net/mlx5: Reimplement write combining test

The test of write combining was added before in mlx5_ib driver. It
opens UD QP and posts NOP WQEs, and uses BlueFlame doorbell. When
BlueFlame is used, WQEs get written directly to a PCI BAR of the
device (in addition to memory) so that the device handles them without
having to access memory.

In this test, the WQEs written in memory are different from the ones
written to the BlueFlame which request CQE update. By checking the
completion reports posted on CQ, we can know if BlueFlame succeeds or
not. The write combining must be supported if BlueFlame succeeds as
its register is written using write combining.

This patch reimplements the test in the same way, but using a pair of
SQ and CQ only. It is moved to mlx5_core as a general feature used by
both mlx5_core and mlx5_ib.

Besides, save write combine test result of the PCI function, so that
its thousands of child functions such as SF can query without paying
the time and resource penalty by itself. The test function is called
only after failing to get the cached result. With this enhancement,
all thousands of SFs of the PF attached to same driver no longer need
to perform WC check explicitly, which is already done in the system.
This saves several commands per SF, thereby speeds up SF creation and
also saves completion EQ creation.
Signed-off-by: Jianbo Liu <jianbol@nvidia.com>
Reviewed-by: Tariq Toukan <tariqt@nvidia.com>
Link: https://lore.kernel.org/r/4ff5a8cc4c5b5b0d98397baa45a5019bcdbf096e.1717409369.git.leon@kernel.orgSigned-off-by: Leon Romanovsky <leon@kernel.org>

drivers/infiniband/hw/mlx5/main.c

@@ -1810,7 +1810,7 @@ static int set_ucontext_resp(struct ib_ucontext *uctx,
 	}
 
 	resp->qp_tab_size = 1 << MLX5_CAP_GEN(dev->mdev, log_max_qp);
-	if (dev->wc_support)
+	if (mlx5_wc_support_get(dev->mdev))
 		resp->bf_reg_size = 1 << MLX5_CAP_GEN(dev->mdev,
 						      log_bf_reg_size);
 	resp->cache_line_size = cache_line_size();
@@ -2337,7 +2337,7 @@ static int mlx5_ib_mmap(struct ib_ucontext *ibcontext, struct vm_area_struct *vm
 	switch (command) {
 	case MLX5_IB_MMAP_WC_PAGE:
 	case MLX5_IB_MMAP_ALLOC_WC:
-		if (!dev->wc_support)
+		if (!mlx5_wc_support_get(dev->mdev))
 			return -EPERM;
 		fallthrough;
 	case MLX5_IB_MMAP_NC_PAGE:
@@ -3612,7 +3612,7 @@ static int UVERBS_HANDLER(MLX5_IB_METHOD_UAR_OBJ_ALLOC)(
 	    alloc_type != MLX5_IB_UAPI_UAR_ALLOC_TYPE_NC)
 		return -EOPNOTSUPP;
 
-	if (!to_mdev(c->ibucontext.device)->wc_support &&
+	if (!mlx5_wc_support_get(to_mdev(c->ibucontext.device)->mdev) &&
 	    alloc_type == MLX5_IB_UAPI_UAR_ALLOC_TYPE_BF)
 		return -EOPNOTSUPP;
 
@@ -3766,18 +3766,6 @@ static int mlx5_ib_stage_init_init(struct mlx5_ib_dev *dev)
 	return err;
 }
 
