cxgb4: DB Drop Recovery for RDMA and LLD queues

recover LLD EQs for DB drop interrupts.  This includes adding a new
db_lock, a spin lock disabling BH too, used by the recovery thread and
the ring_tx_db() paths to allow db drop recovery.

Clean up initial DB avoidance code.

Add read_eq_indices() - this allows the LLD to use the PCIe mw to
efficiently read hw eq contexts.

Add cxgb4_sync_txq_pidx() - called by iw_cxgb4 to sync up the sw/hw
pidx value.

Add flush_eq_cache() and cxgb4_flush_eq_cache().  This allows iw_cxgb4
to flush the sge eq context cache before beginning db drop recovery.

Add module parameter, dbfoifo_int_thresh, to allow tuning the db
interrupt threshold value.

Add dbfifo_int_thresh to cxgb4_lld_info so iw_cxgb4 knows the threshold.

Add module parameter, dbfoifo_drain_delay, to allow tuning the amount
of time delay between DB FULL and EMPTY upcalls to iw_cxgb4.

Signed-off-by: Vipul Pandya <vipul@chelsio.com>
Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/net/ethernet/chelsio/cxgb4/cxgb4.h

@@ -51,6 +51,8 @@
 #define FW_VERSION_MINOR 1
 #define FW_VERSION_MICRO 0
 
+#define CH_WARN(adap, fmt, ...) dev_warn(adap->pdev_dev, fmt, ## __VA_ARGS__)
+
 enum {
 	MAX_NPORTS = 4,     /* max # of ports */
 	SERNUM_LEN = 24,    /* Serial # length */
@@ -64,6 +66,15 @@ enum {
 	MEM_MC
 };
 
+enum {
+	MEMWIN0_APERTURE = 65536,
+	MEMWIN0_BASE     = 0x30000,
+	MEMWIN1_APERTURE = 32768,
+	MEMWIN1_BASE     = 0x28000,
+	MEMWIN2_APERTURE = 2048,
+	MEMWIN2_BASE     = 0x1b800,
+};
+
 enum dev_master {
 	MASTER_CANT,
 	MASTER_MAY,
@@ -403,6 +414,9 @@ struct sge_txq {
 	struct tx_sw_desc *sdesc;   /* address of SW Tx descriptor ring */
 	struct sge_qstat *stat;     /* queue status entry */
 	dma_addr_t    phys_addr;    /* physical address of the ring */
+	spinlock_t db_lock;
+	int db_disabled;
+	unsigned short db_pidx;
 };
 
 struct sge_eth_txq {                /* state for an SGE Ethernet Tx queue */
@@ -475,6 +489,7 @@ struct adapter {
 	void __iomem *regs;
 	struct pci_dev *pdev;
 	struct device *pdev_dev;
+	unsigned int mbox;
 	unsigned int fn;
 	unsigned int flags;
 
@@ -607,6 +622,7 @@ irqreturn_t t4_sge_intr_msix(int irq, void *cookie);
 void t4_sge_init(struct adapter *adap);
 void t4_sge_start(struct adapter *adap);
 void t4_sge_stop(struct adapter *adap);
+extern int dbfifo_int_thresh;
 
 #define for_each_port(adapter, iter) \
 	for (iter = 0; iter < (adapter)->params.nports; ++iter)

drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c

@@ -148,15 +148,6 @@ static unsigned int pfvfres_pmask(struct adapter *adapter,
 }
 #endif
 
-enum {
-	MEMWIN0_APERTURE = 65536,
-	MEMWIN0_BASE     = 0x30000,
-	MEMWIN1_APERTURE = 32768,
-	MEMWIN1_BASE     = 0x28000,
-	MEMWIN2_APERTURE = 2048,
-	MEMWIN2_BASE     = 0x1b800,
-};
-
 enum {
 	MAX_TXQ_ENTRIES      = 16384,
 	MAX_CTRL_TXQ_ENTRIES = 1024,
@@ -371,6 +362,15 @@ static int set_addr_filters(const struct net_device *dev, bool sleep)
 				uhash | mhash, sleep);
 }
 
