Re: [PATCH v1 1/1] vhost: integrate dmadev in asynchronous datapath

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

Hi Jiayu,

On 12/30/21 22:55, Jiayu Hu wrote:
> Since dmadev is introduced in 21.11, to avoid the overhead of vhost DMA
> abstraction layer and simplify application logics, this patch integrates
> dmadev in asynchronous data path.
> 
> Signed-off-by: Jiayu Hu <jiayu.hu@intel.com>
> Signed-off-by: Sunil Pai G <sunil.pai.g@intel.com>
> ---
>   doc/guides/prog_guide/vhost_lib.rst |  70 ++++-----
>   examples/vhost/Makefile             |   2 +-
>   examples/vhost/ioat.c               | 218 --------------------------
>   examples/vhost/ioat.h               |  63 --------
>   examples/vhost/main.c               | 230 +++++++++++++++++++++++-----
>   examples/vhost/main.h               |  11 ++
>   examples/vhost/meson.build          |   6 +-
>   lib/vhost/meson.build               |   3 +-
>   lib/vhost/rte_vhost_async.h         | 121 +++++----------
>   lib/vhost/version.map               |   3 +
>   lib/vhost/vhost.c                   | 130 +++++++++++-----
>   lib/vhost/vhost.h                   |  53 ++++++-
>   lib/vhost/virtio_net.c              | 206 +++++++++++++++++++------
>   13 files changed, 587 insertions(+), 529 deletions(-)
>   delete mode 100644 examples/vhost/ioat.c
>   delete mode 100644 examples/vhost/ioat.h



> diff --git a/doc/guides/prog_guide/vhost_lib.rst b/doc/guides/prog_guide/vhost_lib.rst
> index 76f5d303c9..bdce7cbf02 100644
> --- a/doc/guides/prog_guide/vhost_lib.rst
> +++ b/doc/guides/prog_guide/vhost_lib.rst
> @@ -218,38 +218,12 @@ The following is an overview of some key Vhost API functions:
>   
>     Enable or disable zero copy feature of the vhost crypto backend.
>   
> -* ``rte_vhost_async_channel_register(vid, queue_id, config, ops)``
> +* ``rte_vhost_async_channel_register(vid, queue_id)``
>   
>     Register an async copy device channel for a vhost queue after vring
> -  is enabled. Following device ``config`` must be specified together
> -  with the registration:
> +  is enabled.
>   
> -  * ``features``
> -
> -    This field is used to specify async copy device features.
> -
> -    ``RTE_VHOST_ASYNC_INORDER`` represents the async copy device can
> -    guarantee the order of copy completion is the same as the order
> -    of copy submission.
> -
> -    Currently, only ``RTE_VHOST_ASYNC_INORDER`` capable device is
> -    supported by vhost.
> -
> -  Applications must provide following ``ops`` callbacks for vhost lib to
> -  work with the async copy devices:
> -
> -  * ``transfer_data(vid, queue_id, descs, opaque_data, count)``
> -
> -    vhost invokes this function to submit copy data to the async devices.
> -    For non-async_inorder capable devices, ``opaque_data`` could be used
> -    for identifying the completed packets.
> -
> -  * ``check_completed_copies(vid, queue_id, opaque_data, max_packets)``
> -
> -    vhost invokes this function to get the copy data completed by async
> -    devices.
> -
> -* ``rte_vhost_async_channel_register_thread_unsafe(vid, queue_id, config, ops)``
> +* ``rte_vhost_async_channel_register_thread_unsafe(vid, queue_id)``
>   
>     Register an async copy device channel for a vhost queue without
>     performing any locking.
> @@ -277,18 +251,13 @@ The following is an overview of some key Vhost API functions:
>     This function is only safe to call in vhost callback functions
>     (i.e., struct rte_vhost_device_ops).
>   
> -* ``rte_vhost_submit_enqueue_burst(vid, queue_id, pkts, count, comp_pkts, comp_count)``
> +* ``rte_vhost_submit_enqueue_burst(vid, queue_id, pkts, count, dma_id, dma_vchan)``
>   
>     Submit an enqueue request to transmit ``count`` packets from host to guest
> -  by async data path. Successfully enqueued packets can be transfer completed
> -  or being occupied by DMA engines; transfer completed packets are returned in
> -  ``comp_pkts``, but others are not guaranteed to finish, when this API
> -  call returns.
> +  by async data path. Applications must not free the packets submitted for
> +  enqueue until the packets are completed.
>   
> -  Applications must not free the packets submitted for enqueue until the
> -  packets are completed.
> -
> -* ``rte_vhost_poll_enqueue_completed(vid, queue_id, pkts, count)``
> +* ``rte_vhost_poll_enqueue_completed(vid, queue_id, pkts, count, dma_id, dma_vchan)``
>   
>     Poll enqueue completion status from async data path. Completed packets
>     are returned to applications through ``pkts``.
> @@ -298,7 +267,7 @@ The following is an overview of some key Vhost API functions:
>     This function returns the amount of in-flight packets for the vhost
>     queue using async acceleration.
>   
> -* ``rte_vhost_clear_queue_thread_unsafe(vid, queue_id, **pkts, count)``
> +* ``rte_vhost_clear_queue_thread_unsafe(vid, queue_id, **pkts, count, dma_id, dma_vchan)``
>   
>     Clear inflight packets which are submitted to DMA engine in vhost async data
>     path. Completed packets are returned to applications through ``pkts``.
> @@ -442,3 +411,26 @@ Finally, a set of device ops is defined for device specific operations:
>   * ``get_notify_area``
>   
>     Called to get the notify area info of the queue.
> +
> +Vhost asynchronous data path
> +----------------------------
> +
> +Vhost asynchronous data path leverages DMA devices to offload memory
> +copies from the CPU and it is implemented in an asynchronous way. It
> +enables applcations, like OVS, to save CPU cycles and hide memory copy