-static int mlx5_ib_enable_driver(struct ib_device *dev)
-{
-	struct mlx5_ib_dev *mdev = to_mdev(dev);
-	int ret;
-
-	ret = mlx5_ib_test_wc(mdev);
-	mlx5_ib_dbg(mdev, "Write-Combining %s",
-		    mdev->wc_support ? "supported" : "not supported");
-
-	return ret;
-}
-
 static const struct ib_device_ops mlx5_ib_dev_ops = {
 	.owner = THIS_MODULE,
 	.driver_id = RDMA_DRIVER_MLX5,
@@ -3808,7 +3796,6 @@ static const struct ib_device_ops mlx5_ib_dev_ops = {
 	.drain_rq = mlx5_ib_drain_rq,
 	.drain_sq = mlx5_ib_drain_sq,
 	.device_group = &mlx5_attr_group,
-	.enable_driver = mlx5_ib_enable_driver,
 	.get_dev_fw_str = get_dev_fw_str,
 	.get_dma_mr = mlx5_ib_get_dma_mr,
 	.get_link_layer = mlx5_ib_port_link_layer,

drivers/infiniband/hw/mlx5/mem.c

@@ -30,10 +30,8 @@
  * SOFTWARE.
  */
 
-#include <linux/io.h>
 #include <rdma/ib_umem_odp.h>
 #include "mlx5_ib.h"
-#include <linux/jiffies.h>
 
