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

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

On 1/31/20 7:56 AM, Matan Azrad wrote:
> 
> Hi
> 
> From: Maxime Coquelin
>> 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?
> 
> No. maximum iterations number is the CQ size , since HW cannot write more CQEs before the doorbell record is updated.

Ok.