| Message ID | 20230518231434.26080-4-kirill.shutemov@linux.intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm, x86/cc, efi: Implement support for unaccepted memory | expand |
On 5/18/23 18:14, Kirill A. Shutemov 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> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com> > --- > 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
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