mrc_cache: Move code for triggering memory training into mrc_cache

Currently the decision of whether or not to use mrc_cache in recovery
mode is made within the individual platforms' drivers (ie: fsp2.0,
fsp1.1, etc.).  As this is not platform specific, but uses common
vboot infrastructure, the code can be unified and moved into
mrc_cache.  The conditions are as follows:

  1.  If HAS_RECOVERY_MRC_CACHE, use mrc_cache data (unless retrain
      switch is true)
  2.  If !HAS_RECOVERY_MRC_CACHE && VBOOT_STARTS_IN_BOOTBLOCK, this
      means that memory training will occur after verified boot,
      meaning that mrc_cache will be filled with data from executing
      RW code.  So in this case, we never want to use the training
      data in the mrc_cache for recovery mode.
  3.  If !HAS_RECOVERY_MRC_CACHE && VBOOT_STARTS_IN_ROMSTAGE, this
      means that memory training happens before verfied boot, meaning
      that the mrc_cache data is generated by RO code, so it is safe
      to use for a recovery boot.
  4.  Any platform that does not use vboot should be unaffected.

Additionally, we have removed the
MRC_CLEAR_NORMAL_CACHE_ON_RECOVERY_RETRAIN config because the
mrc_cache driver takes care of invalidating the mrc_cache data for
normal mode.  If the platform:
  1.  !HAS_RECOVERY_MRC_CACHE, always invalidate mrc_cache data
  2.  HAS_RECOVERY_MRC_CACHE, only invalidate if retrain switch is set

BUG=b:150502246
BRANCH=None
TEST=1. run dut-control power_state:rec_force_mrc twice on lazor
        ensure that memory retraining happens both times
        run dut-control power_state:rec twice on lazor
        ensure that memory retraining happens only first time
     2. remove HAS_RECOVERY_MRC_CACHE from lazor Kconfig
        boot twice to ensure caching of memory training occurred
	on each boot.

Change-Id: I3875a7b4a4ba3c1aa8a3c1507b3993036a7155fc
Signed-off-by: Shelley Chen <shchen@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46855
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

2 files changed, 58 insertions, 17 deletions

diff --git a/src/drivers/mrc_cache/Kconfig b/src/drivers/mrc_cache/Kconfig
index b09c19672e..df6973b0a4 100644
--- a/src/drivers/mrc_cache/Kconfig
+++ b/src/drivers/mrc_cache/Kconfig
@@ -17,11 +17,6 @@ config HAS_RECOVERY_MRC_CACHE
 	bool
 	default n
 
-config MRC_CLEAR_NORMAL_CACHE_ON_RECOVERY_RETRAIN
-	bool
-	depends on VBOOT_STARTS_IN_BOOTBLOCK
-	default n
-
 config MRC_SETTINGS_VARIABLE_DATA
 	bool
 	default n
diff --git a/src/drivers/mrc_cache/mrc_cache.c b/src/drivers/mrc_cache/mrc_cache.c
index eb43123c67..8b26ea5905 100644
--- a/src/drivers/mrc_cache/mrc_cache.c
+++ b/src/drivers/mrc_cache/mrc_cache.c
@@ -69,7 +69,20 @@ static const struct cache_region normal_training = {
 	.type = MRC_TRAINING_DATA,
 	.elog_slot = ELOG_MEM_CACHE_UPDATE_SLOT_NORMAL,
 	.tpm_hash_index = MRC_RW_HASH_NV_INDEX,
+#if CONFIG(VBOOT_STARTS_IN_ROMSTAGE)
+	/*
+	 * If VBOOT_STARTS_IN_ROMSTAGE is selected, this means that
+	 * memory training happens before vboot (in RO) and the
+	 * mrc_cache data is always safe to use.
+	 */
 	.flags = NORMAL_FLAG | RECOVERY_FLAG,
+#else
+	/*
+	 * If !VBOOT_STARTS_IN_ROMSTAGE, this means that memory training happens after
+	 * vboot (in RW code) and is never safe to use in recovery.
+	 */
+	.flags = NORMAL_FLAG,
+#endif
 };
 
