enic: enic rq code reorg

JIRA: https://issues.redhat.com/browse/RHEL-84863

commit eaa23db
Author: Satish Kharat <satishkh@cisco.com>
Date:   Tue Mar 4 19:56:38 2025 -0500

    enic: enic rq code reorg

    Separates enic rx path from generic vnic api. Removes some
    complexity of doign enic callbacks through vnic api in rx.
    This is in preparation for enabling enic extended cq which
    applies only to enic rx path.

    Co-developed-by: Nelson Escobar <neescoba@cisco.com>
    Signed-off-by: Nelson Escobar <neescoba@cisco.com>
    Co-developed-by: John Daley <johndale@cisco.com>
    Signed-off-by: John Daley <johndale@cisco.com>
    Signed-off-by: Satish Kharat <satishkh@cisco.com>
    Link: https://patch.msgid.link/20250304-enic_cleanup_and_ext_cq-v2-2-85804263dad8@cisco.com
    Signed-off-by: Paolo Abeni <pabeni@redhat.com>

Signed-off-by: Nelson Escobar <nescobar@redhat.com>

Author: Nelson Escobar

drivers/net/ethernet/cisco/enic/enic_main.c

@@ -1386,8 +1386,7 @@ static int enic_poll(struct napi_struct *napi, int budget)
 				       enic_wq_service, NULL);
 
 	if (budget > 0)
-		rq_work_done = vnic_cq_service(&enic->cq[cq_rq],
-			rq_work_to_do, enic_rq_service, NULL);
+		rq_work_done = enic_rq_cq_service(enic, cq_rq, rq_work_to_do);
 
 	/* Accumulate intr event credits for this polling
 	 * cycle.  An intr event is the completion of a
@@ -1516,8 +1515,7 @@ static int enic_poll_msix_rq(struct napi_struct *napi, int budget)
 	 */
 
 	if (budget > 0)
-		work_done = vnic_cq_service(&enic->cq[cq],
-			work_to_do, enic_rq_service, NULL);
+		work_done = enic_rq_cq_service(enic, cq, work_to_do);
 
 	/* Return intr event credits for this polling
 	 * cycle.  An intr event is the completion of a

drivers/net/ethernet/cisco/enic/enic_rq.c

@@ -21,14 +21,26 @@ static void enic_intr_update_pkt_size(struct vnic_rx_bytes_counter *pkt_size,
 		pkt_size->small_pkt_bytes_cnt += pkt_len;
 }
 
-int enic_rq_service(struct vnic_dev *vdev, struct cq_desc *cq_desc, u8 type,
-		    u16 q_number, u16 completed_index, void *opaque)
+static void enic_rq_cq_desc_dec(struct cq_enet_rq_desc *desc, u8 *type,
+				u8 *color, u16 *q_number, u16 *completed_index)
 {
-	struct enic *enic = vnic_dev_priv(vdev);
-
-	vnic_rq_service(&enic->rq[q_number].vrq, cq_desc, completed_index,
-			VNIC_RQ_RETURN_DESC, enic_rq_indicate_buf, opaque);
-	return 0;
+	/* type_color is the last field for all cq structs */
+	u8 type_color = desc->type_color;
+
+	/* Make sure color bit is read from desc *before* other fields
+	 * are read from desc.  Hardware guarantees color bit is last
+	 * bit (byte) written.  Adding the rmb() prevents the compiler
+	 * and/or CPU from reordering the reads which would potentially
+	 * result in reading stale values.
+	 */
+	rmb();
+
+	*q_number = le16_to_cpu(desc->q_number_rss_type_flags) &
+		CQ_DESC_Q_NUM_MASK;
+	*completed_index = le16_to_cpu(desc->completed_index_flags) &
+	CQ_DESC_COMP_NDX_MASK;
+	*color = (type_color >> CQ_DESC_COLOR_SHIFT) & CQ_DESC_COLOR_MASK;
+	*type = type_color & CQ_DESC_TYPE_MASK;
 }
 
 static void enic_rq_set_skb_flags(struct vnic_rq *vrq, u8 type, u32 rss_hash,
@@ -101,10 +113,9 @@ static void enic_rq_set_skb_flags(struct vnic_rq *vrq, u8 type, u32 rss_hash,
 	}
 }
 
