Re: [dpdk-dev] [PATCH v2 05/13] vdpa/mlx5: prepare HW queues

[Maxime Coquelin <maxime.coquelin@redhat.com>]

On 1/29/20 11:09 AM, Matan Azrad wrote:
> As an arrangement to the vitrio queues creation, a 2 QPs and CQ may be
> created for the virtio queue.
> 
> The design is to trigger an event for the guest and for the vdpa driver
> when a new CQE is posted by the HW after the packet transition.
> 
> This patch add the basic operations to create and destroy the above HW
> objects  and to trigger the CQE events when a new CQE is posted.
> 
> Signed-off-by: Matan Azrad <matan@mellanox.com>
> Acked-by: Viacheslav Ovsiienko <viacheslavo@mellanox.com>
> ---
>  drivers/common/mlx5/mlx5_prm.h      |   4 +
>  drivers/vdpa/mlx5/Makefile          |   1 +
>  drivers/vdpa/mlx5/meson.build       |   1 +
>  drivers/vdpa/mlx5/mlx5_vdpa.h       |  89 ++++++++
>  drivers/vdpa/mlx5/mlx5_vdpa_event.c | 399 ++++++++++++++++++++++++++++++++++++
>  5 files changed, 494 insertions(+)
>  create mode 100644 drivers/vdpa/mlx5/mlx5_vdpa_event.c
> 
> diff --git a/drivers/common/mlx5/mlx5_prm.h b/drivers/common/mlx5/mlx5_prm.h
> index b48cd0a..b533798 100644
> --- a/drivers/common/mlx5/mlx5_prm.h
> +++ b/drivers/common/mlx5/mlx5_prm.h
> @@ -392,6 +392,10 @@ struct mlx5_cqe {
>  /* CQE format value. */
>  #define MLX5_COMPRESSED 0x3
>  
> +/* CQ doorbell cmd types. */
> +#define MLX5_CQ_DBR_CMD_SOL_ONLY (1 << 24)
> +#define MLX5_CQ_DBR_CMD_ALL (0 << 24)
> +
>  /* Action type of header modification. */
>  enum {
>  	MLX5_MODIFICATION_TYPE_SET = 0x1,
> diff --git a/drivers/vdpa/mlx5/Makefile b/drivers/vdpa/mlx5/Makefile
> index 5472797..7f13756 100644
> --- a/drivers/vdpa/mlx5/Makefile
> +++ b/drivers/vdpa/mlx5/Makefile
> @@ -9,6 +9,7 @@ LIB = librte_pmd_mlx5_vdpa.a
>  # Sources.
>  SRCS-$(CONFIG_RTE_LIBRTE_MLX5_VDPA_PMD) += mlx5_vdpa.c
>  SRCS-$(CONFIG_RTE_LIBRTE_MLX5_VDPA_PMD) += mlx5_vdpa_mem.c
> +SRCS-$(CONFIG_RTE_LIBRTE_MLX5_VDPA_PMD) += mlx5_vdpa_event.c
>  
>  # Basic CFLAGS.
>  CFLAGS += -O3
> diff --git a/drivers/vdpa/mlx5/meson.build b/drivers/vdpa/mlx5/meson.build
> index 7e5dd95..c609f7c 100644
> --- a/drivers/vdpa/mlx5/meson.build
> +++ b/drivers/vdpa/mlx5/meson.build
> @@ -13,6 +13,7 @@ deps += ['hash', 'common_mlx5', 'vhost', 'bus_pci', 'eal', 'sched']
>  sources = files(
>  	'mlx5_vdpa.c',
>  	'mlx5_vdpa_mem.c',
> +	'mlx5_vdpa_event.c',
>  )
>  cflags_options = [
>  	'-std=c11',
> diff --git a/drivers/vdpa/mlx5/mlx5_vdpa.h b/drivers/vdpa/mlx5/mlx5_vdpa.h
> index e27baea..30030b7 100644
> --- a/drivers/vdpa/mlx5/mlx5_vdpa.h
> +++ b/drivers/vdpa/mlx5/mlx5_vdpa.h
> @@ -9,9 +9,40 @@
>  
>  #include <rte_vdpa.h>
>  #include <rte_vhost.h>