 /*
  * Fill in a physical address list. ib_umem_num_dma_blocks() entries will be
@@ -95,199 +93,3 @@ unsigned long __mlx5_umem_find_best_quantized_pgoff(
 		return 0;
 	return page_size;
 }
-
-#define WR_ID_BF 0xBF
-#define WR_ID_END 0xBAD
-#define TEST_WC_NUM_WQES 255
-#define TEST_WC_POLLING_MAX_TIME_JIFFIES msecs_to_jiffies(100)
-static int post_send_nop(struct mlx5_ib_dev *dev, struct ib_qp *ibqp, u64 wr_id,
-			 bool signaled)
-{
-	struct mlx5_ib_qp *qp = to_mqp(ibqp);
-	struct mlx5_wqe_ctrl_seg *ctrl;
-	struct mlx5_bf *bf = &qp->bf;
-	__be32 mmio_wqe[16] = {};
-	unsigned long flags;
-	unsigned int idx;
-
-	if (unlikely(dev->mdev->state == MLX5_DEVICE_STATE_INTERNAL_ERROR))
-		return -EIO;
-
-	spin_lock_irqsave(&qp->sq.lock, flags);
-
-	idx = qp->sq.cur_post & (qp->sq.wqe_cnt - 1);
-	ctrl = mlx5_frag_buf_get_wqe(&qp->sq.fbc, idx);
-
-	memset(ctrl, 0, sizeof(struct mlx5_wqe_ctrl_seg));
-	ctrl->fm_ce_se = signaled ? MLX5_WQE_CTRL_CQ_UPDATE : 0;
-	ctrl->opmod_idx_opcode =
-		cpu_to_be32(((u32)(qp->sq.cur_post) << 8) | MLX5_OPCODE_NOP);
-	ctrl->qpn_ds = cpu_to_be32((sizeof(struct mlx5_wqe_ctrl_seg) / 16) |
-				   (qp->trans_qp.base.mqp.qpn << 8));
-
-	qp->sq.wrid[idx] = wr_id;
-	qp->sq.w_list[idx].opcode = MLX5_OPCODE_NOP;
-	qp->sq.wqe_head[idx] = qp->sq.head + 1;
-	qp->sq.cur_post += DIV_ROUND_UP(sizeof(struct mlx5_wqe_ctrl_seg),
-					MLX5_SEND_WQE_BB);
-	qp->sq.w_list[idx].next = qp->sq.cur_post;
-	qp->sq.head++;
-
-	memcpy(mmio_wqe, ctrl, sizeof(*ctrl));
-	((struct mlx5_wqe_ctrl_seg *)&mmio_wqe)->fm_ce_se |=
-		MLX5_WQE_CTRL_CQ_UPDATE;
-
-	/* Make sure that descriptors are written before
-	 * updating doorbell record and ringing the doorbell
-	 */
-	wmb();
-
-	qp->db.db[MLX5_SND_DBR] = cpu_to_be32(qp->sq.cur_post);
-
-	/* Make sure doorbell record is visible to the HCA before
-	 * we hit doorbell
-	 */
-	wmb();
-	__iowrite64_copy(bf->bfreg->map + bf->offset, mmio_wqe,
-			 sizeof(mmio_wqe) / 8);
-
-	bf->offset ^= bf->buf_size;
-
-	spin_unlock_irqrestore(&qp->sq.lock, flags);
-
-	return 0;
-}
-
-static int test_wc_poll_cq_result(struct mlx5_ib_dev *dev, struct ib_cq *cq)
-{
-	int ret;
-	struct ib_wc wc = {};
-	unsigned long end = jiffies + TEST_WC_POLLING_MAX_TIME_JIFFIES;
-
-	do {
-		ret = ib_poll_cq(cq, 1, &wc);
-		if (ret < 0 || wc.status)
-			return ret < 0 ? ret : -EINVAL;
-		if (ret)
-			break;
-	} while (!time_after(jiffies, end));
-
-	if (!ret)
-		return -ETIMEDOUT;
-
-	if (wc.wr_id != WR_ID_BF)
-		ret = 0;
-
-	return ret;
-}
-
-static int test_wc_do_send(struct mlx5_ib_dev *dev, struct ib_qp *qp)
-{
-	int err, i;
-
-	for (i = 0; i < TEST_WC_NUM_WQES; i++) {
-		err = post_send_nop(dev, qp, WR_ID_BF, false);
-		if (err)
-			return err;
-	}
-
-	return post_send_nop(dev, qp, WR_ID_END, true);
-}
-
-int mlx5_ib_test_wc(struct mlx5_ib_dev *dev)
-{
-	struct ib_cq_init_attr cq_attr = { .cqe = TEST_WC_NUM_WQES + 1 };
-	int port_type_cap = MLX5_CAP_GEN(dev->mdev, port_type);
-	struct ib_qp_init_attr qp_init_attr = {
-		.cap = { .max_send_wr = TEST_WC_NUM_WQES },
-		.qp_type = IB_QPT_UD,
-		.sq_sig_type = IB_SIGNAL_REQ_WR,
-		.create_flags = MLX5_IB_QP_CREATE_WC_TEST,
-	};
-	struct ib_qp_attr qp_attr = { .port_num = 1 };
-	struct ib_device *ibdev = &dev->ib_dev;
-	struct ib_qp *qp;
-	struct ib_cq *cq;
-	struct ib_pd *pd;
-	int ret;
-
-	if (!MLX5_CAP_GEN(dev->mdev, bf))
-		return 0;
-
-	if (!dev->mdev->roce.roce_en &&
-	    port_type_cap == MLX5_CAP_PORT_TYPE_ETH) {
-		if (mlx5_core_is_pf(dev->mdev))
-			dev->wc_support = arch_can_pci_mmap_wc();
-		return 0;
-	}
-
-	ret = mlx5_alloc_bfreg(dev->mdev, &dev->wc_bfreg, true, false);
-	if (ret)
-		goto print_err;
-
-	if (!dev->wc_bfreg.wc)
-		goto out1;
-
-	pd = ib_alloc_pd(ibdev, 0);
-	if (IS_ERR(pd)) {
-		ret = PTR_ERR(pd);
-		goto out1;
-	}
-
-	cq = ib_create_cq(ibdev, NULL, NULL, NULL, &cq_attr);
-	if (IS_ERR(cq)) {
-		ret = PTR_ERR(cq);
-		goto out2;
-	}
-
-	qp_init_attr.recv_cq = cq;
-	qp_init_attr.send_cq = cq;
-	qp = ib_create_qp(pd, &qp_init_attr);
-	if (IS_ERR(qp)) {
-		ret = PTR_ERR(qp);
-		goto out3;
-	}
-
-	qp_attr.qp_state = IB_QPS_INIT;
-	ret = ib_modify_qp(qp, &qp_attr,
-			   IB_QP_STATE | IB_QP_PORT | IB_QP_PKEY_INDEX |
-				   IB_QP_QKEY);
-	if (ret)
-		goto out4;
-
-	qp_attr.qp_state = IB_QPS_RTR;
-	ret = ib_modify_qp(qp, &qp_attr, IB_QP_STATE);
-	if (ret)
-		goto out4;
-
-	qp_attr.qp_state = IB_QPS_RTS;
-	ret = ib_modify_qp(qp, &qp_attr, IB_QP_STATE | IB_QP_SQ_PSN);
-	if (ret)
-		goto out4;
-
-	ret = test_wc_do_send(dev, qp);
-	if (ret < 0)
-		goto out4;
-
-	ret = test_wc_poll_cq_result(dev, cq);
-	if (ret > 0) {
-		dev->wc_support = true;
-		ret = 0;
-	}
-
-out4:
-	ib_destroy_qp(qp);
-out3:
-	ib_destroy_cq(cq);
-out2:
-	ib_dealloc_pd(pd);
-out1:
-	mlx5_free_bfreg(dev->mdev, &dev->wc_bfreg);
-print_err:
-	if (ret)
-		mlx5_ib_err(
-			dev,
-			"Error %d while trying to test write-combining support\n",
-			ret);
-	return ret;
-}