s/applcations/applications/

> +overhead, thus achieving higher throughput.
> +
> +Vhost doesn't manage DMA devices and applications, like OVS, need to
> +manage and configure DMA devices. Applications need to tell vhost what
> +DMA devices to use in every data path function call. This design enables
> +the flexibility for applications to dynamically use DMA channels in
> +different function modules, not limited in vhost.
> +
> +In addition, vhost supports M:N mapping between vrings and DMA virtual
> +channels. Specifically, one vring can use multiple different DMA channels
> +and one DMA channel can be shared by multiple vrings at the same time.
> +The reason of enabling one vring to use multiple DMA channels is that
> +it's possible that more than one dataplane threads enqueue packets to
> +the same vring with their own DMA virtual channels. Besides, the number
> +of DMA devices is limited. For the purpose of scaling, it's necessary to
> +support sharing DMA channels among vrings.
> diff --git a/examples/vhost/Makefile b/examples/vhost/Makefile
> index 587ea2ab47..975a5dfe40 100644
> --- a/examples/vhost/Makefile
> +++ b/examples/vhost/Makefile
> @@ -5,7 +5,7 @@
>   APP = vhost-switch
>   
>   # all source are stored in SRCS-y
> -SRCS-y := main.c virtio_net.c ioat.c
> +SRCS-y := main.c virtio_net.c
>   
>   PKGCONF ?= pkg-config
>   
> diff --git a/examples/vhost/ioat.c b/examples/vhost/ioat.c
> deleted file mode 100644
> index 9aeeb12fd9..0000000000
> --- a/examples/vhost/ioat.c
> +++ /dev/null
> @@ -1,218 +0,0 @@
> -/* SPDX-License-Identifier: BSD-3-Clause
> - * Copyright(c) 2010-2020 Intel Corporation
> - */
> -
> -#include <sys/uio.h>
> -#ifdef RTE_RAW_IOAT
> -#include <rte_rawdev.h>
> -#include <rte_ioat_rawdev.h>
> -
> -#include "ioat.h"
> -#include "main.h"
> -
> -struct dma_for_vhost dma_bind[MAX_VHOST_DEVICE];
> -
> -struct packet_tracker {
> -	unsigned short size_track[MAX_ENQUEUED_SIZE];
> -	unsigned short next_read;
> -	unsigned short next_write;
> -	unsigned short last_remain;
> -	unsigned short ioat_space;
> -};
> -
> -struct packet_tracker cb_tracker[MAX_VHOST_DEVICE];
> -
> -int
> -open_ioat(const char *value)
> -{
> -	struct dma_for_vhost *dma_info = dma_bind;
> -	char *input = strndup(value, strlen(value) + 1);
> -	char *addrs = input;
> -	char *ptrs[2];
> -	char *start, *end, *substr;
> -	int64_t vid, vring_id;
> -	struct rte_ioat_rawdev_config config;
> -	struct rte_rawdev_info info = { .dev_private = &config };
> -	char name[32];
> -	int dev_id;
> -	int ret = 0;
> -	uint16_t i = 0;
> -	char *dma_arg[MAX_VHOST_DEVICE];
> -	int args_nr;
> -
> -	while (isblank(*addrs))
> -		addrs++;
> -	if (*addrs == '\0') {
> -		ret = -1;
> -		goto out;
> -	}
> -
> -	/* process DMA devices within bracket. */
> -	addrs++;
> -	substr = strtok(addrs, ";]");
> -	if (!substr) {
> -		ret = -1;
> -		goto out;
> -	}
> -	args_nr = rte_strsplit(substr, strlen(substr),
> -			dma_arg, MAX_VHOST_DEVICE, ',');
> -	if (args_nr <= 0) {
> -		ret = -1;
> -		goto out;
> -	}
> -	while (i < args_nr) {
> -		char *arg_temp = dma_arg[i];
> -		uint8_t sub_nr;
> -		sub_nr = rte_strsplit(arg_temp, strlen(arg_temp), ptrs, 2, '@');
> -		if (sub_nr != 2) {
> -			ret = -1;
> -			goto out;
> -		}
> -
> -		start = strstr(ptrs[0], "txd");
> -		if (start == NULL) {
> -			ret = -1;
> -			goto out;
> -		}
> -
> -		start += 3;
> -		vid = strtol(start, &end, 0);
> -		if (end == start) {
> -			ret = -1;
> -			goto out;
> -		}
> -
> -		vring_id = 0 + VIRTIO_RXQ;
> -		if (rte_pci_addr_parse(ptrs[1],
> -				&(dma_info + vid)->dmas[vring_id].addr) < 0) {
> -			ret = -1;
> -			goto out;
> -		}
> -
> -		rte_pci_device_name(&(dma_info + vid)->dmas[vring_id].addr,
> -				name, sizeof(name));
> -		dev_id = rte_rawdev_get_dev_id(name);
> -		if (dev_id == (uint16_t)(-ENODEV) ||
> -		dev_id == (uint16_t)(-EINVAL)) {
> -			ret = -1;
> -			goto out;
> -		}
> -
> -		if (rte_rawdev_info_get(dev_id, &info, sizeof(config)) < 0 ||
> -		strstr(info.driver_name, "ioat") == NULL) {
> -			ret = -1;
> -			goto out;
> -		}
> -
> -		(dma_info + vid)->dmas[vring_id].dev_id = dev_id;
> -		(dma_info + vid)->dmas[vring_id].is_valid = true;
> -		config.ring_size = IOAT_RING_SIZE;
> -		config.hdls_disable = true;
> -		if (rte_rawdev_configure(dev_id, &info, sizeof(config)) < 0) {
> -			ret = -1;
> -			goto out;
> -		}
> -		rte_rawdev_start(dev_id);
> -		cb_tracker[dev_id].ioat_space = IOAT_RING_SIZE - 1;
> -		dma_info->nr++;
> -		i++;
> -	}
> -out:
> -	free(input);
> -	return ret;
> -}
> -
> -int32_t
> -ioat_transfer_data_cb(int vid, uint16_t queue_id,
> -		struct rte_vhost_iov_iter *iov_iter,
> -		struct rte_vhost_async_status *opaque_data, uint16_t count)
> -{
> -	uint32_t i_iter;
> -	uint16_t dev_id = dma_bind[vid].dmas[queue_id * 2 + VIRTIO_RXQ].dev_id;
> -	struct rte_vhost_iov_iter *iter = NULL;
> -	unsigned long i_seg;
> -	unsigned short mask = MAX_ENQUEUED_SIZE - 1;
> -	unsigned short write = cb_tracker[dev_id].next_write;
> -
> -	if (!opaque_data) {
> -		for (i_iter = 0; i_iter < count; i_iter++) {
> -			iter = iov_iter + i_iter;
> -			i_seg = 0;
> -			if (cb_tracker[dev_id].ioat_space < iter->nr_segs)
> -				break;
> -			while (i_seg < iter->nr_segs) {
> -				rte_ioat_enqueue_copy(dev_id,
> -					(uintptr_t)(iter->iov[i_seg].src_addr),
> -					(uintptr_t)(iter->iov[i_seg].dst_addr),
> -					iter->iov[i_seg].len,
> -					0,
> -					0);
> -				i_seg++;
> -			}
> -			write &= mask;
> -			cb_tracker[dev_id].size_track[write] = iter->nr_segs;
> -			cb_tracker[dev_id].ioat_space -= iter->nr_segs;
> -			write++;
> -		}
> -	} else {
> -		/* Opaque data is not supported */
> -		return -1;
> -	}
> -	/* ring the doorbell */
> -	rte_ioat_perform_ops(dev_id);
> -	cb_tracker[dev_id].next_write = write;
> -	return i_iter;
> -}
> -
> -int32_t
> -ioat_check_completed_copies_cb(int vid, uint16_t queue_id,
> -		struct rte_vhost_async_status *opaque_data,
> -		uint16_t max_packets)
> -{
> -	if (!opaque_data) {
> -		uintptr_t dump[255];
> -		int n_seg;
> -		unsigned short read, write;
> -		unsigned short nb_packet = 0;
> -		unsigned short mask = MAX_ENQUEUED_SIZE - 1;
> -		unsigned short i;
> -
> -		uint16_t dev_id = dma_bind[vid].dmas[queue_id * 2
> -				+ VIRTIO_RXQ].dev_id;
> -		n_seg = rte_ioat_completed_ops(dev_id, 255, NULL, NULL, dump, dump);
> -		if (n_seg < 0) {
> -			RTE_LOG(ERR,
> -				VHOST_DATA,
> -				"fail to poll completed buf on IOAT device %u",
> -				dev_id);
> -			return 0;
> -		}
> -		if (n_seg == 0)
> -			return 0;
> -
> -		cb_tracker[dev_id].ioat_space += n_seg;
> -		n_seg += cb_tracker[dev_id].last_remain;
> -
> -		read = cb_tracker[dev_id].next_read;
> -		write = cb_tracker[dev_id].next_write;
> -		for (i = 0; i < max_packets; i++) {
> -			read &= mask;
> -			if (read == write)
> -				break;
> -			if (n_seg >= cb_tracker[dev_id].size_track[read]) {
> -				n_seg -= cb_tracker[dev_id].size_track[read];
> -				read++;
> -				nb_packet++;
> -			} else {
> -				break;
> -			}
> -		}
> -		cb_tracker[dev_id].next_read = read;
> -		cb_tracker[dev_id].last_remain = n_seg;
> -		return nb_packet;
> -	}
> -	/* Opaque data is not supported */
> -	return -1;
> -}
> -
> -#endif /* RTE_RAW_IOAT */
> diff --git a/examples/vhost/ioat.h b/examples/vhost/ioat.h
> deleted file mode 100644
> index d9bf717e8d..0000000000
> --- a/examples/vhost/ioat.h
> +++ /dev/null
> @@ -1,63 +0,0 @@
> -/* SPDX-License-Identifier: BSD-3-Clause
> - * Copyright(c) 2010-2020 Intel Corporation
> - */
> -
> -#ifndef _IOAT_H_
> -#define _IOAT_H_
> -
> -#include <rte_vhost.h>
> -#include <rte_pci.h>
> -#include <rte_vhost_async.h>
> -
> -#define MAX_VHOST_DEVICE 1024
> -#define IOAT_RING_SIZE 4096
> -#define MAX_ENQUEUED_SIZE 4096
> -
> -struct dma_info {
> -	struct rte_pci_addr addr;
> -	uint16_t dev_id;
> -	bool is_valid;
> -};
> -
> -struct dma_for_vhost {
> -	struct dma_info dmas[RTE_MAX_QUEUES_PER_PORT * 2];
> -	uint16_t nr;
> -};
> -
> -#ifdef RTE_RAW_IOAT
> -int open_ioat(const char *value);
> -
> -int32_t
> -ioat_transfer_data_cb(int vid, uint16_t queue_id,
> -		struct rte_vhost_iov_iter *iov_iter,
> -		struct rte_vhost_async_status *opaque_data, uint16_t count);
> -
> -int32_t
> -ioat_check_completed_copies_cb(int vid, uint16_t queue_id,
> -		struct rte_vhost_async_status *opaque_data,
> -		uint16_t max_packets);
> -#else
> -static int open_ioat(const char *value __rte_unused)
> -{
> -	return -1;
> -}
> -
> -static int32_t
> -ioat_transfer_data_cb(int vid __rte_unused, uint16_t queue_id __rte_unused,
> -		struct rte_vhost_iov_iter *iov_iter __rte_unused,
> -		struct rte_vhost_async_status *opaque_data __rte_unused,
> -		uint16_t count __rte_unused)
> -{
> -	return -1;
> -}
> -
> -static int32_t
> -ioat_check_completed_copies_cb(int vid __rte_unused,
> -		uint16_t queue_id __rte_unused,
> -		struct rte_vhost_async_status *opaque_data __rte_unused,
> -		uint16_t max_packets __rte_unused)
> -{
> -	return -1;
> -}
> -#endif
> -#endif /* _IOAT_H_ */
> diff --git a/examples/vhost/main.c b/examples/vhost/main.c
> index 33d023aa39..44073499bc 100644
> --- a/examples/vhost/main.c
> +++ b/examples/vhost/main.c
> @@ -24,8 +24,9 @@
>   #include <rte_ip.h>
>   #include <rte_tcp.h>
>   #include <rte_pause.h>
> +#include <rte_dmadev.h>
> +#include <rte_vhost_async.h>
>   
> -#include "ioat.h"
>   #include "main.h"
>   
>   #ifndef MAX_QUEUES
> @@ -56,6 +57,14 @@
>   #define RTE_TEST_TX_DESC_DEFAULT 512
>   
>   #define INVALID_PORT_ID 0xFF
> +#define INVALID_DMA_ID -1
> +
> +#define MAX_VHOST_DEVICE 1024