+int dbfifo_int_thresh = 10; /* 10 == 640 entry threshold */
+module_param(dbfifo_int_thresh, int, 0644);
+MODULE_PARM_DESC(dbfifo_int_thresh, "doorbell fifo interrupt threshold");
+
+int dbfifo_drain_delay = 1000; /* usecs to sleep while draining the dbfifo */
+module_param(dbfifo_drain_delay, int, 0644);
+MODULE_PARM_DESC(dbfifo_drain_delay,
+		 "usecs to sleep while draining the dbfifo");
+
 /*
  * Set Rx properties of a port, such as promiscruity, address filters, and MTU.
  * If @mtu is -1 it is left unchanged.
@@ -389,6 +389,8 @@ static int set_rxmode(struct net_device *dev, int mtu, bool sleep_ok)
 	return ret;
 }
 
+static struct workqueue_struct *workq;
+
 /**
  *	link_start - enable a port
  *	@dev: the port to enable
@@ -2196,7 +2198,7 @@ static void cxgb4_queue_tid_release(struct tid_info *t, unsigned int chan,
 	adap->tid_release_head = (void **)((uintptr_t)p | chan);
 	if (!adap->tid_release_task_busy) {
 		adap->tid_release_task_busy = true;
-		schedule_work(&adap->tid_release_task);
+		queue_work(workq, &adap->tid_release_task);
 	}
 	spin_unlock_bh(&adap->tid_release_lock);
 }
@@ -2423,6 +2425,59 @@ void cxgb4_iscsi_init(struct net_device *dev, unsigned int tag_mask,
 }
 EXPORT_SYMBOL(cxgb4_iscsi_init);
 
+int cxgb4_flush_eq_cache(struct net_device *dev)
+{
+	struct adapter *adap = netdev2adap(dev);
+	int ret;
+
+	ret = t4_fwaddrspace_write(adap, adap->mbox,
+				   0xe1000000 + A_SGE_CTXT_CMD, 0x20000000);
+	return ret;
+}
+EXPORT_SYMBOL(cxgb4_flush_eq_cache);
+
+static int read_eq_indices(struct adapter *adap, u16 qid, u16 *pidx, u16 *cidx)
+{
+	u32 addr = t4_read_reg(adap, A_SGE_DBQ_CTXT_BADDR) + 24 * qid + 8;
+	__be64 indices;
+	int ret;
+
+	ret = t4_mem_win_read_len(adap, addr, (__be32 *)&indices, 8);
+	if (!ret) {
+		indices = be64_to_cpu(indices);
+		*cidx = (indices >> 25) & 0xffff;
+		*pidx = (indices >> 9) & 0xffff;
+	}
+	return ret;
+}
+
+int cxgb4_sync_txq_pidx(struct net_device *dev, u16 qid, u16 pidx,
+			u16 size)
+{
+	struct adapter *adap = netdev2adap(dev);
+	u16 hw_pidx, hw_cidx;
+	int ret;
+
+	ret = read_eq_indices(adap, qid, &hw_pidx, &hw_cidx);
+	if (ret)
+		goto out;
+
+	if (pidx != hw_pidx) {
+		u16 delta;
+
+		if (pidx >= hw_pidx)
+			delta = pidx - hw_pidx;
+		else
+			delta = size - hw_pidx + pidx;
+		wmb();
+		t4_write_reg(adap, MYPF_REG(A_SGE_PF_KDOORBELL),
+			     V_QID(qid) | V_PIDX(delta));
+	}
+out:
+	return ret;
+}
+EXPORT_SYMBOL(cxgb4_sync_txq_pidx);
+
 static struct pci_driver cxgb4_driver;
 
 static void check_neigh_update(struct neighbour *neigh)
@@ -2456,6 +2511,95 @@ static struct notifier_block cxgb4_netevent_nb = {
 	.notifier_call = netevent_cb
 };
 
