Re: [dpdk-dev] [PATCH 1/7] bus/vdev: add DMA mapping ops

["Xia, Chenbo" <chenbo.xia@intel.com>]

Hi Maxime,

> -----Original Message-----
> From: dev <dev-bounces@dpdk.org> On Behalf Of Maxime Coquelin
> Sent: Friday, September 11, 2020 11:08 PM
> To: dev@dpdk.org; Fu, Patrick <patrick.fu@intel.com>; amorenoz@redhat.com
> Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
> Subject: [dpdk-dev] [PATCH 1/7] bus/vdev: add DMA mapping ops
> 
> Add DMA map/unmap operation callbacks to the vdev bus, which
> could be used by DMA capable vdev drivers.
> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  drivers/bus/vdev/rte_bus_vdev.h | 46 +++++++++++++++++++++++++++--
>  drivers/bus/vdev/vdev.c         | 52 +++++++++++++++++++++++++++++++++
>  2 files changed, 95 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/bus/vdev/rte_bus_vdev.h
> b/drivers/bus/vdev/rte_bus_vdev.h
> index 78a032cea8..3fe0b35a82 100644
> --- a/drivers/bus/vdev/rte_bus_vdev.h
> +++ b/drivers/bus/vdev/rte_bus_vdev.h
> @@ -63,14 +63,54 @@ typedef int (rte_vdev_probe_t)(struct rte_vdev_device
> *dev);
>   */
>  typedef int (rte_vdev_remove_t)(struct rte_vdev_device *dev);
> 
> +/**
> + * Driver-specific DMA mapping. After a successful call the device
> + * will be able to read/write from/to this segment.
> + *
> + * @param dev
> + *   Pointer to the Virtual device.
> + * @param addr
> + *   Starting virtual address of memory to be mapped.
> + * @param iova
> + *   Starting IOVA address of memory to be mapped.
> + * @param len
> + *   Length of memory segment being mapped.
> + * @return
> + *   - 0 On success.
> + *   - Negative value and rte_errno is set otherwise.
> + */
> +typedef int (rte_vdev_dma_map_t)(struct rte_vdev_device *dev, void *addr,
> +			    uint64_t iova, size_t len);
> +
> +/**
> + * Driver-specific DMA un-mapping. After a successful call the device
> + * will not be able to read/write from/to this segment.
> + *
> + * @param dev
> + *   Pointer to the Virtual device.
> + * @param addr
> + *   Starting virtual address of memory to be unmapped.
> + * @param iova
> + *   Starting IOVA address of memory to be unmapped.
> + * @param len
> + *   Length of memory segment being unmapped.
> + * @return
> + *   - 0 On success.
> + *   - Negative value and rte_errno is set otherwise.
> + */
> +typedef int (rte_vdev_dma_unmap_t)(struct rte_vdev_device *dev, void
> *addr,
> +			      uint64_t iova, size_t len);
> +
>  /**
>   * A virtual device driver abstraction.
>   */
>  struct rte_vdev_driver {
>  	TAILQ_ENTRY(rte_vdev_driver) next; /**< Next in list. */
> -	struct rte_driver driver;      /**< Inherited general driver. */
> -	rte_vdev_probe_t *probe;       /**< Virtual device probe function.
> */
> -	rte_vdev_remove_t *remove;     /**< Virtual device remove function.
> */
> +	struct rte_driver driver;        /**< Inherited general driver. */
> +	rte_vdev_probe_t *probe;         /**< Virtual device probe function.
> */
> +	rte_vdev_remove_t *remove;       /**< Virtual device remove function.
> */
> +	rte_vdev_dma_map_t *dma_map;     /**< vdev DMA map function. */
> +	rte_vdev_dma_unmap_t *dma_unmap; /**< vdev DMA unmap function. */
>  };

I think we'd better unify the term 'Virtual device' or 'vdev'? Maybe just
use Virtual device.

> 
>  /**
> diff --git a/drivers/bus/vdev/vdev.c b/drivers/bus/vdev/vdev.c
> index d746149a2e..455d0bd0c2 100644
> --- a/drivers/bus/vdev/vdev.c
> +++ b/drivers/bus/vdev/vdev.c
> @@ -134,6 +134,56 @@ vdev_parse(const char *name, void *addr)
>  	return driver == NULL;
>  }
> 
> +static int
> +vdev_dma_map(struct rte_device *dev, void *addr, uint64_t iova, size_t
> len)
> +{
> +	struct rte_vdev_device *vdev = RTE_DEV_TO_VDEV(dev);
> +	const struct rte_vdev_driver *driver;
> +
> +	if (!vdev) {
> +		rte_errno = EINVAL;
> +		return -1;
> +	}
> +
> +	if (!vdev->device.driver) {
> +		VDEV_LOG(DEBUG, "no driver attach to device %s", dev->name);
> +		return 1;
> +	}
> +
> +	driver = container_of(vdev->device.driver, const struct
> rte_vdev_driver,
> +			driver);
> +
> +	if (driver->dma_map)
> +		return driver->dma_map(vdev, addr, iova, len);
> +
> +	return 0;
> +}
> +
> +static int
> +vdev_dma_unmap(struct rte_device *dev, void *addr, uint64_t iova, size_t
> len)
> +{
> +	struct rte_vdev_device *vdev = RTE_DEV_TO_VDEV(dev);
> +	const struct rte_vdev_driver *driver;
> +
> +	if (!vdev) {
> +		rte_errno = EINVAL;
> +		return -1;
> +	}
> +
> +	if (!vdev->device.driver) {
> +		VDEV_LOG(DEBUG, "no driver attach to device %s", dev->name);
> +		return 1;
> +	}
> +
> +	driver = container_of(vdev->device.driver, const struct
> rte_vdev_driver,
> +			driver);
> +
> +	if (driver->dma_unmap)
> +		return driver->dma_unmap(vdev, addr, iova, len);
> +
> +	return 0;	return 0;

Duplicate return here 😊

Thanks!
Chenbo

> +}
> +
>  static int
>  vdev_probe_all_drivers(struct rte_vdev_device *dev)
>  {
> @@ -551,6 +601,8 @@ static struct rte_bus rte_vdev_bus = {
>  	.plug = vdev_plug,
>  	.unplug = vdev_unplug,
>  	.parse = vdev_parse,
> +	.dma_map = vdev_dma_map,
> +	.dma_unmap = vdev_dma_unmap,
>  	.dev_iterate = rte_vdev_dev_iterate,
>  };
> 
> --
> 2.26.2