bc744f5893
SMMSTORE version 2 is a complete redesign of the current driver. It is
not backwards-compatible with version 1, and only one version can be
used at a time.
Key features:
* Uses a fixed communication buffer instead of writing to arbitrary
memory addresses provided by untrusted ring0 code.
* Gives the caller full control over the used data format.
* Splits the store into smaller chunks to allow fault tolerant updates.
* Doesn't provide feedback about the actual read/written bytes, just
returns error or success in registers.
* Returns an error if the requested operation would overflow the
communication buffer.
Separate the SMMSTORE into 64 KiB blocks that can individually be
read/written/erased. To be used by payloads that implement a
FaultTolerant Variable store like TianoCore.
The implementation has been tested against EDK2 master.
An example EDK2 implementation can be found here:
eb1127744a
Change-Id: I25e49d184135710f3e6dd1ad3bed95de950fe057
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Signed-off-by: Christian Walter <christian.walter@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/40520
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Michał Żygowski <michal.zygowski@3mdeb.com>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>
123 lines
3 KiB
C
123 lines
3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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#ifndef _SMMSTORE_H_
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#define _SMMSTORE_H_
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#include <stddef.h>
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#include <stdint.h>
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#define SMMSTORE_RET_SUCCESS 0
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#define SMMSTORE_RET_FAILURE 1
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#define SMMSTORE_RET_UNSUPPORTED 2
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/* Version 1 */
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#define SMMSTORE_CMD_CLEAR 1
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#define SMMSTORE_CMD_READ 2
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#define SMMSTORE_CMD_APPEND 3
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/* Version 2 */
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#define SMMSTORE_CMD_INIT 4
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#define SMMSTORE_CMD_RAW_READ 5
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#define SMMSTORE_CMD_RAW_WRITE 6
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#define SMMSTORE_CMD_RAW_CLEAR 7
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/* Version 1 */
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struct smmstore_params_read {
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void *buf;
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ssize_t bufsize;
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};
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struct smmstore_params_append {
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void *key;
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size_t keysize;
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void *val;
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size_t valsize;
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};
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/* Version 2 */
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/*
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* The Version 2 protocol separates the SMMSTORE into 64KiB blocks, each
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* of which can be read/written/cleared in an independent manner. The
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* data format isn't specified. See documentation page for more details.
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*/
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#define SMM_BLOCK_SIZE (64 * KiB)
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/*
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* Sets the communication buffer to use for read and write operations.
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*/
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struct smmstore_params_init {
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uint32_t com_buffer;
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uint32_t com_buffer_size;
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} __packed;
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/*
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* Returns the number of blocks the SMMSTORE supports and their size.
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* For EDK2 this should be at least two blocks with 64 KiB each.
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* The mmap_addr is set the memory mapped physical address of the SMMSTORE.
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*/
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struct smmstore_params_info {
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uint32_t num_blocks;
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uint32_t block_size;
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uint32_t mmap_addr;
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} __packed;
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/*
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* Reads a chunk of raw data with size @bufsize from the block specified by
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* @block_id starting at @bufoffset.
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* The read data is placed in memory pointed to by @buf.
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*
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* @block_id must be less than num_blocks
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* @bufoffset + @bufsize must be less than block_size
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*/
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struct smmstore_params_raw_write {
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uint32_t bufsize;
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uint32_t bufoffset;
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uint32_t block_id;
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} __packed;
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/*
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* Writes a chunk of raw data with size @bufsize to the block specified by
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* @block_id starting at @bufoffset.
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*
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* @block_id must be less than num_blocks
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* @bufoffset + @bufsize must be less than block_size
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*/
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struct smmstore_params_raw_read {
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uint32_t bufsize;
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uint32_t bufoffset;
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uint32_t block_id;
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} __packed;
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/*
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* Erases the specified block.
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*
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* @block_id must be less than num_blocks
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*/
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struct smmstore_params_raw_clear {
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uint32_t block_id;
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} __packed;
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/* SMM handler */
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uint32_t smmstore_exec(uint8_t command, void *param);
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/* Implementation of Version 1 */
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int smmstore_read_region(void *buf, ssize_t *bufsize);
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int smmstore_append_data(void *key, uint32_t key_sz, void *value, uint32_t value_sz);
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int smmstore_clear_region(void);
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/* Implementation of Version 2 */
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int smmstore_init(void *buf, size_t len);
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int smmstore_rawread_region(uint32_t block_id, uint32_t offset, uint32_t bufsize);
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int smmstore_rawwrite_region(uint32_t block_id, uint32_t offset, uint32_t bufsize);
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int smmstore_rawclear_region(uint32_t block_id);
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#if ENV_RAMSTAGE
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int smmstore_get_info(struct smmstore_params_info *info);
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#endif
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/* Advertise SMMSTORE v2 support */
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struct lb_header;
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void lb_smmstorev2(struct lb_header *header);
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#endif
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