nvme: Implement Enhanced Command Retry

index c418b7a347e0..81d4514b9d06 100644
@@ -244,6 +244,22 @@ static inline bool nvme_req_needs_retry(struct request *req)
 	return true;
 }
 
+static void nvme_retry_req(struct request *req)
+{
+	struct nvme_ns *ns = req->q->queuedata;
+	unsigned long delay = 0;
+	u16 crd;
+
+	/* The mask and shift result must be <= 3 */
+	crd = (nvme_req(req)->status & NVME_SC_CRD) >> 11;
+	if (ns && crd)
+		delay = ns->ctrl->crdt[crd - 1] * 100;
+
+	nvme_req(req)->retries++;
+	blk_mq_requeue_request(req, false);
+	blk_mq_delay_kick_requeue_list(req->q, delay);
+}
+
 void nvme_complete_rq(struct request *req)
 {
 	blk_status_t status = nvme_error_status(req);

@@ -261,8 +277,7 @@ void nvme_complete_rq(struct request *req)
 		}
 
 		if (!blk_queue_dying(req->q)) {
-			nvme_req(req)->retries++;
-			blk_mq_requeue_request(req, true);
+			nvme_retry_req(req);
 			return;
 		}
 	}

@@ -1883,6 +1898,26 @@ static int nvme_configure_timestamp(struct nvme_ctrl *ctrl)
 	return ret;
 }
 
+static int nvme_configure_acre(struct nvme_ctrl *ctrl)
+{
+	struct nvme_feat_host_behavior *host;
+	int ret;
+
+	/* Don't bother enabling the feature if retry delay is not reported */
+	if (!ctrl->crdt[0])
+		return 0;
+
+	host = kzalloc(sizeof(*host), GFP_KERNEL);
+	if (!host)
+		return 0;
+
+	host->acre = NVME_ENABLE_ACRE;
+	ret = nvme_set_features(ctrl, NVME_FEAT_HOST_BEHAVIOR, 0,
+				host, sizeof(*host), NULL);
+	kfree(host);
+	return ret;
+}
+
 static int nvme_configure_apst(struct nvme_ctrl *ctrl)
 {
 	/*

@@ -2404,6 +2439,10 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
 		ctrl->quirks &= ~NVME_QUIRK_NO_DEEPEST_PS;
 	}
 
+	ctrl->crdt[0] = le16_to_cpu(id->crdt1);
+	ctrl->crdt[1] = le16_to_cpu(id->crdt2);
+	ctrl->crdt[2] = le16_to_cpu(id->crdt3);
+
 	ctrl->oacs = le16_to_cpu(id->oacs);
 	ctrl->oncs = le16_to_cpup(&id->oncs);
 	ctrl->oaes = le32_to_cpu(id->oaes);

@@ -2504,6 +2543,10 @@ int nvme_init_identify(struct nvme_ctrl *ctrl)
 	if (ret < 0)
 		return ret;
 
+	ret = nvme_configure_acre(ctrl);
+	if (ret < 0)
+		return ret;
+
 	ctrl->identified = true;
 
 	return 0;

index 27663ce3044e..51063dbf08bf 100644
@@ -181,6 +181,7 @@ struct nvme_ctrl {
 	u32 page_size;
 	u32 max_hw_sectors;
 	u32 max_segments;
+	u16 crdt[3];
 	u16 oncs;
 	u16 oacs;
 	u16 nssa;

index c03973c215ad..88812cb15be0 100644
@@ -223,7 +223,11 @@ struct nvme_id_ctrl {
 	__le32			rtd3e;
 	__le32			oaes;
 	__le32			ctratt;
-	__u8			rsvd100[156];
+	__u8			rsvd100[28];
+	__le16			crdt1;
+	__le16			crdt2;
+	__le16			crdt3;
+	__u8			rsvd134[122];
 	__le16			oacs;
 	__u8			acl;
 	__u8			aerl;

@@ -756,6 +760,15 @@ enum {
 	NVME_HOST_MEM_RETURN	= (1 << 1),
 };
 
+struct nvme_feat_host_behavior {
+	__u8 acre;
+	__u8 resv1[511];
+};
+
+enum {
+	NVME_ENABLE_ACRE	= 1,
+};
+
 /* Admin commands */
 
 enum nvme_admin_opcode {

@@ -810,6 +823,7 @@ enum {
 	NVME_FEAT_RRL		= 0x12,
 	NVME_FEAT_PLM_CONFIG	= 0x13,
 	NVME_FEAT_PLM_WINDOW	= 0x14,
+	NVME_FEAT_HOST_BEHAVIOR	= 0x16,
 	NVME_FEAT_SW_PROGRESS	= 0x80,
 	NVME_FEAT_HOST_ID	= 0x81,
 	NVME_FEAT_RESV_MASK	= 0x82,

@@ -1265,6 +1279,7 @@ enum {
 	NVME_SC_ANA_TRANSITION		= 0x303,
 	NVME_SC_HOST_PATH_ERROR		= 0x370,
 
+	NVME_SC_CRD			= 0x1800,
 	NVME_SC_DNR			= 0x4000,
 };