> +#include <rte_spinlock.h>
> +#include <rte_interrupts.h>
>  
>  #include <mlx5_glue.h>
>  #include <mlx5_devx_cmds.h>
> +#include <mlx5_prm.h>
> +
> +
> +#define MLX5_VDPA_INTR_RETRIES 256
> +#define MLX5_VDPA_INTR_RETRIES_USEC 1000
> +
> +struct mlx5_vdpa_cq {
> +	uint16_t log_desc_n;
> +	uint32_t cq_ci:24;
> +	uint32_t arm_sn:2;
> +	rte_spinlock_t sl;
> +	struct mlx5_devx_obj *cq;
> +	struct mlx5dv_devx_umem *umem_obj;
> +	union {
> +		volatile void *umem_buf;
> +		volatile struct mlx5_cqe *cqes;
> +	};
> +	volatile uint32_t *db_rec;
> +	uint64_t errors;
> +};
> +
> +struct mlx5_vdpa_event_qp {
> +	struct mlx5_vdpa_cq cq;
> +	struct mlx5_devx_obj *fw_qp;
> +	struct mlx5_devx_obj *sw_qp;
> +	struct mlx5dv_devx_umem *umem_obj;
> +	void *umem_buf;
> +	volatile uint32_t *db_rec;
> +};
>  
>  struct mlx5_vdpa_query_mr {
>  	SLIST_ENTRY(mlx5_vdpa_query_mr) next;
> @@ -34,6 +65,10 @@ struct mlx5_vdpa_priv {
>  	uint32_t gpa_mkey_index;
>  	struct ibv_mr *null_mr;
>  	struct rte_vhost_memory *vmem;
> +	uint32_t eqn;
> +	struct mlx5dv_devx_event_channel *eventc;
> +	struct mlx5dv_devx_uar *uar;
> +	struct rte_intr_handle intr_handle;
>  	SLIST_HEAD(mr_list, mlx5_vdpa_query_mr) mr_list;
>  };
>  
> @@ -57,4 +92,58 @@ struct mlx5_vdpa_priv {
>   */
>  int mlx5_vdpa_mem_register(struct mlx5_vdpa_priv *priv);
>  
> +
> +/**
> + * Create an event QP and all its related resources.
> + *
> + * @param[in] priv
> + *   The vdpa driver private structure.
> + * @param[in] desc_n
> + *   Number of descriptors.
> + * @param[in] callfd
> + *   The guest notification file descriptor.
> + * @param[in/out] eqp
> + *   Pointer to the event QP structure.
> + *
> + * @return
> + *   0 on success, -1 otherwise and rte_errno is set.
> + */
> +int mlx5_vdpa_event_qp_create(struct mlx5_vdpa_priv *priv, uint16_t desc_n,
> +			      int callfd, struct mlx5_vdpa_event_qp *eqp);
> +
> +/**
> + * Destroy an event QP and all its related resources.
> + *
> + * @param[in/out] eqp
> + *   Pointer to the event QP structure.
> + */
> +void mlx5_vdpa_event_qp_destroy(struct mlx5_vdpa_event_qp *eqp);
> +
> +/**
> + * Release all the event global resources.
> + *
> + * @param[in] priv
> + *   The vdpa driver private structure.
> + */
> +void mlx5_vdpa_event_qp_global_release(struct mlx5_vdpa_priv *priv);
> +
> +/**
> + * Setup CQE event.
> + *
> + * @param[in] priv
> + *   The vdpa driver private structure.
> + *
> + * @return
> + *   0 on success, a negative errno value otherwise and rte_errno is set.
> + */
> +int mlx5_vdpa_cqe_event_setup(struct mlx5_vdpa_priv *priv);
> +
> +/**
> + * Unset CQE event .
> + *
> + * @param[in] priv
> + *   The vdpa driver private structure.