It is better to define RTE_VHOST_MAX_DEVICES in rte_vhost.h,
and use it here in in vhost library so that it will always be aligned
with the Vhost library.

> +#define DMA_RING_SIZE 4096

As previous review, the DMA ring size should not be hard-coded.
Please use the DMA lib helpers to get the ring size also here.

Looking at the dmadev library, I would just use the max value provided
by the device. What would be the downside of doing so?

Looking at currently available DMA device drivers, this is their
max_desc value:
  - CNXK: 15
  - DPAA: 64
  - HISI: 8192
  - IDXD: 4192
  - IOAT: 4192
  - Skeleton: 8192

So harcoding to 4192 will prevent some to DMA devices to be used, and
will not make full benefit of their capabilities for others.

> +struct dma_for_vhost dma_bind[MAX_VHOST_DEVICE];
> +struct rte_vhost_async_dma_info dma_config[RTE_DMADEV_DEFAULT_MAX];
> +static int dma_count;
>   
>   /* mask of enabled ports */
>   static uint32_t enabled_port_mask = 0;
> @@ -96,8 +105,6 @@ static int builtin_net_driver;
>   
>   static int async_vhost_driver;
>   
> -static char *dma_type;
> -
>   /* Specify timeout (in useconds) between retries on RX. */
>   static uint32_t burst_rx_delay_time = BURST_RX_WAIT_US;
>   /* Specify the number of retries on RX. */
> @@ -196,13 +203,134 @@ struct vhost_bufftable *vhost_txbuff[RTE_MAX_LCORE * MAX_VHOST_DEVICE];
>   #define MBUF_TABLE_DRAIN_TSC	((rte_get_tsc_hz() + US_PER_S - 1) \
>   				 / US_PER_S * BURST_TX_DRAIN_US)
>   
> +static inline bool
> +is_dma_configured(int16_t dev_id)
> +{
> +	int i;
> +
> +	for (i = 0; i < dma_count; i++) {
> +		if (dma_config[i].dev_id == dev_id) {
> +			return true;
> +		}
> +	}

No need for braces for both the loop and the if.

> +	return false;
> +}
> +
>   static inline int
>   open_dma(const char *value)
>   {
> -	if (dma_type != NULL && strncmp(dma_type, "ioat", 4) == 0)
> -		return open_ioat(value);
> +	struct dma_for_vhost *dma_info = dma_bind;
> +	char *input = strndup(value, strlen(value) + 1);
> +	char *addrs = input;
> +	char *ptrs[2];
> +	char *start, *end, *substr;
> +	int64_t vid, vring_id;
> +
> +	struct rte_dma_info info;
> +	struct rte_dma_conf dev_config = { .nb_vchans = 1 };
> +	struct rte_dma_vchan_conf qconf = {
> +		.direction = RTE_DMA_DIR_MEM_TO_MEM,
> +		.nb_desc = DMA_RING_SIZE
> +	};
> +
> +	int dev_id;
> +	int ret = 0;
> +	uint16_t i = 0;
> +	char *dma_arg[MAX_VHOST_DEVICE];
> +	int args_nr;
> +
> +	while (isblank(*addrs))
> +		addrs++;
> +	if (*addrs == '\0') {
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	/* process DMA devices within bracket. */
> +	addrs++;
> +	substr = strtok(addrs, ";]");
> +	if (!substr) {
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	args_nr = rte_strsplit(substr, strlen(substr),
> +			dma_arg, MAX_VHOST_DEVICE, ',');
> +	if (args_nr <= 0) {
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	while (i < args_nr) {
> +		char *arg_temp = dma_arg[i];
> +		uint8_t sub_nr;
> +
> +		sub_nr = rte_strsplit(arg_temp, strlen(arg_temp), ptrs, 2, '@');
> +		if (sub_nr != 2) {
> +			ret = -1;
> +			goto out;
> +		}
> +
> +		start = strstr(ptrs[0], "txd");
> +		if (start == NULL) {
> +			ret = -1;
> +			goto out;
> +		}
> +
> +		start += 3;
> +		vid = strtol(start, &end, 0);
> +		if (end == start) {
> +			ret = -1;
> +			goto out;
> +		}
> +
> +		vring_id = 0 + VIRTIO_RXQ;
> +
> +		dev_id = rte_dma_get_dev_id_by_name(ptrs[1]);
> +		if (dev_id < 0) {
> +			RTE_LOG(ERR, VHOST_CONFIG, "Fail to find DMA %s.\n", ptrs[1]);
> +			ret = -1;
> +			goto out;
> +		} else if (is_dma_configured(dev_id)) {
> +			goto done;
> +		}
> +
> +		if (rte_dma_configure(dev_id, &dev_config) != 0) {
> +			RTE_LOG(ERR, VHOST_CONFIG, "Fail to configure DMA %d.\n", dev_id);
> +			ret = -1;
> +			goto out;
> +		}
> +
> +		if (rte_dma_vchan_setup(dev_id, 0, &qconf) != 0) {
> +			RTE_LOG(ERR, VHOST_CONFIG, "Fail to set up DMA %d.\n", dev_id);
> +			ret = -1;
> +			goto out;
> +		}
>   
> -	return -1;
> +		rte_dma_info_get(dev_id, &info);
> +		if (info.nb_vchans != 1) {
> +			RTE_LOG(ERR, VHOST_CONFIG, "DMA %d has no queues.\n", dev_id);
> +			ret = -1;
> +			goto out;
> +		}

So, I would call rte_dma_info_get() before calling rte_dma_vchan_setup()
to get desc number value working with the DMA device.