+static void drain_db_fifo(struct adapter *adap, int usecs)
+{
+	u32 v;
+
+	do {
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		schedule_timeout(usecs_to_jiffies(usecs));
+		v = t4_read_reg(adap, A_SGE_DBFIFO_STATUS);
+		if (G_LP_COUNT(v) == 0 && G_HP_COUNT(v) == 0)
+			break;
+	} while (1);
+}
+
+static void disable_txq_db(struct sge_txq *q)
+{
+	spin_lock_irq(&q->db_lock);
+	q->db_disabled = 1;
+	spin_unlock_irq(&q->db_lock);
+}
+
+static void enable_txq_db(struct sge_txq *q)
+{
+	spin_lock_irq(&q->db_lock);
+	q->db_disabled = 0;
+	spin_unlock_irq(&q->db_lock);
+}
+
+static void disable_dbs(struct adapter *adap)
+{
+	int i;
+
+	for_each_ethrxq(&adap->sge, i)
+		disable_txq_db(&adap->sge.ethtxq[i].q);
+	for_each_ofldrxq(&adap->sge, i)
+		disable_txq_db(&adap->sge.ofldtxq[i].q);
+	for_each_port(adap, i)
+		disable_txq_db(&adap->sge.ctrlq[i].q);
+}
+
+static void enable_dbs(struct adapter *adap)
+{
+	int i;
+
+	for_each_ethrxq(&adap->sge, i)
+		enable_txq_db(&adap->sge.ethtxq[i].q);
+	for_each_ofldrxq(&adap->sge, i)
+		enable_txq_db(&adap->sge.ofldtxq[i].q);
+	for_each_port(adap, i)
+		enable_txq_db(&adap->sge.ctrlq[i].q);
+}
+
+static void sync_txq_pidx(struct adapter *adap, struct sge_txq *q)
+{
+	u16 hw_pidx, hw_cidx;
+	int ret;
+
+	spin_lock_bh(&q->db_lock);
+	ret = read_eq_indices(adap, (u16)q->cntxt_id, &hw_pidx, &hw_cidx);
+	if (ret)
+		goto out;
+	if (q->db_pidx != hw_pidx) {
+		u16 delta;
+
+		if (q->db_pidx >= hw_pidx)
+			delta = q->db_pidx - hw_pidx;
+		else
+			delta = q->size - hw_pidx + q->db_pidx;
+		wmb();
+		t4_write_reg(adap, MYPF_REG(A_SGE_PF_KDOORBELL),
+				V_QID(q->cntxt_id) | V_PIDX(delta));
+	}
+out:
+	q->db_disabled = 0;
+	spin_unlock_bh(&q->db_lock);
+	if (ret)
+		CH_WARN(adap, "DB drop recovery failed.\n");
+}
+static void recover_all_queues(struct adapter *adap)
+{
+	int i;
+
+	for_each_ethrxq(&adap->sge, i)
+		sync_txq_pidx(adap, &adap->sge.ethtxq[i].q);
+	for_each_ofldrxq(&adap->sge, i)
+		sync_txq_pidx(adap, &adap->sge.ofldtxq[i].q);
+	for_each_port(adap, i)
+		sync_txq_pidx(adap, &adap->sge.ctrlq[i].q);
+}
+
 static void notify_rdma_uld(struct adapter *adap, enum cxgb4_control cmd)
 {
 	mutex_lock(&uld_mutex);
@@ -2468,55 +2612,41 @@ static void notify_rdma_uld(struct adapter *adap, enum cxgb4_control cmd)
 static void process_db_full(struct work_struct *work)
 {
 	struct adapter *adap;
-	static int delay = 1000;
-	u32 v;
 
 	adap = container_of(work, struct adapter, db_full_task);
 
