[coreboot-gerrit] Change in coreboot[master]: mrc_cache: Remove unnecessary data checksum calculation

[Julius Werner (Code Review)]

Julius Werner has submitted this change. ( https://review.coreboot.org/c/coreboot/+/46515 )

Change subject: mrc_cache: Remove unnecessary data checksum calculation
......................................................................

mrc_cache: Remove unnecessary data checksum calculation

When MRC_SAVE_HASH_IN_TPM is selected, we can just use the TPM hash to
verify the MRC_CACHE data.  Thus, we don't need to calculate the
checksum anymore in this case.

BUG=b:150502246
BRANCH=None
TEST=make sure memory training still works on nami

Change-Id: I1db4469da49755805b541f50c7ef2f9cdb749425
Signed-off-by: Shelley Chen 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/46515
Tested-by: build bot (Jenkins) 
Reviewed-by: Furquan Shaikh 
---
M src/drivers/mrc_cache/mrc_cache.c
1 file changed, 12 insertions(+), 11 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Furquan Shaikh: Looks good to me, approved

diff --git a/src/drivers/mrc_cache/mrc_cache.c b/src/drivers/mrc_cache/mrc_cache.c
index 1bbb426..3b98dba 100644
--- a/src/drivers/mrc_cache/mrc_cache.c
+++ b/src/drivers/mrc_cache/mrc_cache.c
@@ -193,18 +193,19 @@
    if (md->data_size != data_size)
    	return -1;

-	checksum = compute_ip_checksum(data, data_size);
-
-	if (md->data_checksum != checksum) {
-		printk(BIOS_ERR, "MRC: data checksum mismatch: %x vs %x\n",
-			md->data_checksum, checksum);
-		return -1;
-	}
-
    hash_idx = cr->tpm_hash_index;
-	if (hash_idx && CONFIG(MRC_SAVE_HASH_IN_TPM) &&
-	    !mrc_cache_verify_hash(hash_idx, data, data_size))
-		return -1;
+	if (hash_idx && CONFIG(MRC_SAVE_HASH_IN_TPM)) {
+		if (!mrc_cache_verify_hash(hash_idx, data, data_size))
+			return -1;
+	} else {
+		checksum = compute_ip_checksum(data, data_size);
+
+		if (md->data_checksum != checksum) {
+			printk(BIOS_ERR, "MRC: data checksum mismatch: %x vs %x\n",
+			       md->data_checksum, checksum);
+			return -1;
+		}
+	}

return 0;
 }