> +
> +		if (rte_dma_start(dev_id) != 0) {
> +			RTE_LOG(ERR, VHOST_CONFIG, "Fail to start DMA %u.\n", dev_id);
> +			ret = -1;
> +			goto out;
> +		}
> +
> +		dma_config[dma_count].dev_id = dev_id;
> +		dma_config[dma_count].max_vchans = 1;
> +		dma_config[dma_count++].max_desc = DMA_RING_SIZE;
> +
> +done:
> +		(dma_info + vid)->dmas[vring_id].dev_id = dev_id;
> +		i++;
> +	}
> +out:
> +	free(input);
> +	return ret;
>   }
>   
>   /*
> @@ -500,8 +628,6 @@ enum {
>   	OPT_CLIENT_NUM,
>   #define OPT_BUILTIN_NET_DRIVER  "builtin-net-driver"
>   	OPT_BUILTIN_NET_DRIVER_NUM,
> -#define OPT_DMA_TYPE            "dma-type"
> -	OPT_DMA_TYPE_NUM,
>   #define OPT_DMAS                "dmas"
>   	OPT_DMAS_NUM,
>   };
> @@ -539,8 +665,6 @@ us_vhost_parse_args(int argc, char **argv)
>   				NULL, OPT_CLIENT_NUM},
>   		{OPT_BUILTIN_NET_DRIVER, no_argument,
>   				NULL, OPT_BUILTIN_NET_DRIVER_NUM},
> -		{OPT_DMA_TYPE, required_argument,
> -				NULL, OPT_DMA_TYPE_NUM},
>   		{OPT_DMAS, required_argument,
>   				NULL, OPT_DMAS_NUM},
>   		{NULL, 0, 0, 0},
> @@ -661,10 +785,6 @@ us_vhost_parse_args(int argc, char **argv)
>   			}
>   			break;
>   
> -		case OPT_DMA_TYPE_NUM:
> -			dma_type = optarg;
> -			break;
> -
>   		case OPT_DMAS_NUM:
>   			if (open_dma(optarg) == -1) {
>   				RTE_LOG(INFO, VHOST_CONFIG,
> @@ -841,9 +961,10 @@ complete_async_pkts(struct vhost_dev *vdev)
>   {
>   	struct rte_mbuf *p_cpl[MAX_PKT_BURST];
>   	uint16_t complete_count;
> +	int16_t dma_id = dma_bind[vdev->vid].dmas[VIRTIO_RXQ].dev_id;
>   
>   	complete_count = rte_vhost_poll_enqueue_completed(vdev->vid,
> -					VIRTIO_RXQ, p_cpl, MAX_PKT_BURST);
> +					VIRTIO_RXQ, p_cpl, MAX_PKT_BURST, dma_id, 0);
>   	if (complete_count) {
>   		free_pkts(p_cpl, complete_count);
>   		__atomic_sub_fetch(&vdev->pkts_inflight, complete_count, __ATOMIC_SEQ_CST);
> @@ -883,11 +1004,12 @@ drain_vhost(struct vhost_dev *vdev)
>   
>   	if (builtin_net_driver) {
>   		ret = vs_enqueue_pkts(vdev, VIRTIO_RXQ, m, nr_xmit);
> -	} else if (async_vhost_driver) {
> +	} else if (dma_bind[vdev->vid].dmas[VIRTIO_RXQ].async_enabled) {
>   		uint16_t enqueue_fail = 0;
> +		int16_t dma_id = dma_bind[vdev->vid].dmas[VIRTIO_RXQ].dev_id;
>   
>   		complete_async_pkts(vdev);
> -		ret = rte_vhost_submit_enqueue_burst(vdev->vid, VIRTIO_RXQ, m, nr_xmit);
> +		ret = rte_vhost_submit_enqueue_burst(vdev->vid, VIRTIO_RXQ, m, nr_xmit, dma_id, 0);
>   		__atomic_add_fetch(&vdev->pkts_inflight, ret, __ATOMIC_SEQ_CST);
>   
>   		enqueue_fail = nr_xmit - ret;
> @@ -905,7 +1027,7 @@ drain_vhost(struct vhost_dev *vdev)
>   				__ATOMIC_SEQ_CST);
>   	}
>   
> -	if (!async_vhost_driver)
> +	if (!dma_bind[vdev->vid].dmas[VIRTIO_RXQ].async_enabled)
>   		free_pkts(m, nr_xmit);
>   }
>   
> @@ -1211,12 +1333,13 @@ drain_eth_rx(struct vhost_dev *vdev)
>   	if (builtin_net_driver) {
>   		enqueue_count = vs_enqueue_pkts(vdev, VIRTIO_RXQ,
>   						pkts, rx_count);
> -	} else if (async_vhost_driver) {
> +	} else if (dma_bind[vdev->vid].dmas[VIRTIO_RXQ].async_enabled) {
>   		uint16_t enqueue_fail = 0;
> +		int16_t dma_id = dma_bind[vdev->vid].dmas[VIRTIO_RXQ].dev_id;
>   
>   		complete_async_pkts(vdev);
>   		enqueue_count = rte_vhost_submit_enqueue_burst(vdev->vid,
> -					VIRTIO_RXQ, pkts, rx_count);
> +					VIRTIO_RXQ, pkts, rx_count, dma_id, 0);
>   		__atomic_add_fetch(&vdev->pkts_inflight, enqueue_count, __ATOMIC_SEQ_CST);
>   
>   		enqueue_fail = rx_count - enqueue_count;
> @@ -1235,7 +1358,7 @@ drain_eth_rx(struct vhost_dev *vdev)
>   				__ATOMIC_SEQ_CST);
>   	}
>   
> -	if (!async_vhost_driver)
> +	if (!dma_bind[vdev->vid].dmas[VIRTIO_RXQ].async_enabled)
>   		free_pkts(pkts, rx_count);
>   }
>   
> @@ -1387,18 +1510,20 @@ destroy_device(int vid)
>   		"(%d) device has been removed from data core\n",
>   		vdev->vid);
>   
> -	if (async_vhost_driver) {
> +	if (dma_bind[vid].dmas[VIRTIO_RXQ].async_enabled) {
>   		uint16_t n_pkt = 0;
> +		int16_t dma_id = dma_bind[vid].dmas[VIRTIO_RXQ].dev_id;
>   		struct rte_mbuf *m_cpl[vdev->pkts_inflight];
>   
>   		while (vdev->pkts_inflight) {
>   			n_pkt = rte_vhost_clear_queue_thread_unsafe(vid, VIRTIO_RXQ,
> -						m_cpl, vdev->pkts_inflight);
> +						m_cpl, vdev->pkts_inflight, dma_id, 0);
>   			free_pkts(m_cpl, n_pkt);
>   			__atomic_sub_fetch(&vdev->pkts_inflight, n_pkt, __ATOMIC_SEQ_CST);
>   		}
>   
>   		rte_vhost_async_channel_unregister(vid, VIRTIO_RXQ);
> +		dma_bind[vid].dmas[VIRTIO_RXQ].async_enabled = false;
>   	}
>   
>   	rte_free(vdev);
> @@ -1468,20 +1593,14 @@ new_device(int vid)
>   		"(%d) device has been added to data core %d\n",
>   		vid, vdev->coreid);
>   
> -	if (async_vhost_driver) {
> -		struct rte_vhost_async_config config = {0};
> -		struct rte_vhost_async_channel_ops channel_ops;
> -
> -		if (dma_type != NULL && strncmp(dma_type, "ioat", 4) == 0) {
> -			channel_ops.transfer_data = ioat_transfer_data_cb;
> -			channel_ops.check_completed_copies =
> -				ioat_check_completed_copies_cb;
> -
> -			config.features = RTE_VHOST_ASYNC_INORDER;
> +	if (dma_bind[vid].dmas[VIRTIO_RXQ].dev_id != INVALID_DMA_ID) {
> +		int ret;
>   
> -			return rte_vhost_async_channel_register(vid, VIRTIO_RXQ,
> -				config, &channel_ops);
> +		ret = rte_vhost_async_channel_register(vid, VIRTIO_RXQ);
> +		if (ret == 0) {
> +			dma_bind[vid].dmas[VIRTIO_RXQ].async_enabled = true;
>   		}
> +		return ret;
>   	}
>   
>   	return 0;
> @@ -1502,14 +1621,15 @@ vring_state_changed(int vid, uint16_t queue_id, int enable)
>   	if (queue_id != VIRTIO_RXQ)
>   		return 0;
>   
> -	if (async_vhost_driver) {
> +	if (dma_bind[vid].dmas[queue_id].async_enabled) {
>   		if (!enable) {
>   			uint16_t n_pkt = 0;
> +			int16_t dma_id = dma_bind[vid].dmas[VIRTIO_RXQ].dev_id;
>   			struct rte_mbuf *m_cpl[vdev->pkts_inflight];
>   
>   			while (vdev->pkts_inflight) {
>   				n_pkt = rte_vhost_clear_queue_thread_unsafe(vid, queue_id,
> -							m_cpl, vdev->pkts_inflight);
> +							m_cpl, vdev->pkts_inflight, dma_id, 0);
>   				free_pkts(m_cpl, n_pkt);
>   				__atomic_sub_fetch(&vdev->pkts_inflight, n_pkt, __ATOMIC_SEQ_CST);
>   			}
> @@ -1657,6 +1777,25 @@ create_mbuf_pool(uint16_t nr_port, uint32_t nr_switch_core, uint32_t mbuf_size,
>   		rte_exit(EXIT_FAILURE, "Cannot create mbuf pool\n");
>   }
>   
> +static void
> +init_dma(void)
> +{
> +	int i;
> +
> +	for (i = 0; i < MAX_VHOST_DEVICE; i++) {
> +		int j;
> +
> +		for (j = 0; j < RTE_MAX_QUEUES_PER_PORT * 2; j++) {
> +			dma_bind[i].dmas[j].dev_id = INVALID_DMA_ID;
> +			dma_bind[i].dmas[j].async_enabled = false;
> +		}
> +	}
> +
> +	for (i = 0; i < RTE_DMADEV_DEFAULT_MAX; i++) {
> +		dma_config[i].dev_id = INVALID_DMA_ID;
> +	}
> +}
> +
>   /*
>    * Main function, does initialisation and calls the per-lcore functions.
>    */
> @@ -1679,6 +1818,9 @@ main(int argc, char *argv[])
>   	argc -= ret;
>   	argv += ret;
>   
> +	/* initialize dma structures */
> +	init_dma();
> +
>   	/* parse app arguments */
>   	ret = us_vhost_parse_args(argc, argv);
>   	if (ret < 0)
> @@ -1754,6 +1896,20 @@ main(int argc, char *argv[])
>   	if (client_mode)
>   		flags |= RTE_VHOST_USER_CLIENT;
>   
> +	if (async_vhost_driver) {