-
-	/* stop LLD queues */
-
 	notify_rdma_uld(adap, CXGB4_CONTROL_DB_FULL);
-	do {
+	drain_db_fifo(adap, dbfifo_drain_delay);
-		set_current_state(TASK_UNINTERRUPTIBLE);
+	t4_set_reg_field(adap, A_SGE_INT_ENABLE3,
-		schedule_timeout(usecs_to_jiffies(delay));
+			F_DBFIFO_HP_INT | F_DBFIFO_LP_INT,
-		v = t4_read_reg(adap, A_SGE_DBFIFO_STATUS);
+			F_DBFIFO_HP_INT | F_DBFIFO_LP_INT);
-		if (G_LP_COUNT(v) == 0 && G_HP_COUNT(v) == 0)
-			break;
-	} while (1);
 	notify_rdma_uld(adap, CXGB4_CONTROL_DB_EMPTY);
-
-
-	/*
-	 * The more we get db full interrupts, the more we'll delay
-	 * in re-enabling db rings on queues, capped off at 200ms.
-	 */
-	delay = min(delay << 1, 200000);
-
-	/* resume LLD queues */
 }
 
 static void process_db_drop(struct work_struct *work)
 {
 	struct adapter *adap;
+
 	adap = container_of(work, struct adapter, db_drop_task);
 
-
+	t4_set_reg_field(adap, A_SGE_DOORBELL_CONTROL, F_DROPPED_DB, 0);
-	/*
+	disable_dbs(adap);
-	 * sync the PIDX values in HW and SW for LLD queues.
-	 */
-
 	notify_rdma_uld(adap, CXGB4_CONTROL_DB_DROP);
+	drain_db_fifo(adap, 1);
+	recover_all_queues(adap);
+	enable_dbs(adap);
 }
 
 void t4_db_full(struct adapter *adap)
 {
-	schedule_work(&adap->db_full_task);
+	t4_set_reg_field(adap, A_SGE_INT_ENABLE3,
+			F_DBFIFO_HP_INT | F_DBFIFO_LP_INT, 0);
+	queue_work(workq, &adap->db_full_task);
 }
 
 void t4_db_dropped(struct adapter *adap)
 {
-	schedule_work(&adap->db_drop_task);
+	queue_work(workq, &adap->db_drop_task);
 }
 
 static void uld_attach(struct adapter *adap, unsigned int uld)
@@ -2552,6 +2682,7 @@ static void uld_attach(struct adapter *adap, unsigned int uld)
 	lli.gts_reg = adap->regs + MYPF_REG(SGE_PF_GTS);
 	lli.db_reg = adap->regs + MYPF_REG(SGE_PF_KDOORBELL);
 	lli.fw_vers = adap->params.fw_vers;
+	lli.dbfifo_int_thresh = dbfifo_int_thresh;
 
 	handle = ulds[uld].add(&lli);
 	if (IS_ERR(handle)) {
@@ -3668,6 +3799,7 @@ static int __devinit init_one(struct pci_dev *pdev,
 
 	adapter->pdev = pdev;
 	adapter->pdev_dev = &pdev->dev;
+	adapter->mbox = func;
 	adapter->fn = func;
 	adapter->msg_enable = dflt_msg_enable;
 	memset(adapter->chan_map, 0xff, sizeof(adapter->chan_map));
@@ -3865,6 +3997,10 @@ static int __init cxgb4_init_module(void)
 {
 	int ret;
 
+	workq = create_singlethread_workqueue("cxgb4");
+	if (!workq)
+		return -ENOMEM;
+
 	/* Debugfs support is optional, just warn if this fails */
 	cxgb4_debugfs_root = debugfs_create_dir(KBUILD_MODNAME, NULL);
 	if (!cxgb4_debugfs_root)
@@ -3880,6 +4016,8 @@ static void __exit cxgb4_cleanup_module(void)
 {
 	pci_unregister_driver(&cxgb4_driver);
 	debugfs_remove(cxgb4_debugfs_root);  /* NULL ok */
+	flush_workqueue(workq);
+	destroy_workqueue(workq);
 }
 
 module_init(cxgb4_init_module);

drivers/net/ethernet/chelsio/cxgb4/cxgb4_uld.h

@@ -218,6 +218,7 @@ struct cxgb4_lld_info {
 	unsigned short ucq_density;          /* # of user CQs/page */
 	void __iomem *gts_reg;               /* address of GTS register */
 	void __iomem *db_reg;                /* address of kernel doorbell */
+	int dbfifo_int_thresh;		     /* doorbell fifo int threshold */
 };
 