> + */
> +void mlx5_vdpa_cqe_event_unset(struct mlx5_vdpa_priv *priv);
> +
>  #endif /* RTE_PMD_MLX5_VDPA_H_ */
> diff --git a/drivers/vdpa/mlx5/mlx5_vdpa_event.c b/drivers/vdpa/mlx5/mlx5_vdpa_event.c
> new file mode 100644
> index 0000000..35518ad
> --- /dev/null
> +++ b/drivers/vdpa/mlx5/mlx5_vdpa_event.c
> @@ -0,0 +1,399 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright 2019 Mellanox Technologies, Ltd
> + */
> +#include <unistd.h>
> +#include <stdint.h>
> +#include <fcntl.h>
> +
> +#include <rte_malloc.h>
> +#include <rte_errno.h>
> +#include <rte_lcore.h>
> +#include <rte_atomic.h>
> +#include <rte_common.h>
> +#include <rte_io.h>
> +
> +#include <mlx5_common.h>
> +
> +#include "mlx5_vdpa_utils.h"
> +#include "mlx5_vdpa.h"
> +
> +
> +void
> +mlx5_vdpa_event_qp_global_release(struct mlx5_vdpa_priv *priv)
> +{
> +	if (priv->uar) {
> +		mlx5_glue->devx_free_uar(priv->uar);
> +		priv->uar = NULL;
> +	}
> +	if (priv->eventc) {
> +		mlx5_glue->devx_destroy_event_channel(priv->eventc);
> +		priv->eventc = NULL;
> +	}
> +	priv->eqn = 0;
> +}
> +
> +/* Prepare all the global resources for all the event objects.*/
> +static int
> +mlx5_vdpa_event_qp_global_prepare(struct mlx5_vdpa_priv *priv)
> +{
> +	uint32_t lcore;
> +
> +	if (priv->eventc)
> +		return 0;
> +	lcore = (uint32_t)rte_lcore_to_cpu_id(-1);
> +	if (mlx5_glue->devx_query_eqn(priv->ctx, lcore, &priv->eqn)) {
> +		rte_errno = errno;
> +		DRV_LOG(ERR, "Failed to query EQ number %d.", rte_errno);
> +		return -1;
> +	}
> +	priv->eventc = mlx5_glue->devx_create_event_channel(priv->ctx,
> +			   MLX5DV_DEVX_CREATE_EVENT_CHANNEL_FLAGS_OMIT_EV_DATA);
> +	if (!priv->eventc) {
> +		rte_errno = errno;
> +		DRV_LOG(ERR, "Failed to create event channel %d.",
> +			rte_errno);
> +		goto error;
> +	}
> +	priv->uar = mlx5_glue->devx_alloc_uar(priv->ctx, 0);
> +	if (!priv->uar) {
> +		rte_errno = errno;
> +		DRV_LOG(ERR, "Failed to allocate UAR.");
> +		goto error;
> +	}
> +	return 0;
> +error:
> +	mlx5_vdpa_event_qp_global_release(priv);
> +	return -1;
> +}
> +
> +static void
> +mlx5_vdpa_cq_destroy(struct mlx5_vdpa_cq *cq)
> +{
> +	if (cq->cq)
> +		claim_zero(mlx5_devx_cmd_destroy(cq->cq));
> +	if (cq->umem_obj)
> +		claim_zero(mlx5_glue->devx_umem_dereg(cq->umem_obj));
> +	if (cq->umem_buf)
> +		rte_free((void *)(uintptr_t)cq->umem_buf);
> +	memset(cq, 0, sizeof(*cq));
> +}
> +
> +static inline void
> +mlx5_vdpa_cq_arm(struct mlx5_vdpa_priv *priv, struct mlx5_vdpa_cq *cq)
> +{
> +	const unsigned int cqe_mask = (1 << cq->log_desc_n) - 1;
> +	uint32_t arm_sn = cq->arm_sn << MLX5_CQ_SQN_OFFSET;
> +	uint32_t cq_ci = cq->cq_ci & MLX5_CI_MASK & cqe_mask;
> +	uint32_t doorbell_hi = arm_sn | MLX5_CQ_DBR_CMD_ALL | cq_ci;
> +	uint64_t doorbell = ((uint64_t)doorbell_hi << 32) | cq->cq->id;
> +	uint64_t db_be = rte_cpu_to_be_64(doorbell);
> +	uint32_t *addr = RTE_PTR_ADD(priv->uar->base_addr, MLX5_CQ_DOORBELL);
> +
> +	rte_io_wmb();
> +	cq->db_rec[MLX5_CQ_ARM_DB] = rte_cpu_to_be_32(doorbell_hi);
> +	rte_wmb();
> +#ifdef RTE_ARCH_64
> +	*(uint64_t *)addr = db_be;
> +#else
> +	*(uint32_t *)addr = db_be;
> +	rte_io_wmb();
> +	*((uint32_t *)addr + 1) = db_be >> 32;
> +#endif
> +	cq->arm_sn++;
> +}
> +
> +static int
> +mlx5_vdpa_cq_create(struct mlx5_vdpa_priv *priv, uint16_t log_desc_n,
> +		    int callfd, struct mlx5_vdpa_cq *cq)