You should be able to get rid off async_vhost_driver and instead rely on
dma_count.

> +		if (rte_vhost_async_dma_configure(dma_config, dma_count) < 0) {
> +			RTE_LOG(ERR, VHOST_PORT, "Failed to configure DMA in vhost.\n");
> +			for (i = 0; i < dma_count; i++) {
> +				if (dma_config[i].dev_id != INVALID_DMA_ID) {
> +					rte_dma_stop(dma_config[i].dev_id);
> +					dma_config[i].dev_id = INVALID_DMA_ID;
> +				}
> +			}
> +			dma_count = 0;
> +			async_vhost_driver = false;

Let's just exit the app if DMAs were provided in command line but cannot
be used.

> +		}
> +	}
> +
>   	/* Register vhost user driver to handle vhost messages. */
>   	for (i = 0; i < nb_sockets; i++) {
>   		char *file = socket_files + i * PATH_MAX;
> diff --git a/examples/vhost/main.h b/examples/vhost/main.h
> index e7b1ac60a6..b4a453e77e 100644
> --- a/examples/vhost/main.h
> +++ b/examples/vhost/main.h
> @@ -8,6 +8,7 @@
>   #include <sys/queue.h>
>   
>   #include <rte_ether.h>
> +#include <rte_pci.h>
>   
>   /* Macros for printing using RTE_LOG */
>   #define RTE_LOGTYPE_VHOST_CONFIG RTE_LOGTYPE_USER1
> @@ -79,6 +80,16 @@ struct lcore_info {
>   	struct vhost_dev_tailq_list vdev_list;
>   };
>   
> +struct dma_info {
> +	struct rte_pci_addr addr;
> +	int16_t dev_id;
> +	bool async_enabled;
> +};
> +
> +struct dma_for_vhost {
> +	struct dma_info dmas[RTE_MAX_QUEUES_PER_PORT * 2];
> +};
> +
>   /* we implement non-extra virtio net features */
>   #define VIRTIO_NET_FEATURES	0
>   
> diff --git a/examples/vhost/meson.build b/examples/vhost/meson.build
> index 3efd5e6540..87a637f83f 100644
> --- a/examples/vhost/meson.build
> +++ b/examples/vhost/meson.build
> @@ -12,13 +12,9 @@ if not is_linux
>   endif
>   
>   deps += 'vhost'
> +deps += 'dmadev'
>   allow_experimental_apis = true
>   sources = files(
>           'main.c',
>           'virtio_net.c',
>   )
> -
> -if dpdk_conf.has('RTE_RAW_IOAT')
> -    deps += 'raw_ioat'
> -    sources += files('ioat.c')
> -endif
> diff --git a/lib/vhost/meson.build b/lib/vhost/meson.build
> index cdb37a4814..8107329400 100644
> --- a/lib/vhost/meson.build
> +++ b/lib/vhost/meson.build
> @@ -33,7 +33,8 @@ headers = files(
>           'rte_vhost_async.h',
>           'rte_vhost_crypto.h',
>   )
> +
>   driver_sdk_headers = files(
>           'vdpa_driver.h',
>   )
> -deps += ['ethdev', 'cryptodev', 'hash', 'pci']
> +deps += ['ethdev', 'cryptodev', 'hash', 'pci', 'dmadev']
> diff --git a/lib/vhost/rte_vhost_async.h b/lib/vhost/rte_vhost_async.h
> index a87ea6ba37..23a7a2d8b3 100644
> --- a/lib/vhost/rte_vhost_async.h
> +++ b/lib/vhost/rte_vhost_async.h
> @@ -27,70 +27,12 @@ struct rte_vhost_iov_iter {
>   };
>   
>   /**
> - * dma transfer status
> + * DMA device information
>    */
> -struct rte_vhost_async_status {
> -	/** An array of application specific data for source memory */
> -	uintptr_t *src_opaque_data;
> -	/** An array of application specific data for destination memory */
> -	uintptr_t *dst_opaque_data;
> -};
> -
> -/**
> - * dma operation callbacks to be implemented by applications
> - */
> -struct rte_vhost_async_channel_ops {
> -	/**
> -	 * instruct async engines to perform copies for a batch of packets
> -	 *
> -	 * @param vid
> -	 *  id of vhost device to perform data copies
> -	 * @param queue_id
> -	 *  queue id to perform data copies
> -	 * @param iov_iter
> -	 *  an array of IOV iterators
> -	 * @param opaque_data
> -	 *  opaque data pair sending to DMA engine
> -	 * @param count
> -	 *  number of elements in the "descs" array
> -	 * @return
> -	 *  number of IOV iterators processed, negative value means error
> -	 */
> -	int32_t (*transfer_data)(int vid, uint16_t queue_id,
> -		struct rte_vhost_iov_iter *iov_iter,
> -		struct rte_vhost_async_status *opaque_data,
> -		uint16_t count);
> -	/**
> -	 * check copy-completed packets from the async engine
> -	 * @param vid
> -	 *  id of vhost device to check copy completion
> -	 * @param queue_id
> -	 *  queue id to check copy completion
> -	 * @param opaque_data
> -	 *  buffer to receive the opaque data pair from DMA engine
> -	 * @param max_packets
> -	 *  max number of packets could be completed
> -	 * @return
> -	 *  number of async descs completed, negative value means error
> -	 */
> -	int32_t (*check_completed_copies)(int vid, uint16_t queue_id,
> -		struct rte_vhost_async_status *opaque_data,
> -		uint16_t max_packets);
> -};
> -
> -/**
> - *  async channel features
> - */
> -enum {
> -	RTE_VHOST_ASYNC_INORDER = 1U << 0,
> -};
> -
> -/**
> - *  async channel configuration
> - */
> -struct rte_vhost_async_config {
> -	uint32_t features;
> -	uint32_t rsvd[2];
> +struct rte_vhost_async_dma_info {
> +	int16_t dev_id;	/* DMA device ID */
> +	uint16_t max_vchans;	/* max number of vchan */
> +	uint16_t max_desc;	/* max desc number of vchan */
>   };
>   
>   /**
> @@ -100,17 +42,11 @@ struct rte_vhost_async_config {
>    *  vhost device id async channel to be attached to
>    * @param queue_id
>    *  vhost queue id async channel to be attached to
> - * @param config
> - *  Async channel configuration structure
> - * @param ops
> - *  Async channel operation callbacks
>    * @return
>    *  0 on success, -1 on failures
>    */
>   __rte_experimental
> -int rte_vhost_async_channel_register(int vid, uint16_t queue_id,
> -	struct rte_vhost_async_config config,
> -	struct rte_vhost_async_channel_ops *ops);
> +int rte_vhost_async_channel_register(int vid, uint16_t queue_id);
>   
>   /**
>    * Unregister an async channel for a vhost queue
> @@ -136,17 +72,11 @@ int rte_vhost_async_channel_unregister(int vid, uint16_t queue_id);
>    *  vhost device id async channel to be attached to
>    * @param queue_id
>    *  vhost queue id async channel to be attached to
> - * @param config
> - *  Async channel configuration
> - * @param ops
> - *  Async channel operation callbacks
>    * @return
>    *  0 on success, -1 on failures
>    */
>   __rte_experimental
> -int rte_vhost_async_channel_register_thread_unsafe(int vid, uint16_t queue_id,
> -	struct rte_vhost_async_config config,
> -	struct rte_vhost_async_channel_ops *ops);
> +int rte_vhost_async_channel_register_thread_unsafe(int vid, uint16_t queue_id);
>   
>   /**
>    * Unregister an async channel for a vhost queue without performing any
> @@ -179,12 +109,17 @@ int rte_vhost_async_channel_unregister_thread_unsafe(int vid,
>    *  array of packets to be enqueued
>    * @param count
>    *  packets num to be enqueued
> + * @param dma_id
> + *  the identifier of the DMA device
> + * @param vchan
> + *  the identifier of virtual DMA channel
>    * @return
>    *  num of packets enqueued
>    */
>   __rte_experimental
>   uint16_t rte_vhost_submit_enqueue_burst(int vid, uint16_t queue_id,
> -		struct rte_mbuf **pkts, uint16_t count);
> +		struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
> +		uint16_t vchan);