-static void cq_enet_rq_desc_dec(struct cq_enet_rq_desc *desc, u8 *type,
-				u8 *color, u16 *q_number, u16 *completed_index,
-				u8 *ingress_port, u8 *fcoe, u8 *eop, u8 *sop,
-				u8 *rss_type, u8 *csum_not_calc, u32 *rss_hash,
+static void cq_enet_rq_desc_dec(struct cq_enet_rq_desc *desc, u8 *ingress_port,
+				u8 *fcoe, u8 *eop, u8 *sop, u8 *rss_type,
+				u8 *csum_not_calc, u32 *rss_hash,
 				u16 *bytes_written, u8 *packet_error,
 				u8 *vlan_stripped, u16 *vlan_tci,
 				u16 *checksum, u8 *fcoe_sof,
@@ -117,9 +128,6 @@ static void cq_enet_rq_desc_dec(struct cq_enet_rq_desc *desc, u8 *type,
 	u16 q_number_rss_type_flags;
 	u16 bytes_written_flags;
 
-	cq_desc_dec((struct cq_desc *)desc, type,
-		    color, q_number, completed_index);
-
 	completed_index_flags = le16_to_cpu(desc->completed_index_flags);
 	q_number_rss_type_flags =
 		le16_to_cpu(desc->q_number_rss_type_flags);
@@ -249,37 +257,33 @@ void enic_free_rq_buf(struct vnic_rq *rq, struct vnic_rq_buf *buf)
 	buf->os_buf = NULL;
 }
 
-void enic_rq_indicate_buf(struct vnic_rq *rq, struct cq_desc *cq_desc,
-			  struct vnic_rq_buf *buf, int skipped, void *opaque)
+static void enic_rq_indicate_buf(struct enic *enic, struct vnic_rq *rq,
+				 struct vnic_rq_buf *buf,
+				 struct cq_enet_rq_desc *cq_desc, u8 type,
+				 u16 q_number, u16 completed_index)
 {
-	struct enic *enic = vnic_dev_priv(rq->vdev);
 	struct sk_buff *skb;
 	struct vnic_cq *cq = &enic->cq[enic_cq_rq(enic, rq->index)];
 	struct enic_rq_stats *rqstats = &enic->rq[rq->index].stats;
 	struct napi_struct *napi;
 
-	u8 type, color, eop, sop, ingress_port, vlan_stripped;
+	u8 eop, sop, ingress_port, vlan_stripped;
 	u8 fcoe, fcoe_sof, fcoe_fc_crc_ok, fcoe_enc_error, fcoe_eof;
 	u8 tcp_udp_csum_ok, udp, tcp, ipv4_csum_ok;
 	u8 ipv6, ipv4, ipv4_fragment, fcs_ok, rss_type, csum_not_calc;
 	u8 packet_error;
-	u16 q_number, completed_index, bytes_written, vlan_tci, checksum;
+	u16 bytes_written, vlan_tci, checksum;
 	u32 rss_hash;
 
 	rqstats->packets++;
-	if (skipped) {
-		rqstats->desc_skip++;
-		return;
-	}
 
-	cq_enet_rq_desc_dec((struct cq_enet_rq_desc *)cq_desc, &type, &color,
-			    &q_number, &completed_index, &ingress_port, &fcoe,
-			    &eop, &sop, &rss_type, &csum_not_calc, &rss_hash,
-			    &bytes_written, &packet_error, &vlan_stripped,
-			    &vlan_tci, &checksum, &fcoe_sof, &fcoe_fc_crc_ok,
-			    &fcoe_enc_error, &fcoe_eof, &tcp_udp_csum_ok, &udp,
-			    &tcp, &ipv4_csum_ok, &ipv6, &ipv4, &ipv4_fragment,
-			    &fcs_ok);
+	cq_enet_rq_desc_dec(cq_desc, &ingress_port,
+			    &fcoe, &eop, &sop, &rss_type, &csum_not_calc,
+			    &rss_hash, &bytes_written, &packet_error,
+			    &vlan_stripped, &vlan_tci, &checksum, &fcoe_sof,
+			    &fcoe_fc_crc_ok, &fcoe_enc_error, &fcoe_eof,
+			    &tcp_udp_csum_ok, &udp, &tcp, &ipv4_csum_ok, &ipv6,
+			    &ipv4, &ipv4_fragment, &fcs_ok);
 
