[RFC 07/14] efi_loader: capsule: add memory range capsule definitions

Heinrich Schuchardt
2020-03-17T08:11:43Z

On 3/17/20 3:12 AM, AKASHI Takahiro wrote:
> Memory range capsule gives us a way to notify that some memory regions
> should be left untouched across the next reset.
> See UEFI specification, section 8.5.3.

There are multiple places where RAM availability is tested by writing
during board bring up. Please, describe which changes are needed in ATF
and U-Boot to make memory range capsules work reliably.

Consider also memory encryption provided by some CPUs.
https://www.tomshardware.com/news/intel-mktme-amd-memory-encryption,39467.html

Aren't file based capsules a much more reliable way for the OS to
communicate to the firmware?

Best regards

Heinrich

>
> Since how we should handle this kind of capsule is totally up to
> the system, no implementation will be added in this commit.
>
> Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
> ---
> include/efi_api.h | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/include/efi_api.h b/include/efi_api.h
> index ac2b38801c0c..b7bf21cac7ad 100644
> --- a/include/efi_api.h
> +++ b/include/efi_api.h
> @@ -221,6 +221,10 @@ enum efi_reset_type {
> EFI_GUID(0x39b68c46, 0xf7fb, 0x441b, 0xb6, 0xec, \
> 0x16, 0xb0, 0xf6, 0x98, 0x21, 0xf3)
>
> +#define EFI_MEMORY_RANGE_CAPSULE_GUID \
> + EFI_GUID(0xde9f0ec, 0x88b6, 0x428f, 0x97, 0x7a, \
> + 0x25, 0x8f, 0x1d, 0xe, 0x5e, 0x72)
> +
> struct efi_capsule_header {
> efi_guid_t capsule_guid;
> u32 header_size;
> @@ -236,6 +240,19 @@ struct efi_capsule_result_variable_header {
> efi_status_t capsule_status;
> } __packed;
>
> +struct efi_memory_range {
> + efi_physical_addr_t address;
> + u64 length;
> +};
> +
> +struct efi_memory_range_capsule {
> + struct efi_capsule_header *header;
> + /* EFI_MEMORY_TYPE: 0x80000000-0xFFFFFFFF */
> + enum efi_mem_type os_requested_memory_type;
> + u64 number_of_memory_ranges;
> + struct efi_memory_range memory_ranges[];
> +} __packed;
> +
> #define EFI_RT_SUPPORTED_GET_TIME 0x0001
> #define EFI_RT_SUPPORTED_SET_TIME 0x0002
> #define EFI_RT_SUPPORTED_GET_WAKEUP_TIME 0x0004
>