Maybe using vchan_id would be clearer for the API user, same comment
below.

>   
>   /**
>    * This function checks async completion status for a specific vhost
> @@ -199,12 +134,17 @@ uint16_t rte_vhost_submit_enqueue_burst(int vid, uint16_t queue_id,
>    *  blank array to get return packet pointer
>    * @param count
>    *  size of the packet array
> + * @param dma_id
> + *  the identifier of the DMA device
> + * @param vchan
> + *  the identifier of virtual DMA channel
>    * @return
>    *  num of packets returned
>    */
>   __rte_experimental
>   uint16_t rte_vhost_poll_enqueue_completed(int vid, uint16_t queue_id,
> -		struct rte_mbuf **pkts, uint16_t count);
> +		struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
> +		uint16_t vchan);
>   
>   /**
>    * This function returns the amount of in-flight packets for the vhost
> @@ -235,11 +175,32 @@ int rte_vhost_async_get_inflight(int vid, uint16_t queue_id);
>    *  Blank array to get return packet pointer
>    * @param count
>    *  Size of the packet array
> + * @param dma_id
> + *  the identifier of the DMA device
> + * @param vchan
> + *  the identifier of virtual DMA channel
>    * @return
>    *  Number of packets returned
>    */
>   __rte_experimental
>   uint16_t rte_vhost_clear_queue_thread_unsafe(int vid, uint16_t queue_id,
> -		struct rte_mbuf **pkts, uint16_t count);
> +		struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
> +		uint16_t vchan);
> +/**
> + * The DMA vChannels used in asynchronous data path must be configured
> + * first. So this function needs to be called before enabling DMA
> + * acceleration for vring. If this function fails, asynchronous data path
> + * cannot be enabled for any vring further.
> + *
> + * @param dmas
> + *  DMA information
> + * @param count
> + *  Element number of 'dmas'
> + * @return
> + *  0 on success, and -1 on failure
> + */
> +__rte_experimental
> +int rte_vhost_async_dma_configure(struct rte_vhost_async_dma_info *dmas,
> +		uint16_t count);
>   
>   #endif /* _RTE_VHOST_ASYNC_H_ */
> diff --git a/lib/vhost/version.map b/lib/vhost/version.map
> index a7ef7f1976..1202ba9c1a 100644
> --- a/lib/vhost/version.map
> +++ b/lib/vhost/version.map
> @@ -84,6 +84,9 @@ EXPERIMENTAL {
>   
>   	# added in 21.11
>   	rte_vhost_get_monitor_addr;
> +
> +	# added in 22.03
> +	rte_vhost_async_dma_configure;
>   };
>   
>   INTERNAL {
> diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
> index 13a9bb9dd1..32f37f4851 100644
> --- a/lib/vhost/vhost.c
> +++ b/lib/vhost/vhost.c
> @@ -344,6 +344,7 @@ vhost_free_async_mem(struct vhost_virtqueue *vq)
>   		return;
>   
>   	rte_free(vq->async->pkts_info);
> +	rte_free(vq->async->pkts_cmpl_flag);
>   
>   	rte_free(vq->async->buffers_packed);
>   	vq->async->buffers_packed = NULL;
> @@ -1626,8 +1627,7 @@ rte_vhost_extern_callback_register(int vid,
>   }
>   
>   static __rte_always_inline int
> -async_channel_register(int vid, uint16_t queue_id,
> -		struct rte_vhost_async_channel_ops *ops)
> +async_channel_register(int vid, uint16_t queue_id)
>   {
>   	struct virtio_net *dev = get_device(vid);
>   	struct vhost_virtqueue *vq = dev->virtqueue[queue_id];
> @@ -1656,6 +1656,14 @@ async_channel_register(int vid, uint16_t queue_id,
>   		goto out_free_async;
>   	}
>   
> +	async->pkts_cmpl_flag = rte_zmalloc_socket(NULL, vq->size * sizeof(bool),
> +			RTE_CACHE_LINE_SIZE, node);
> +	if (!async->pkts_cmpl_flag) {
> +		VHOST_LOG_CONFIG(ERR, "failed to allocate async pkts_cmpl_flag (vid %d, qid: %d)\n",
> +				vid, queue_id);
> +		goto out_free_async;
> +	}
> +
>   	if (vq_is_packed(dev)) {
>   		async->buffers_packed = rte_malloc_socket(NULL,
>   				vq->size * sizeof(struct vring_used_elem_packed),
> @@ -1676,9 +1684,6 @@ async_channel_register(int vid, uint16_t queue_id,
>   		}
>   	}
>   
> -	async->ops.check_completed_copies = ops->check_completed_copies;
> -	async->ops.transfer_data = ops->transfer_data;
> -
>   	vq->async = async;
>   
>   	return 0;
> @@ -1691,15 +1696,13 @@ async_channel_register(int vid, uint16_t queue_id,
>   }
>   
>   int
> -rte_vhost_async_channel_register(int vid, uint16_t queue_id,
> -		struct rte_vhost_async_config config,
> -		struct rte_vhost_async_channel_ops *ops)
> +rte_vhost_async_channel_register(int vid, uint16_t queue_id)
>   {
>   	struct vhost_virtqueue *vq;
>   	struct virtio_net *dev = get_device(vid);
>   	int ret;
>   
> -	if (dev == NULL || ops == NULL)
> +	if (dev == NULL)
>   		return -1;
>   
>   	if (queue_id >= VHOST_MAX_VRING)
> @@ -1710,33 +1713,20 @@ rte_vhost_async_channel_register(int vid, uint16_t queue_id,
>   	if (unlikely(vq == NULL || !dev->async_copy))
>   		return -1;
>   
> -	if (unlikely(!(config.features & RTE_VHOST_ASYNC_INORDER))) {
> -		VHOST_LOG_CONFIG(ERR,
> -			"async copy is not supported on non-inorder mode "
> -			"(vid %d, qid: %d)\n", vid, queue_id);
> -		return -1;
> -	}
> -
> -	if (unlikely(ops->check_completed_copies == NULL ||
> -		ops->transfer_data == NULL))
> -		return -1;
> -
>   	rte_spinlock_lock(&vq->access_lock);
> -	ret = async_channel_register(vid, queue_id, ops);
> +	ret = async_channel_register(vid, queue_id);
>   	rte_spinlock_unlock(&vq->access_lock);
>   
>   	return ret;
>   }
>   
>   int
> -rte_vhost_async_channel_register_thread_unsafe(int vid, uint16_t queue_id,
> -		struct rte_vhost_async_config config,
> -		struct rte_vhost_async_channel_ops *ops)
> +rte_vhost_async_channel_register_thread_unsafe(int vid, uint16_t queue_id)
>   {
>   	struct vhost_virtqueue *vq;
>   	struct virtio_net *dev = get_device(vid);
>   
> -	if (dev == NULL || ops == NULL)
> +	if (dev == NULL)
>   		return -1;
>   
>   	if (queue_id >= VHOST_MAX_VRING)
> @@ -1747,18 +1737,7 @@ rte_vhost_async_channel_register_thread_unsafe(int vid, uint16_t queue_id,
>   	if (unlikely(vq == NULL || !dev->async_copy))
>   		return -1;
>   
> -	if (unlikely(!(config.features & RTE_VHOST_ASYNC_INORDER))) {
> -		VHOST_LOG_CONFIG(ERR,
> -			"async copy is not supported on non-inorder mode "
> -			"(vid %d, qid: %d)\n", vid, queue_id);
> -		return -1;
> -	}
> -
> -	if (unlikely(ops->check_completed_copies == NULL ||
> -		ops->transfer_data == NULL))
> -		return -1;
> -
> -	return async_channel_register(vid, queue_id, ops);
> +	return async_channel_register(vid, queue_id);
>   }
>   
>   int
> @@ -1835,6 +1814,83 @@ rte_vhost_async_channel_unregister_thread_unsafe(int vid, uint16_t queue_id)
>   	return 0;
>   }
>   
> +static __rte_always_inline void
> +vhost_free_async_dma_mem(void)
> +{
> +	uint16_t i;
> +
> +	for (i = 0; i < RTE_DMADEV_DEFAULT_MAX; i++) {
> +		struct async_dma_info *dma = &dma_copy_track[i];
> +		int16_t j;
> +
> +		if (dma->max_vchans == 0) {
> +			continue;
> +		}
> +
> +		for (j = 0; j < dma->max_vchans; j++) {
> +			rte_free(dma->vchans[j].metadata);
> +		}
> +		rte_free(dma->vchans);
> +		dma->vchans = NULL;
> +		dma->max_vchans = 0;
> +	}
> +}
> +
> +int
> +rte_vhost_async_dma_configure(struct rte_vhost_async_dma_info *dmas, uint16_t count)
> +{
> +	uint16_t i;
> +
> +	if (!dmas) {
> +		VHOST_LOG_CONFIG(ERR, "Invalid DMA configuration parameter.\n");
> +		return -1;
> +	}
> +
> +	for (i = 0; i < count; i++) {
> +		struct async_dma_vchan_info *vchans;
> +		int16_t dev_id;
> +		uint16_t max_vchans;
> +		uint16_t max_desc;
> +		uint16_t j;
> +
> +		dev_id = dmas[i].dev_id;
> +		max_vchans = dmas[i].max_vchans;
> +		max_desc = dmas[i].max_desc;
> +
> +		if (!rte_is_power_of_2(max_desc)) {
> +			max_desc = rte_align32pow2(max_desc);
> +		}

