From bc744f5893fc4d53275ed26dd8d968011c6a09c1 Mon Sep 17 00:00:00 2001 From: Patrick Rudolph Date: Fri, 17 Apr 2020 16:16:49 +0200 Subject: drivers/smmstore: Implement SMMSTORE version 2 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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: https://github.com/9elements/edk2-1/commit/eb1127744a3a5d5c8ac4e8eb76f07e79c736dbe2 Change-Id: I25e49d184135710f3e6dd1ad3bed95de950fe057 Signed-off-by: Patrick Rudolph Signed-off-by: Christian Walter Reviewed-on: https://review.coreboot.org/c/coreboot/+/40520 Tested-by: build bot (Jenkins) Reviewed-by: Michał Żygowski Reviewed-by: Matt DeVillier --- src/include/smmstore.h | 94 +++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 90 insertions(+), 4 deletions(-) (limited to 'src/include/smmstore.h') diff --git a/src/include/smmstore.h b/src/include/smmstore.h index ff0b72001a..2c37ca39b9 100644 --- a/src/include/smmstore.h +++ b/src/include/smmstore.h @@ -10,10 +10,18 @@ #define SMMSTORE_RET_FAILURE 1 #define SMMSTORE_RET_UNSUPPORTED 2 +/* Version 1 */ #define SMMSTORE_CMD_CLEAR 1 #define SMMSTORE_CMD_READ 2 #define SMMSTORE_CMD_APPEND 3 +/* Version 2 */ +#define SMMSTORE_CMD_INIT 4 +#define SMMSTORE_CMD_RAW_READ 5 +#define SMMSTORE_CMD_RAW_WRITE 6 +#define SMMSTORE_CMD_RAW_CLEAR 7 + +/* Version 1 */ struct smmstore_params_read { void *buf; ssize_t bufsize; @@ -26,12 +34,90 @@ struct smmstore_params_append { size_t valsize; }; -/* SMM responder */ +/* Version 2 */ +/* + * The Version 2 protocol separates the SMMSTORE into 64KiB blocks, each + * of which can be read/written/cleared in an independent manner. The + * data format isn't specified. See documentation page for more details. + */ + +#define SMM_BLOCK_SIZE (64 * KiB) + +/* + * Sets the communication buffer to use for read and write operations. + */ +struct smmstore_params_init { + uint32_t com_buffer; + uint32_t com_buffer_size; +} __packed; + +/* + * Returns the number of blocks the SMMSTORE supports and their size. + * For EDK2 this should be at least two blocks with 64 KiB each. + * The mmap_addr is set the memory mapped physical address of the SMMSTORE. + */ +struct smmstore_params_info { + uint32_t num_blocks; + uint32_t block_size; + uint32_t mmap_addr; +} __packed; + +/* + * Reads a chunk of raw data with size @bufsize from the block specified by + * @block_id starting at @bufoffset. + * The read data is placed in memory pointed to by @buf. + * + * @block_id must be less than num_blocks + * @bufoffset + @bufsize must be less than block_size + */ +struct smmstore_params_raw_write { + uint32_t bufsize; + uint32_t bufoffset; + uint32_t block_id; +} __packed; + +/* + * Writes a chunk of raw data with size @bufsize to the block specified by + * @block_id starting at @bufoffset. + * + * @block_id must be less than num_blocks + * @bufoffset + @bufsize must be less than block_size + */ +struct smmstore_params_raw_read { + uint32_t bufsize; + uint32_t bufoffset; + uint32_t block_id; +} __packed; + +/* + * Erases the specified block. + * + * @block_id must be less than num_blocks + */ +struct smmstore_params_raw_clear { + uint32_t block_id; +} __packed; + + +/* SMM handler */ uint32_t smmstore_exec(uint8_t command, void *param); -/* implementation */ +/* Implementation of Version 1 */ int smmstore_read_region(void *buf, ssize_t *bufsize); -int smmstore_append_data(void *key, uint32_t key_sz, - void *value, uint32_t value_sz); +int smmstore_append_data(void *key, uint32_t key_sz, void *value, uint32_t value_sz); int smmstore_clear_region(void); + +/* Implementation of Version 2 */ +int smmstore_init(void *buf, size_t len); +int smmstore_rawread_region(uint32_t block_id, uint32_t offset, uint32_t bufsize); +int smmstore_rawwrite_region(uint32_t block_id, uint32_t offset, uint32_t bufsize); +int smmstore_rawclear_region(uint32_t block_id); +#if ENV_RAMSTAGE +int smmstore_get_info(struct smmstore_params_info *info); +#endif + +/* Advertise SMMSTORE v2 support */ +struct lb_header; +void lb_smmstorev2(struct lb_header *header); + #endif -- cgit v1.2.3