crypto: cavium/nitrox - fix for command corruption in queue full case with backlog submissions.

Earlier used to post the current command without checking queue full
     after backlog submissions. So, post the current command only after
     confirming the space in queue after backlog submissions.

     Maintain host write index instead of reading device registers
     to get the next free slot to post the command.

     Return -ENOSPC in queue full case.

Signed-off-by: Srikanth Jampala <Jampala.Srikanth@cavium.com>
Reviewed-by: Gadam Sreerama <sgadam@cavium.com>
Tested-by: Jha, Chandan <Chandan.Jha@cavium.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

drivers/crypto/cavium/nitrox/nitrox_dev.h

@@ -35,6 +35,7 @@ struct nitrox_cmdq {
 	/* requests in backlog queues */
 	atomic_t backlog_count;
 
+	int write_idx;
 	/* command size 32B/64B */
 	u8 instr_size;
 	u8 qno;
@@ -87,7 +88,7 @@ struct nitrox_bh {
 	struct bh_data *slc;
 };
 
-/* NITROX-5 driver state */
+/* NITROX-V driver state */
 #define NITROX_UCODE_LOADED	0
 #define NITROX_READY		1
 

drivers/crypto/cavium/nitrox/nitrox_lib.c

@@ -36,6 +36,7 @@ static int cmdq_common_init(struct nitrox_cmdq *cmdq)
 	cmdq->head = PTR_ALIGN(cmdq->head_unaligned, PKT_IN_ALIGN);
 	cmdq->dma = PTR_ALIGN(cmdq->dma_unaligned, PKT_IN_ALIGN);
 	cmdq->qsize = (qsize + PKT_IN_ALIGN);
+	cmdq->write_idx = 0;
 
 	spin_lock_init(&cmdq->response_lock);
 	spin_lock_init(&cmdq->cmdq_lock);

drivers/crypto/cavium/nitrox/nitrox_reqmgr.c

@@ -42,6 +42,16 @@
  *   Invalid flag options in AES-CCM IV.
  */
 
+static inline int incr_index(int index, int count, int max)
+{
+	if ((index + count) >= max)
+		index = index + count - max;
+	else
+		index += count;
+
+	return index;
+}
+
 /**
  * dma_free_sglist - unmap and free the sg lists.
  * @ndev: N5 device
@@ -426,30 +436,29 @@ static void post_se_instr(struct nitrox_softreq *sr,
 			  struct nitrox_cmdq *cmdq)
 {
 	struct nitrox_device *ndev = sr->ndev;
-	union nps_pkt_in_instr_baoff_dbell pkt_in_baoff_dbell;
-	u64 offset;
+	int idx;
 	u8 *ent;
 
 	spin_lock_bh(&cmdq->cmdq_lock);
 
-	/* get the next write offset */
-	offset = NPS_PKT_IN_INSTR_BAOFF_DBELLX(cmdq->qno);
-	pkt_in_baoff_dbell.value = nitrox_read_csr(ndev, offset);
+	idx = cmdq->write_idx;
 	/* copy the instruction */
-	ent = cmdq->head + pkt_in_baoff_dbell.s.aoff;
+	ent = cmdq->head + (idx * cmdq->instr_size);
 	memcpy(ent, &sr->instr, cmdq->instr_size);
-	/* flush the command queue updates */
-	dma_wmb();
 
-	sr->tstamp = jiffies;
 	atomic_set(&sr->status, REQ_POSTED);
 	response_list_add(sr, cmdq);
+	sr->tstamp = jiffies;
+	/* flush the command queue updates */
+	dma_wmb();
 
 	/* Ring doorbell with count 1 */
 	writeq(1, cmdq->dbell_csr_addr);
 	/* orders the doorbell rings */
 	mmiowb();
 
+	cmdq->write_idx = incr_index(idx, 1, ndev->qlen);
+
 	spin_unlock_bh(&cmdq->cmdq_lock);
 }
 
@@ -459,6 +468,9 @@ static int post_backlog_cmds(struct nitrox_cmdq *cmdq)
 	struct nitrox_softreq *sr, *tmp;
 	int ret = 0;
 
+	if (!atomic_read(&cmdq->backlog_count))
+		return 0;
+
 	spin_lock_bh(&cmdq->backlog_lock);
 
 	list_for_each_entry_safe(sr, tmp, &cmdq->backlog_head, backlog) {
@@ -466,7 +478,7 @@ static int post_backlog_cmds(struct nitrox_cmdq *cmdq)
 
 		/* submit until space available */
 		if (unlikely(cmdq_full(cmdq, ndev->qlen))) {
-			ret = -EBUSY;
+			ret = -ENOSPC;
 			break;
 		}
 		/* delete from backlog list */
@@ -491,23 +503,20 @@ static int nitrox_enqueue_request(struct nitrox_softreq *sr)
 {
 	struct nitrox_cmdq *cmdq = sr->cmdq;
 	struct nitrox_device *ndev = sr->ndev;
-	int ret = -EBUSY;
+
+	/* try to post backlog requests */
+	post_backlog_cmds(cmdq);
 
 	if (unlikely(cmdq_full(cmdq, ndev->qlen))) {
 		if (!(sr->flags & CRYPTO_TFM_REQ_MAY_BACKLOG))
-			return -EAGAIN;
-
+			return -ENOSPC;
+		/* add to backlog list */
 		backlog_list_add(sr, cmdq);
-	} else {
-		ret = post_backlog_cmds(cmdq);
-		if (ret) {
-			backlog_list_add(sr, cmdq);
-			return ret;
-		}
-		post_se_instr(sr, cmdq);
-		ret = -EINPROGRESS;
+		return -EBUSY;
 	}
-	return ret;
+	post_se_instr(sr, cmdq);
+
+	return -EINPROGRESS;
 }
 
 /**
@@ -624,11 +633,9 @@ int nitrox_process_se_request(struct nitrox_device *ndev,
 	 */
 	sr->instr.fdata[0] = *((u64 *)&req->gph);
 	sr->instr.fdata[1] = 0;
-	/* flush the soft_req changes before posting the cmd */
-	wmb();
 
 	ret = nitrox_enqueue_request(sr);
-	if (ret == -EAGAIN)
+	if (ret == -ENOSPC)
 		goto send_fail;
 
 	return ret;