That will be problematic with CNXK driver that reports 15 as max_desc.

> +
> +		vchans = rte_zmalloc(NULL, sizeof(struct async_dma_vchan_info) * max_vchans,
> +				RTE_CACHE_LINE_SIZE);
> +		if (vchans == NULL) {
> +			VHOST_LOG_CONFIG(ERR, "Failed to allocate vchans for dma-%d."
> +					" Cannot enable async data-path.\n", dev_id);
> +			vhost_free_async_dma_mem();
> +			return -1;
> +		}
> +
> +		for (j = 0; j < max_vchans; j++) {
> +			vchans[j].metadata = rte_zmalloc(NULL, sizeof(bool *) * max_desc,
> +					RTE_CACHE_LINE_SIZE);

That's quite a huge allocation (4096 * 8B per channel).

> +			if (!vchans[j].metadata) {
> +				VHOST_LOG_CONFIG(ERR, "Failed to allocate metadata for "
> +						"dma-%d vchan-%u\n", dev_id, j);
> +				vhost_free_async_dma_mem();
> +				return -1;
> +			}
> +
> +			vchans[j].ring_size = max_desc;
> +			vchans[j].ring_mask = max_desc - 1;
> +		}
> +
> +		dma_copy_track[dev_id].vchans = vchans;
> +		dma_copy_track[dev_id].max_vchans = max_vchans;
> +	}
> +
> +	return 0;
> +}
> +
>   int
>   rte_vhost_async_get_inflight(int vid, uint16_t queue_id)
>   {
> diff --git a/lib/vhost/vhost.h b/lib/vhost/vhost.h
> index 7085e0885c..d9bda34e11 100644
> --- a/lib/vhost/vhost.h
> +++ b/lib/vhost/vhost.h
> @@ -19,6 +19,7 @@
>   #include <rte_ether.h>
>   #include <rte_rwlock.h>
>   #include <rte_malloc.h>
> +#include <rte_dmadev.h>
>   
>   #include "rte_vhost.h"
>   #include "rte_vdpa.h"
> @@ -50,6 +51,7 @@
>   
>   #define VHOST_MAX_ASYNC_IT (MAX_PKT_BURST)
>   #define VHOST_MAX_ASYNC_VEC 2048
> +#define VHOST_ASYNC_DMA_BATCHING_SIZE 32
>   
>   #define PACKED_DESC_ENQUEUE_USED_FLAG(w)	\
>   	((w) ? (VRING_DESC_F_AVAIL | VRING_DESC_F_USED | VRING_DESC_F_WRITE) : \
> @@ -119,6 +121,41 @@ struct vring_used_elem_packed {
>   	uint32_t count;
>   };
>   
> +struct async_dma_vchan_info {
> +	/* circular array to track copy metadata */
> +	bool **metadata;
> +
> +	/* max elements in 'metadata' */
> +	uint16_t ring_size;
> +	/* ring index mask for 'metadata' */
> +	uint16_t ring_mask;

Given cnxk, we cannot use a mask as the ring size may not be a pow2.

> +
> +	/* batching copies before a DMA doorbell */
> +	uint16_t nr_batching;
> +
> +	/**
> +	 * DMA virtual channel lock. Although it is able to bind DMA
> +	 * virtual channels to data plane threads, vhost control plane
> +	 * thread could call data plane functions too, thus causing
> +	 * DMA device contention.
> +	 *
> +	 * For example, in VM exit case, vhost control plane thread needs
> +	 * to clear in-flight packets before disable vring, but there could
> +	 * be anotther data plane thread is enqueuing packets to the same
> +	 * vring with the same DMA virtual channel. But dmadev PMD functions
> +	 * are lock-free, so the control plane and data plane threads
> +	 * could operate the same DMA virtual channel at the same time.
> +	 */
> +	rte_spinlock_t dma_lock;
> +};
> +
> +struct async_dma_info {
> +	uint16_t max_vchans;
> +	struct async_dma_vchan_info *vchans;
> +};
> +
> +extern struct async_dma_info dma_copy_track[RTE_DMADEV_DEFAULT_MAX];
> +
>   /**
>    * inflight async packet information
>    */
> @@ -129,9 +166,6 @@ struct async_inflight_info {
>   };
>   
>   struct vhost_async {
> -	/* operation callbacks for DMA */
> -	struct rte_vhost_async_channel_ops ops;
> -
>   	struct rte_vhost_iov_iter iov_iter[VHOST_MAX_ASYNC_IT];
>   	struct rte_vhost_iovec iovec[VHOST_MAX_ASYNC_VEC];
>   	uint16_t iter_idx;
> @@ -139,6 +173,19 @@ struct vhost_async {
>   
>   	/* data transfer status */
>   	struct async_inflight_info *pkts_info;
> +	/**
> +	 * packet reorder array. "true" indicates that DMA
> +	 * device completes all copies for the packet.
> +	 *
> +	 * Note that this array could be written by multiple
> +	 * threads at the same time. For example, two threads
> +	 * enqueue packets to the same virtqueue with their
> +	 * own DMA devices. However, since offloading is
> +	 * per-packet basis, each packet flag will only be
> +	 * written by one thread. And single byte write is
> +	 * atomic, so no lock is needed.
> +	 */

The vq->access_lock is held by the threads (directly or indirectly)
anyway, right?