drivers/infiniband/hw/mlx5/mlx5_ib.h

@@ -341,7 +341,6 @@ struct mlx5_ib_flow_db {
  * rely on the range reserved for that use in the ib_qp_create_flags enum.
  */
 #define MLX5_IB_QP_CREATE_SQPN_QP1	IB_QP_CREATE_RESERVED_START
-#define MLX5_IB_QP_CREATE_WC_TEST	(IB_QP_CREATE_RESERVED_START << 1)
 
 struct wr_list {
 	u16	opcode;
@@ -1123,7 +1122,6 @@ struct mlx5_ib_dev {
 	u8				ib_active:1;
 	u8				is_rep:1;
 	u8				lag_active:1;
-	u8				wc_support:1;
 	u8				fill_delay;
 	struct umr_common		umrc;
 	/* sync used page count stats
@@ -1149,7 +1147,6 @@ struct mlx5_ib_dev {
 	/* Array with num_ports elements */
 	struct mlx5_ib_port	*port;
 	struct mlx5_sq_bfreg	bfreg;
-	struct mlx5_sq_bfreg	wc_bfreg;
 	struct mlx5_sq_bfreg	fp_bfreg;
 	struct mlx5_ib_delay_drop	delay_drop;
 	const struct mlx5_ib_profile	*profile;

drivers/infiniband/hw/mlx5/qp.c

@@ -1107,8 +1107,6 @@ static int _create_kernel_qp(struct mlx5_ib_dev *dev,
 
 	if (init_attr->qp_type == MLX5_IB_QPT_REG_UMR)
 		qp->bf.bfreg = &dev->fp_bfreg;
-	else if (qp->flags & MLX5_IB_QP_CREATE_WC_TEST)
-		qp->bf.bfreg = &dev->wc_bfreg;
 	else
 		qp->bf.bfreg = &dev->bfreg;
 
@@ -2959,14 +2957,6 @@ static void process_create_flag(struct mlx5_ib_dev *dev, int *flags, int flag,
 		return;
 	}
 
-	if (flag == MLX5_IB_QP_CREATE_WC_TEST) {
-		/*
-		 * Special case, if condition didn't meet, it won't be error,
-		 * just different in-kernel flow.
-		 */
-		*flags &= ~MLX5_IB_QP_CREATE_WC_TEST;
-		return;
-	}
 	mlx5_ib_dbg(dev, "Verbs create QP flag 0x%X is not supported\n", flag);
 }
 
@@ -3027,8 +3017,6 @@ static int process_create_flags(struct mlx5_ib_dev *dev, struct mlx5_ib_qp *qp,
 			    IB_QP_CREATE_PCI_WRITE_END_PADDING,
 			    MLX5_CAP_GEN(mdev, end_pad), qp);
 