 static const struct cache_region variable_data = {
@@ -78,7 +91,20 @@ static const struct cache_region variable_data = {
 	.type = MRC_VARIABLE_DATA,
 	.elog_slot = ELOG_MEM_CACHE_UPDATE_SLOT_VARIABLE,
 	.tpm_hash_index = 0,
+#if CONFIG(VBOOT_STARTS_IN_ROMSTAGE)
+	/*
+	 * If VBOOT_STARTS_IN_ROMSTAGE is selected, this means that
+	 * memory training happens before vboot (in RO) and the
+	 * mrc_cache data is always safe to use.
+	 */
 	.flags = NORMAL_FLAG | RECOVERY_FLAG,
+#else
+	/*
+	 * If !VBOOT_STARTS_IN_ROMSTAGE, this means that memory training happens after
+	 * vboot (in RW code) and is never safe to use in recovery.
+	 */
+	.flags = NORMAL_FLAG,
+#endif
 };
 
 /* Order matters here for priority in matching. */
@@ -255,6 +281,13 @@ static int mrc_cache_find_current(int type, uint32_t version,
 	const size_t md_size = sizeof(*md);
 	const bool fail_bad_data = true;
 
+	/*
+	 * In recovery mode, force retraining if the memory retrain
+	 * switch is set.
+	 */
+	if (vboot_recovery_mode_enabled() && get_recovery_mode_retrain_switch())
+		return -1;
+
 	cr = lookup_region(&region, type);
 
 	if (cr == NULL)
@@ -566,10 +599,24 @@ static void invalidate_normal_cache(void)
 	const char *name = DEFAULT_MRC_CACHE;
 	const uint32_t invalid = ~MRC_DATA_SIGNATURE;
 
-	/* Invalidate only on recovery mode with retraining enabled. */
+	/*
+	 * If !HAS_RECOVERY_MRC_CACHE and VBOOT_STARTS_IN_ROMSTAGE is
+	 * selected, this means that memory training occurs before
+	 * verified boot (in RO), so normal mode cache does not need
+	 * to be invalidated.
+	 */
+	if (!CONFIG(HAS_RECOVERY_MRC_CACHE) && CONFIG(VBOOT_STARTS_IN_ROMSTAGE))
+		return;
+
+	/* We only invalidate the normal cache in recovery mode. */
 	if (!vboot_recovery_mode_enabled())
 		return;
-	if (!get_recovery_mode_retrain_switch())
+
+	/*
+	 * For platforms with a recovery mrc_cache, no need to
+	 * invalidate when retrain switch is not set.
+	 */
+	if (CONFIG(HAS_RECOVERY_MRC_CACHE) && !get_recovery_mode_retrain_switch())
 		return;
 
 	if (fmap_locate_area_as_rdev_rw(name, &rdev) < 0) {
@@ -599,7 +646,7 @@ static void update_mrc_cache_from_cbmem(int type)
 	cr = lookup_region(&region, type);
 
 	if (cr == NULL) {
-		printk(BIOS_ERR, "MRC: could not find cache_region type %d\n", type);
+		printk(BIOS_INFO, "MRC: could not find cache_region type %d\n", type);
 		return;
 	}
 
@@ -631,8 +678,7 @@ static void finalize_mrc_cache(void *unused)
 			update_mrc_cache_from_cbmem(MRC_VARIABLE_DATA);
 	}
 
-	if (CONFIG(MRC_CLEAR_NORMAL_CACHE_ON_RECOVERY_RETRAIN))
-		invalidate_normal_cache();
+	invalidate_normal_cache();
 
 	protect_mrc_region();
 }
@@ -642,13 +688,6 @@ int mrc_cache_stash_data(int type, uint32_t version, const void *data,
 {
 	const struct cache_region *cr;
 
-	cr = lookup_region_type(type);
-	if (cr == NULL) {
-		printk(BIOS_ERR, "MRC: failed to add to cbmem for type %d.\n",
-			type);
-		return -1;
-	}
-
 	struct mrc_metadata md = {
 		.signature = MRC_DATA_SIGNATURE,
 		.data_size = size,
@@ -664,6 +703,13 @@ int mrc_cache_stash_data(int type, uint32_t version, const void *data,
 		size_t cbmem_size;
 		cbmem_size = sizeof(*cbmem_md) + size;
 
+		cr = lookup_region_type(type);
+		if (cr == NULL) {
+			printk(BIOS_INFO, "MRC: No region type found. Skip adding to cbmem for type %d.\n",
+				type);
+			return 0;
+		}
+
 		cbmem_md = cbmem_add(cr->cbmem_id, cbmem_size);
 
 		if (cbmem_md == NULL) {