 struct cxgb4_uld_info {
@@ -226,6 +227,7 @@ struct cxgb4_uld_info {
 	int (*rx_handler)(void *handle, const __be64 *rsp,
 			  const struct pkt_gl *gl);
 	int (*state_change)(void *handle, enum cxgb4_state new_state);
+	int (*control)(void *handle, enum cxgb4_control control, ...);
 };
 
 int cxgb4_register_uld(enum cxgb4_uld type, const struct cxgb4_uld_info *p);
@@ -243,4 +245,6 @@ void cxgb4_iscsi_init(struct net_device *dev, unsigned int tag_mask,
 		      const unsigned int *pgsz_order);
 struct sk_buff *cxgb4_pktgl_to_skb(const struct pkt_gl *gl,
 				   unsigned int skb_len, unsigned int pull_len);
+int cxgb4_sync_txq_pidx(struct net_device *dev, u16 qid, u16 pidx, u16 size);
+int cxgb4_flush_eq_cache(struct net_device *dev);
 #endif  /* !__CXGB4_OFLD_H */

drivers/net/ethernet/chelsio/cxgb4/sge.c

@@ -767,8 +767,13 @@ static void write_sgl(const struct sk_buff *skb, struct sge_txq *q,
 static inline void ring_tx_db(struct adapter *adap, struct sge_txq *q, int n)
 {
 	wmb();            /* write descriptors before telling HW */
-	t4_write_reg(adap, MYPF_REG(SGE_PF_KDOORBELL),
+	spin_lock(&q->db_lock);
-		     QID(q->cntxt_id) | PIDX(n));
+	if (!q->db_disabled) {
+		t4_write_reg(adap, MYPF_REG(A_SGE_PF_KDOORBELL),
+			     V_QID(q->cntxt_id) | V_PIDX(n));
+	}
+	q->db_pidx = q->pidx;
+	spin_unlock(&q->db_lock);
 }
 
 /**
@@ -2081,6 +2086,7 @@ static void init_txq(struct adapter *adap, struct sge_txq *q, unsigned int id)
 	q->stops = q->restarts = 0;
 	q->stat = (void *)&q->desc[q->size];
 	q->cntxt_id = id;
+	spin_lock_init(&q->db_lock);
 	adap->sge.egr_map[id - adap->sge.egr_start] = q;
 }
 
@@ -2415,9 +2421,15 @@ void t4_sge_init(struct adapter *adap)
 			 RXPKTCPLMODE |
 			 (STAT_LEN == 128 ? EGRSTATUSPAGESIZE : 0));
 
+	/*
+	 * Set up to drop DOORBELL writes when the DOORBELL FIFO overflows
+	 * and generate an interrupt when this occurs so we can recover.
+	 */
 	t4_set_reg_field(adap, A_SGE_DBFIFO_STATUS,
-			V_HP_INT_THRESH(5) | V_LP_INT_THRESH(5),
+			V_HP_INT_THRESH(M_HP_INT_THRESH) |
-			V_HP_INT_THRESH(5) | V_LP_INT_THRESH(5));
+			V_LP_INT_THRESH(M_LP_INT_THRESH),
+			V_HP_INT_THRESH(dbfifo_int_thresh) |
+			V_LP_INT_THRESH(dbfifo_int_thresh));
 	t4_set_reg_field(adap, A_SGE_DOORBELL_CONTROL, F_ENABLE_DROP,
 			F_ENABLE_DROP);
 

drivers/net/ethernet/chelsio/cxgb4/t4_regs.h

@@ -190,6 +190,59 @@
 #define SGE_DEBUG_DATA_LOW 0x10d4
 #define SGE_INGRESS_QUEUES_PER_PAGE_PF 0x10f4
 