-	process_create_flag(dev, &create_flags, MLX5_IB_QP_CREATE_WC_TEST,
-			    qp_type != MLX5_IB_QPT_REG_UMR, qp);
 	process_create_flag(dev, &create_flags, MLX5_IB_QP_CREATE_SQPN_QP1,
 			    true, qp);
 
@@ -4609,10 +4597,6 @@ static bool mlx5_ib_modify_qp_allowed(struct mlx5_ib_dev *dev,
 	if (qp->type == IB_QPT_RAW_PACKET || qp->type == MLX5_IB_QPT_REG_UMR)
 		return true;
 
-	/* Internal QP used for wc testing, with NOPs in wq */
-	if (qp->flags & MLX5_IB_QP_CREATE_WC_TEST)
-		return true;
-
 	return false;
 }
 

drivers/net/ethernet/mellanox/mlx5/core/Makefile

@@ -17,7 +17,7 @@ mlx5_core-y :=	main.o cmd.o debugfs.o fw.o eq.o uar.o pagealloc.o \
 		fs_counters.o fs_ft_pool.o rl.o lag/debugfs.o lag/lag.o dev.o events.o wq.o lib/gid.o \
 		lib/devcom.o lib/pci_vsc.o lib/dm.o lib/fs_ttc.o diag/fs_tracepoint.o \
 		diag/fw_tracer.o diag/crdump.o devlink.o diag/rsc_dump.o diag/reporter_vnic.o \
-		fw_reset.o qos.o lib/tout.o lib/aso.o
+		fw_reset.o qos.o lib/tout.o lib/aso.o wc.o
 
 #
 # Netdev basic

drivers/net/ethernet/mellanox/mlx5/core/main.c

@@ -1819,6 +1819,7 @@ int mlx5_mdev_init(struct mlx5_core_dev *dev, int profile_idx)
 	mutex_init(&dev->intf_state_mutex);
 	lockdep_set_class(&dev->intf_state_mutex, &dev->lock_key);
 	mutex_init(&dev->mlx5e_res.uplink_netdev_lock);
+	mutex_init(&dev->wc_state_lock);
 
 	mutex_init(&priv->bfregs.reg_head.lock);
 	mutex_init(&priv->bfregs.wc_head.lock);
@@ -1916,6 +1917,7 @@ void mlx5_mdev_uninit(struct mlx5_core_dev *dev)
 	mutex_destroy(&priv->alloc_mutex);
 	mutex_destroy(&priv->bfregs.wc_head.lock);
 	mutex_destroy(&priv->bfregs.reg_head.lock);
+	mutex_destroy(&dev->wc_state_lock);
 	mutex_destroy(&dev->mlx5e_res.uplink_netdev_lock);
 	mutex_destroy(&dev->intf_state_mutex);
 	lockdep_unregister_key(&dev->lock_key);

include/linux/mlx5/driver.h

@@ -766,6 +766,12 @@ struct mlx5_hca_cap {
 	u32 max[MLX5_UN_SZ_DW(hca_cap_union)];
 };
 
+enum mlx5_wc_state {
+	MLX5_WC_STATE_UNINITIALIZED,
+	MLX5_WC_STATE_UNSUPPORTED,
+	MLX5_WC_STATE_SUPPORTED,
+};
+
 struct mlx5_core_dev {
 	struct device *device;
 	enum mlx5_coredev_type coredev_type;
@@ -824,6 +830,9 @@ struct mlx5_core_dev {
 #endif
 	u64 num_ipsec_offloads;
 	struct mlx5_sd          *sd;
+	enum mlx5_wc_state wc_state;
+	/* sync write combining state */
+	struct mutex wc_state_lock;
 };
 
 struct mlx5_db {
@@ -1375,4 +1384,6 @@ static inline bool mlx5_is_macsec_roce_supported(struct mlx5_core_dev *mdev)
 enum {
 	MLX5_OCTWORD = 16,
 };
+
+bool mlx5_wc_support_get(struct mlx5_core_dev *mdev);
 #endif /* MLX5_DRIVER_H */