 	if (enic_rq_pkt_error(rq, packet_error, fcs_ok, bytes_written))
 		return;
@@ -324,3 +328,56 @@ void enic_rq_indicate_buf(struct vnic_rq *rq, struct cq_desc *cq_desc,
 		rqstats->pkt_truncated++;
 	}
 }
+
+static void enic_rq_service(struct enic *enic, struct cq_enet_rq_desc *cq_desc,
+			    u8 type, u16 q_number, u16 completed_index)
+{
+	struct enic_rq_stats *rqstats = &enic->rq[q_number].stats;
+	struct vnic_rq *vrq = &enic->rq[q_number].vrq;
+	struct vnic_rq_buf *vrq_buf = vrq->to_clean;
+	int skipped;
+
+	while (1) {
+		skipped = (vrq_buf->index != completed_index);
+		if (!skipped)
+			enic_rq_indicate_buf(enic, vrq, vrq_buf, cq_desc, type,
+					     q_number, completed_index);
+		else
+			rqstats->desc_skip++;
+
+		vrq->ring.desc_avail++;
+		vrq->to_clean = vrq_buf->next;
+		vrq_buf = vrq_buf->next;
+		if (!skipped)
+			break;
+	}
+}
+
+unsigned int enic_rq_cq_service(struct enic *enic, unsigned int cq_index,
+				unsigned int work_to_do)
+{
+	struct vnic_cq *cq = &enic->cq[cq_index];
+	struct cq_enet_rq_desc *cq_desc;
+	u16 q_number, completed_index;
+	unsigned int work_done = 0;
+	u8 type, color;
+
+	cq_desc = (struct cq_enet_rq_desc *)vnic_cq_to_clean(cq);
+
+	enic_rq_cq_desc_dec(cq_desc,  &type, &color, &q_number,
+			    &completed_index);
+
+	while (color != cq->last_color) {
+		enic_rq_service(enic, cq_desc, type, q_number, completed_index);
+		vnic_cq_inc_to_clean(cq);
+
+		if (++work_done >= work_to_do)
+			break;
+
+		cq_desc = (struct cq_enet_rq_desc *)vnic_cq_to_clean(cq);
+		enic_rq_cq_desc_dec(cq_desc, &type, &color, &q_number,
+				    &completed_index);
+	}
+
+	return work_done;
+}

drivers/net/ethernet/cisco/enic/enic_rq.h

@@ -2,9 +2,7 @@
  * Copyright 2024 Cisco Systems, Inc.  All rights reserved.
  */
 
-int enic_rq_service(struct vnic_dev *vdev, struct cq_desc *cq_desc, u8 type,
-		    u16 q_number, u16 completed_index, void *opaque);
-void enic_rq_indicate_buf(struct vnic_rq *rq, struct cq_desc *cq_desc,
-			  struct vnic_rq_buf *buf, int skipped, void *opaque);
+unsigned int enic_rq_cq_service(struct enic *enic, unsigned int cq_index,
+				unsigned int work_to_do);
 int enic_rq_alloc_buf(struct vnic_rq *rq);
 void enic_free_rq_buf(struct vnic_rq *rq, struct vnic_rq_buf *buf);

drivers/net/ethernet/cisco/enic/vnic_cq.h

@@ -97,6 +97,20 @@ static inline unsigned int vnic_cq_service(struct vnic_cq *cq,
 	return work_done;
 }
 
+static inline void *vnic_cq_to_clean(struct vnic_cq *cq)
+{
+	return ((u8 *)cq->ring.descs + cq->ring.desc_size * cq->to_clean);
+}
+
+static inline void vnic_cq_inc_to_clean(struct vnic_cq *cq)
+{
+	cq->to_clean++;
+	if (cq->to_clean == cq->ring.desc_count) {
+		cq->to_clean = 0;
+		cq->last_color = cq->last_color ? 0 : 1;
+	}
+}
+
 void vnic_cq_free(struct vnic_cq *cq);
 int vnic_cq_alloc(struct vnic_dev *vdev, struct vnic_cq *cq, unsigned int index,
 	unsigned int desc_count, unsigned int desc_size);