+#define S_LP_INT_THRESH    12
+#define V_LP_INT_THRESH(x) ((x) << S_LP_INT_THRESH)
+#define S_HP_INT_THRESH    28
+#define V_HP_INT_THRESH(x) ((x) << S_HP_INT_THRESH)
+#define A_SGE_DBFIFO_STATUS 0x10a4
+
+#define S_ENABLE_DROP    13
+#define V_ENABLE_DROP(x) ((x) << S_ENABLE_DROP)
+#define F_ENABLE_DROP    V_ENABLE_DROP(1U)
+#define A_SGE_DOORBELL_CONTROL 0x10a8
+
+#define A_SGE_CTXT_CMD 0x11fc
+#define A_SGE_DBQ_CTXT_BADDR 0x1084
+
+#define A_SGE_PF_KDOORBELL 0x0
+
+#define S_QID 15
+#define V_QID(x) ((x) << S_QID)
+
+#define S_PIDX 0
+#define V_PIDX(x) ((x) << S_PIDX)
+
+#define M_LP_COUNT 0x7ffU
+#define S_LP_COUNT 0
+#define G_LP_COUNT(x) (((x) >> S_LP_COUNT) & M_LP_COUNT)
+
+#define M_HP_COUNT 0x7ffU
+#define S_HP_COUNT 16
+#define G_HP_COUNT(x) (((x) >> S_HP_COUNT) & M_HP_COUNT)
+
+#define A_SGE_INT_ENABLE3 0x1040
+
+#define S_DBFIFO_HP_INT 8
+#define V_DBFIFO_HP_INT(x) ((x) << S_DBFIFO_HP_INT)
+#define F_DBFIFO_HP_INT V_DBFIFO_HP_INT(1U)
+
+#define S_DBFIFO_LP_INT 7
+#define V_DBFIFO_LP_INT(x) ((x) << S_DBFIFO_LP_INT)
+#define F_DBFIFO_LP_INT V_DBFIFO_LP_INT(1U)
+
+#define S_DROPPED_DB 0
+#define V_DROPPED_DB(x) ((x) << S_DROPPED_DB)
+#define F_DROPPED_DB V_DROPPED_DB(1U)
+
+#define S_ERR_DROPPED_DB 18
+#define V_ERR_DROPPED_DB(x) ((x) << S_ERR_DROPPED_DB)
+#define F_ERR_DROPPED_DB V_ERR_DROPPED_DB(1U)
+
+#define A_PCIE_MEM_ACCESS_OFFSET 0x306c
+
+#define M_HP_INT_THRESH 0xfU
+#define M_LP_INT_THRESH 0xfU
+
 #define PCIE_PF_CLI 0x44
 #define PCIE_INT_CAUSE 0x3004
 #define  UNXSPLCPLERR  0x20000000U

drivers/net/ethernet/chelsio/cxgb4/t4fw_api.h

@@ -1620,4 +1620,19 @@ struct fw_hdr {
 #define FW_HDR_FW_VER_MINOR_GET(x) (((x) >> 16) & 0xff)
 #define FW_HDR_FW_VER_MICRO_GET(x) (((x) >> 8) & 0xff)
 #define FW_HDR_FW_VER_BUILD_GET(x) (((x) >> 0) & 0xff)
+
+#define S_FW_CMD_OP 24
+#define V_FW_CMD_OP(x) ((x) << S_FW_CMD_OP)
+
+#define S_FW_CMD_REQUEST 23
+#define V_FW_CMD_REQUEST(x) ((x) << S_FW_CMD_REQUEST)
+#define F_FW_CMD_REQUEST V_FW_CMD_REQUEST(1U)
+
+#define S_FW_CMD_WRITE 21
+#define V_FW_CMD_WRITE(x) ((x) << S_FW_CMD_WRITE)
+#define F_FW_CMD_WRITE V_FW_CMD_WRITE(1U)
+
+#define S_FW_LDST_CMD_ADDRSPACE 0
+#define V_FW_LDST_CMD_ADDRSPACE(x) ((x) << S_FW_LDST_CMD_ADDRSPACE)
+
 #endif /* _T4FW_INTERFACE_H_ */