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| author | Dov Murik <dovmurik@linux.ibm.com> | 2022-04-13 00:21:24 +0300 |
|---|---|---|
| committer | Ard Biesheuvel <ardb@kernel.org> | 2022-04-13 20:11:18 +0300 |
| commit | 1227418989346af3af179742cf42ce842e0ad484 (patch) | |
| tree | 36f02d45fc9b95f624bf93d59d45cb515daeecd5 /drivers/firmware/efi | |
| parent | a031651ff2144a3d81d4916856c093bc1ea0a413 (diff) | |
| download | linux-1227418989346af3af179742cf42ce842e0ad484.tar.xz | |
efi: Save location of EFI confidential computing area
Confidential computing (coco) hardware such as AMD SEV (Secure Encrypted
Virtualization) allows a guest owner to inject secrets into the VMs
memory without the host/hypervisor being able to read them.
Firmware support for secret injection is available in OVMF, which
reserves a memory area for secret injection and includes a pointer to it
the in EFI config table entry LINUX_EFI_COCO_SECRET_TABLE_GUID.
If EFI exposes such a table entry, uefi_init() will keep a pointer to
the EFI config table entry in efi.coco_secret, so it can be used later
by the kernel (specifically drivers/virt/coco/efi_secret). It will also
appear in the kernel log as "CocoSecret=ADDRESS"; for example:
[ 0.000000] efi: EFI v2.70 by EDK II
[ 0.000000] efi: CocoSecret=0x7f22e680 SMBIOS=0x7f541000 ACPI=0x7f77e000 ACPI 2.0=0x7f77e014 MEMATTR=0x7ea0c018
The new functionality can be enabled with CONFIG_EFI_COCO_SECRET=y.
Signed-off-by: Dov Murik <dovmurik@linux.ibm.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
Link: https://lore.kernel.org/r/20220412212127.154182-2-dovmurik@linux.ibm.com
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Diffstat (limited to 'drivers/firmware/efi')
| -rw-r--r-- | drivers/firmware/efi/Kconfig | 16 | ||||
| -rw-r--r-- | drivers/firmware/efi/efi.c | 6 |
2 files changed, 22 insertions, 0 deletions
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig index 243882f5e5f9..f8ddd2259ba0 100644 --- a/drivers/firmware/efi/Kconfig +++ b/drivers/firmware/efi/Kconfig @@ -299,3 +299,19 @@ config EFI_DISABLE_RUNTIME an issue for Real-Time kernels. This default can be overridden by using the efi=runtime option. + +config EFI_COCO_SECRET + bool "EFI Confidential Computing Secret Area Support" + depends on EFI + help + Confidential Computing platforms (such as AMD SEV) allow the + Guest Owner to securely inject secrets during guest VM launch. + The secrets are placed in a designated EFI reserved memory area. + + In order to use the secrets in the kernel, the location of the secret + area (as published in the EFI config table) must be kept. + + If you say Y here, the address of the EFI secret area will be kept + for usage inside the kernel. This will allow the + virt/coco/efi_secret module to access the secrets, which in turn + allows userspace programs to access the injected secrets. diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index ff57db8f8d05..e0f43262d451 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -46,6 +46,9 @@ struct efi __read_mostly efi = { #ifdef CONFIG_LOAD_UEFI_KEYS .mokvar_table = EFI_INVALID_TABLE_ADDR, #endif +#ifdef CONFIG_EFI_COCO_SECRET + .coco_secret = EFI_INVALID_TABLE_ADDR, +#endif }; EXPORT_SYMBOL(efi); @@ -529,6 +532,9 @@ static const efi_config_table_type_t common_tables[] __initconst = { #ifdef CONFIG_LOAD_UEFI_KEYS {LINUX_EFI_MOK_VARIABLE_TABLE_GUID, &efi.mokvar_table, "MOKvar" }, #endif +#ifdef CONFIG_EFI_COCO_SECRET + {LINUX_EFI_COCO_SECRET_AREA_GUID, &efi.coco_secret, "CocoSecret" }, +#endif {}, }; |