Virtchnl failures can be hard to debug without logs. Logging the details
of virtchnl transactions can be useful for debugging virtchnl-related
issues.

Tested: Built & booted on a test machine and synthetically produced a
virtual failure to produce the following log:

idpf 0000:01:00.0: Non-zero virtchnl ret val 6 (msg op: 1, data_len: 8);
xn id: 0, cookie: 0
idpf 0000:01:00.0: Transaction failed (op 1, xn state:
3, id: 0, cookie: 0, size: 8)

Signed-off-by: Li Li <redacted>
---
v4:
 - Simplify logging to reduce redundant "ret val"s.
 - Use %u for xn->state.
v3:
 - Use dev_err_ratelimited in both logs.
 - Move log placement to after virtchnl field validation.
 - Remove redundant op/cookie fields since they were validated.
v2:
 - Use dev_warn_ratelimited instead of dev_notice_ratelimited based on
   reviewer feedback.
 drivers/net/ethernet/intel/libie/controlq.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/net/ethernet/intel/libie/controlq.c b/drivers/net/ethernet/intel/libie/controlq.c
index ebc05355e39d..e1bc19d6cdbf 100644
--- a/drivers/net/ethernet/intel/libie/controlq.c
+++ b/drivers/net/ethernet/intel/libie/controlq.c

@@ -766,6 +766,14 @@ libie_ctlq_xn_process_recv(struct libie_ctlq_xn_recv_params *params,
 	    msg_cookie != xn->cookie)
 		return false;
 
+	if (ctlq_msg->chnl_retval) {
+		dev_err_ratelimited(
+			params->ctlq->dev,
+			"Non-zero virtchnl ret val %u (msg op: %u, data_len: %u); xn id: %u, cookie: %u\n",
+			ctlq_msg->chnl_retval, ctlq_msg->chnl_opcode,
+			ctlq_msg->data_len, xn->index, xn->cookie);
+	}
+
 	spin_lock(&xn->xn_lock);
 	if (xn->state != LIBIE_CTLQ_XN_ASYNC &&
 	    xn->state != LIBIE_CTLQ_XN_WAITING) {

@@ -1011,6 +1019,11 @@ int libie_ctlq_xn_send(struct libie_ctlq_xn_send_params *params)
 		params->recv_mem = xn->recv_mem;
 		break;
 	default:
+		dev_err_ratelimited(
+			params->ctlq->dev,
+			"Transaction failed (op %u, xn state: %u, id: %u, cookie: %u, size: %zu)\n",
+			params->chnl_opcode, xn->state, xn->index, xn->cookie,
+			xn->recv_mem.iov_len);
 		ret = -EBADMSG;
 		break;
 	}

-- 
2.54.0.545.g6539524ca2-goog