[PATCH v5 2/4] efi/libstub: Reserve confidential computing secret area
From: Dov Murik <hidden>
Date: 2021-11-18 11:36:43
Also in:
linux-coco, linux-efi, lkml
Subsystem:
extensible firmware interface (efi), the rest · Maintainers:
Ard Biesheuvel, Linus Torvalds
Some older firmware declare the confidential computing secret area as EFI_BOOT_SERVICES_DATA region. Fix this up by treating this memory region as EFI_RESERVED_TYPE, as it should be. If that memory region is already EFI_RESERVED_TYPE then this has no effect on the E820 map. Signed-off-by: Dov Murik <redacted> --- drivers/firmware/efi/libstub/x86-stub.c | 28 +++++++++++++++++++++++++ 1 file changed, 28 insertions(+)
diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
index f14c4ff5839f..dabfa33ae2b3 100644
--- a/drivers/firmware/efi/libstub/x86-stub.c
+++ b/drivers/firmware/efi/libstub/x86-stub.c@@ -24,6 +24,7 @@ const efi_system_table_t *efi_system_table; extern u32 image_offset; static efi_loaded_image_t *image = NULL; +static u64 efi_coco_secret_phys_addr = U64_MAX; static efi_status_t preserve_pci_rom_image(efi_pci_io_protocol_t *pci, struct pci_setup_rom **__rom)
@@ -443,6 +444,21 @@ static void add_e820ext(struct boot_params *params, params->hdr.setup_data = (unsigned long)e820ext; } +#ifdef CONFIG_EFI_COCO_SECRET +static void efi_set_coco_secret_phys_addr(void) +{ + struct linux_efi_coco_secret_area *secret_area = + get_efi_config_table(LINUX_EFI_COCO_SECRET_AREA_GUID); + + if (!secret_area || secret_area->size == 0 || secret_area->size >= SZ_4G) + return; + + efi_coco_secret_phys_addr = secret_area->base_pa; +} +#else +static void efi_set_coco_secret_phys_addr(void) {} +#endif + static efi_status_t setup_e820(struct boot_params *params, struct setup_data *e820ext, u32 e820ext_size) {
@@ -494,6 +510,16 @@ setup_e820(struct boot_params *params, struct setup_data *e820ext, u32 e820ext_s e820_type = E820_TYPE_SOFT_RESERVED; else e820_type = E820_TYPE_RAM; +#ifdef CONFIG_EFI_COCO_SECRET + if (d->phys_addr == efi_coco_secret_phys_addr) + /* + * Fix a quirk in firmwares which don't mark + * the EFI confidential computing area as + * EFI_RESERVED_TYPE, but instead as + * EFI_BOOT_SERVICES_DATA. + */ + e820_type = E820_TYPE_RESERVED; +#endif break; case EFI_ACPI_MEMORY_NVS:
@@ -793,6 +819,8 @@ unsigned long efi_main(efi_handle_t handle, efi_retrieve_tpm2_eventlog(); + efi_set_coco_secret_phys_addr(); + setup_graphics(boot_params); setup_efi_pci(boot_params);
--
2.25.1