allocated by EFI stub or EFI stub copied the kernel image with
+ * efi_relocate_kernel() before the variable is set.
+ *
+ * It must be call before the first usage of accept_memory() by decompressor.
+ */
+void set_unaccepted_table(struct efi_unaccepted_memory *table)
+{
+ unaccepted_table = 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
