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-rw-r--r--drivers/virt/coco/sev-guest/sev-guest.c20
1 files changed, 17 insertions, 3 deletions
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 4ec4174e05a3..7b4e9009f335 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -377,9 +377,26 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
snp_dev->input.data_npages = certs_npages;
}
+ /*
+ * Increment the message sequence number. There is no harm in doing
+ * this now because decryption uses the value stored in the response
+ * structure and any failure will wipe the VMPCK, preventing further
+ * use anyway.
+ */
+ snp_inc_msg_seqno(snp_dev);
+
if (fw_err)
*fw_err = err;
+ /*
+ * If an extended guest request was issued and the supplied certificate
+ * buffer was not large enough, a standard guest request was issued to
+ * prevent IV reuse. If the standard request was successful, return -EIO
+ * back to the caller as would have originally been returned.
+ */
+ if (!rc && err == SNP_GUEST_REQ_INVALID_LEN)
+ return -EIO;
+
if (rc) {
dev_alert(snp_dev->dev,
"Detected error from ASP request. rc: %d, fw_err: %llu\n",
@@ -395,9 +412,6 @@ static int handle_guest_request(struct snp_guest_dev *snp_dev, u64 exit_code, in
goto disable_vmpck;
}
- /* Increment to new message sequence after payload decryption was successful. */
- snp_inc_msg_seqno(snp_dev);
-
return 0;
disable_vmpck: