drivers/smmstore: add ability to write to whole flash

With DRIVERS_EFI_UPDATE_CAPSULES enabled, SMMSTORE SMI handler can use commands with highest bit (0x80) set to access whole flash instead of just the SMMSTORE region. The rest of interface is identical to regular SMMSTORE v2. Change-Id: I7f3dbfa965b9dcbade8b2f06a5bd2ac1345c7972 Signed-off-by: Krystian Hebel <[email protected]>
Dasharo · Jun 28, 2024 · 623abec · 623abec
1 parent 628cce5
commit 623abec
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Showing 3 changed files with 34 additions and 0 deletions.
diff --git a/src/drivers/smmstore/smi.c b/src/drivers/smmstore/smi.c
@@ -143,6 +143,9 @@ static uint32_t smmstorev2_exec(uint8_t command, void *param)
 
 uint32_t smmstore_exec(uint8_t command, void *param)
 {
+	if (smmstore_preprocess_cmd(&command))
+		return SMMSTORE_RET_SUCCESS;
+
 	if (command != SMMSTORE_CMD_CLEAR && !param)
 		return SMMSTORE_RET_FAILURE;
 

diff --git a/src/drivers/smmstore/store.c b/src/drivers/smmstore/store.c
@@ -47,8 +47,34 @@ _Static_assert(SMM_BLOCK_SIZE <= FMAP_SECTION_SMMSTORE_SIZE,
  * crash/reboot could clear out all variables.
  */
 
+static int use_full_flash;
+
+int smmstore_preprocess_cmd(uint8_t *cmd)
+{
+	if (CONFIG(DRIVERS_EFI_UPDATE_CAPSULES)) {
+		if (*cmd & SMMSTORE_CMD_USE_FULL_FLASH) {
+			use_full_flash = 1;
+			*cmd &= ~SMMSTORE_CMD_USE_FULL_FLASH;
+		} else {
+			use_full_flash = 0;
+		}
+	}
+
+	return 0;
+}
+
 static enum cb_err lookup_store_region(struct region *region)
 {
+	if (CONFIG(DRIVERS_EFI_UPDATE_CAPSULES) && use_full_flash) {
+		const struct region_device *rdev = boot_device_rw();
+
+		if (rdev == NULL)
+			return CB_ERR;
+
+		*region = *region_device_region(rdev);
+		return CB_SUCCESS;
+	}
+
 	if (fmap_locate_area(SMMSTORE_REGION, region)) {
 		printk(BIOS_WARNING,
 		       "smm store: Unable to find SMM store FMAP region '%s'\n",

diff --git a/src/include/smmstore.h b/src/include/smmstore.h
@@ -21,6 +21,9 @@
 #define SMMSTORE_CMD_RAW_WRITE 6
 #define SMMSTORE_CMD_RAW_CLEAR 7
 
+/* Used by capsule updates */
+#define SMMSTORE_CMD_USE_FULL_FLASH 0x80
+
 /* Version 1 */
 struct smmstore_params_read {
 	void *buf;
@@ -117,6 +120,8 @@ int smmstore_get_info(struct smmstore_params_info *info);
 #endif
 struct region_device;
 int smmstore_lookup_region(struct region_device *rstore);
+/* Returns 0 if normal parsing should continue, 1 otherwise */
+int smmstore_preprocess_cmd(uint8_t *cmd);
 
 /* Advertise SMMSTORE v2 support */
 struct lb_header;