> +{
> +	struct mlx5_devx_cq_attr attr;
> +	size_t pgsize = sysconf(_SC_PAGESIZE);
> +	uint32_t umem_size;
> +	int ret;
> +	uint16_t event_nums[1] = {0};
> +
> +	cq->log_desc_n = log_desc_n;
> +	umem_size = sizeof(struct mlx5_cqe) * (1 << log_desc_n) +
> +							sizeof(*cq->db_rec) * 2;
> +	cq->umem_buf = rte_zmalloc(__func__, umem_size, 4096);
> +	if (!cq->umem_buf) {
> +		DRV_LOG(ERR, "Failed to allocate memory for CQ.");
> +		rte_errno = ENOMEM;
> +		return -ENOMEM;
> +	}
> +	cq->umem_obj = mlx5_glue->devx_umem_reg(priv->ctx,
> +						(void *)(uintptr_t)cq->umem_buf,
> +						umem_size,
> +						IBV_ACCESS_LOCAL_WRITE);
> +	if (!cq->umem_obj) {
> +		DRV_LOG(ERR, "Failed to register umem for CQ.");
> +		goto error;
> +	}
> +	attr.q_umem_valid = 1;
> +	attr.db_umem_valid = 1;
> +	attr.use_first_only = 0;
> +	attr.overrun_ignore = 0;
> +	attr.uar_page_id = priv->uar->page_id;
> +	attr.q_umem_id = cq->umem_obj->umem_id;
> +	attr.q_umem_offset = 0;
> +	attr.db_umem_id = cq->umem_obj->umem_id;
> +	attr.db_umem_offset = sizeof(struct mlx5_cqe) * (1 << log_desc_n);
> +	attr.eqn = priv->eqn;
> +	attr.log_cq_size = log_desc_n;
> +	attr.log_page_size = rte_log2_u32(pgsize);
> +	cq->cq = mlx5_devx_cmd_create_cq(priv->ctx, &attr);
> +	if (!cq->cq)
> +		goto error;
> +	cq->db_rec = RTE_PTR_ADD(cq->umem_buf, (uintptr_t)attr.db_umem_offset);
> +	cq->cq_ci = 0;
> +	rte_spinlock_init(&cq->sl);
> +	/* Subscribe CQ event to the event channel controlled by the driver. */
> +	ret = mlx5_glue->devx_subscribe_devx_event(priv->eventc, cq->cq->obj,
> +						   sizeof(event_nums),
> +						   event_nums,
> +						   (uint64_t)(uintptr_t)cq);
> +	if (ret) {
> +		DRV_LOG(ERR, "Failed to subscribe CQE event.");
> +		rte_errno = errno;
> +		goto error;
> +	}
> +	/* Subscribe CQ event to the guest FD only if it is not in poll mode. */
> +	if (callfd != -1) {
> +		ret = mlx5_glue->devx_subscribe_devx_event_fd(priv->eventc,
> +							      callfd,
> +							      cq->cq->obj, 0);
> +		if (ret) {
> +			DRV_LOG(ERR, "Failed to subscribe CQE event fd.");
> +			rte_errno = errno;
> +			goto error;
> +		}
> +	}
> +	/* First arming. */
> +	mlx5_vdpa_cq_arm(priv, cq);
> +	return 0;
> +error:
> +	mlx5_vdpa_cq_destroy(cq);
> +	return -1;
> +}
> +
> +static inline void __rte_unused
> +mlx5_vdpa_cq_poll(struct mlx5_vdpa_priv *priv __rte_unused,
> +		  struct mlx5_vdpa_cq *cq)
> +{
> +	struct mlx5_vdpa_event_qp *eqp =
> +				container_of(cq, struct mlx5_vdpa_event_qp, cq);
> +	const unsigned int cqe_size = 1 << cq->log_desc_n;
> +	const unsigned int cqe_mask = cqe_size - 1;
> +	int ret;
> +
> +	do {
> +		volatile struct mlx5_cqe *cqe = cq->cqes + (cq->cq_ci &
> +							    cqe_mask);
> +
> +		ret = check_cqe(cqe, cqe_size, cq->cq_ci);
> +		switch (ret) {
> +		case MLX5_CQE_STATUS_ERR:
> +			cq->errors++;
> +			/*fall-through*/
> +		case MLX5_CQE_STATUS_SW_OWN:
> +			cq->cq_ci++;
> +			break;
> +		case MLX5_CQE_STATUS_HW_OWN:
> +		default:
> +			break;
> +		}
> +	} while (ret != MLX5_CQE_STATUS_HW_OWN);

Isn't there a risk of endless loop here?

> +	rte_io_wmb();
> +	/* Ring CQ doorbell record. */
> +	cq->db_rec[0] = rte_cpu_to_be_32(cq->cq_ci);
> +	rte_io_wmb();
> +	/* Ring SW QP doorbell record. */
> +	eqp->db_rec[0] = rte_cpu_to_be_32(cq->cq_ci + cqe_size);
> +}
> +