> +	bool *pkts_cmpl_flag;
>   	uint16_t pkts_idx;
>   	uint16_t pkts_inflight_n;
>   	union {
> diff --git a/lib/vhost/virtio_net.c b/lib/vhost/virtio_net.c
> index b3d954aab4..9f81fc9733 100644
> --- a/lib/vhost/virtio_net.c
> +++ b/lib/vhost/virtio_net.c
> @@ -11,6 +11,7 @@
>   #include <rte_net.h>
>   #include <rte_ether.h>
>   #include <rte_ip.h>
> +#include <rte_dmadev.h>
>   #include <rte_vhost.h>
>   #include <rte_tcp.h>
>   #include <rte_udp.h>
> @@ -25,6 +26,9 @@
>   
>   #define MAX_BATCH_LEN 256
>   
> +/* DMA device copy operation tracking array. */
> +struct async_dma_info dma_copy_track[RTE_DMADEV_DEFAULT_MAX];
> +
>   static  __rte_always_inline bool
>   rxvq_is_mergeable(struct virtio_net *dev)
>   {
> @@ -43,6 +47,108 @@ is_valid_virt_queue_idx(uint32_t idx, int is_tx, uint32_t nr_vring)
>   	return (is_tx ^ (idx & 1)) == 0 && idx < nr_vring;
>   }
>   
> +static __rte_always_inline uint16_t
> +vhost_async_dma_transfer(struct vhost_virtqueue *vq, int16_t dma_id,
> +		uint16_t vchan, uint16_t head_idx,
> +		struct rte_vhost_iov_iter *pkts, uint16_t nr_pkts)
> +{
> +	struct async_dma_vchan_info *dma_info = &dma_copy_track[dma_id].vchans[vchan];
> +	uint16_t ring_mask = dma_info->ring_mask;
> +	uint16_t pkt_idx;
> +
> +	rte_spinlock_lock(&dma_info->dma_lock);
> +
> +	for (pkt_idx = 0; pkt_idx < nr_pkts; pkt_idx++) {
> +		struct rte_vhost_iovec *iov = pkts[pkt_idx].iov;
> +		int copy_idx = 0;
> +		uint16_t nr_segs = pkts[pkt_idx].nr_segs;
> +		uint16_t i;
> +
> +		if (rte_dma_burst_capacity(dma_id, vchan) < nr_segs) {
> +			goto out;
> +		}
> +
> +		for (i = 0; i < nr_segs; i++) {
> +			/**
> +			 * We have checked the available space before submit copies to DMA
> +			 * vChannel, so we don't handle error here.
> +			 */
> +			copy_idx = rte_dma_copy(dma_id, vchan, (rte_iova_t)iov[i].src_addr,
> +					(rte_iova_t)iov[i].dst_addr, iov[i].len,
> +					RTE_DMA_OP_FLAG_LLC);
> +
> +			/**
> +			 * Only store packet completion flag address in the last copy's
> +			 * slot, and other slots are set to NULL.
> +			 */
> +			if (unlikely(i == (nr_segs - 1))) {

I don't think using unlikely() is appropriate here, as single-segment 
packets are more the norm than the exception, isn't?

> +				dma_info->metadata[copy_idx & ring_mask] =
dma_info->metadata[copy_idx % ring_size] instead.
> +					&vq->async->pkts_cmpl_flag[head_idx % vq->size];
> +			}
> +		}
> +
> +		dma_info->nr_batching += nr_segs;
> +		if (unlikely(dma_info->nr_batching >= VHOST_ASYNC_DMA_BATCHING_SIZE)) {
> +			rte_dma_submit(dma_id, vchan);
> +			dma_info->nr_batching = 0;
> +		}
> +
> +		head_idx++;
> +	}
> +
> +out:
> +	if (dma_info->nr_batching > 0) {
> +		rte_dma_submit(dma_id, vchan);
> +		dma_info->nr_batching = 0;
> +	}
> +	rte_spinlock_unlock(&dma_info->dma_lock);
> +
> +	return pkt_idx;
> +}
> +
> +static __rte_always_inline uint16_t
> +vhost_async_dma_check_completed(int16_t dma_id, uint16_t vchan, uint16_t max_pkts)
> +{
> +	struct async_dma_vchan_info *dma_info = &dma_copy_track[dma_id].vchans[vchan];
> +	uint16_t ring_mask = dma_info->ring_mask;
> +	uint16_t last_idx = 0;
> +	uint16_t nr_copies;
> +	uint16_t copy_idx;
> +	uint16_t i;
> +
> +	rte_spinlock_lock(&dma_info->dma_lock);
> +
> +	/**
> +	 * Since all memory is pinned and addresses should be valid,
> +	 * we don't check errors.

Please, check for errors to ease debugging, you can for now add a debug
print if error is set which would print rte_errno. And once we have my
Vhost statistics series in, I could add a counter for it.

The DMA device could be in a bad state for other reason than unpinned 
memory or unvalid addresses.

> +	 */
> +	nr_copies = rte_dma_completed(dma_id, vchan, max_pkts, &last_idx, NULL);

Are you sure max_pkts is valid here as a packet could contain several
segments?

> +	if (nr_copies == 0) {
> +		goto out;
> +	}
> +
> +	copy_idx = last_idx - nr_copies + 1;
> +	for (i = 0; i < nr_copies; i++) {
> +		bool *flag;
> +
> +		flag = dma_info->metadata[copy_idx & ring_mask];

dma_info->metadata[copy_idx % ring_size]

> +		if (flag) {
> +			/**
> +			 * Mark the packet flag as received. The flag
> +			 * could belong to another virtqueue but write
> +			 * is atomic.
> +			 */
> +			*flag = true;
> +			dma_info->metadata[copy_idx & ring_mask] = NULL;

dma_info->metadata[copy_idx % ring_size]

> +		}
> +		copy_idx++;
> +	}
> +
> +out:
> +	rte_spinlock_unlock(&dma_info->dma_lock);
> +	return nr_copies;

> +}
> +
>   static inline void
>   do_data_copy_enqueue(struct virtio_net *dev, struct vhost_virtqueue *vq)
>   {
> @@ -1449,9 +1555,9 @@ store_dma_desc_info_packed(struct vring_used_elem_packed *s_ring,
>   }
>   
>   static __rte_noinline uint32_t
> -virtio_dev_rx_async_submit_split(struct virtio_net *dev,
> -	struct vhost_virtqueue *vq, uint16_t queue_id,
> -	struct rte_mbuf **pkts, uint32_t count)
> +virtio_dev_rx_async_submit_split(struct virtio_net *dev, struct vhost_virtqueue *vq,
> +		uint16_t queue_id, struct rte_mbuf **pkts, uint32_t count,
> +		int16_t dma_id, uint16_t vchan)
>   {
>   	struct buf_vector buf_vec[BUF_VECTOR_MAX];
>   	uint32_t pkt_idx = 0;
> @@ -1503,17 +1609,16 @@ virtio_dev_rx_async_submit_split(struct virtio_net *dev,
>   	if (unlikely(pkt_idx == 0))
>   		return 0;
>   
> -	n_xfer = async->ops.transfer_data(dev->vid, queue_id, async->iov_iter, 0, pkt_idx);
> -	if (unlikely(n_xfer < 0)) {
> -		VHOST_LOG_DATA(ERR, "(%d) %s: failed to transfer data for queue id %d.\n",
> -				dev->vid, __func__, queue_id);
> -		n_xfer = 0;
> -	}
> +	n_xfer = vhost_async_dma_transfer(vq, dma_id, vchan, async->pkts_idx, async->iov_iter,
> +			pkt_idx);
>   
>   	pkt_err = pkt_idx - n_xfer;
>   	if (unlikely(pkt_err)) {
>   		uint16_t num_descs = 0;
>   
> +		VHOST_LOG_DATA(DEBUG, "(%d) %s: failed to transfer %u packets for queue %u.\n",
> +				dev->vid, __func__, pkt_err, queue_id);
> +
>   		/* update number of completed packets */
>   		pkt_idx = n_xfer;
>   
> @@ -1656,13 +1761,13 @@ dma_error_handler_packed(struct vhost_virtqueue *vq, uint16_t slot_idx,
>   }
>   
>   static __rte_noinline uint32_t
> -virtio_dev_rx_async_submit_packed(struct virtio_net *dev,
> -	struct vhost_virtqueue *vq, uint16_t queue_id,
> -	struct rte_mbuf **pkts, uint32_t count)
> +virtio_dev_rx_async_submit_packed(struct virtio_net *dev, struct vhost_virtqueue *vq,
> +		uint16_t queue_id, struct rte_mbuf **pkts, uint32_t count,
> +		int16_t dma_id, uint16_t vchan)
>   {
>   	uint32_t pkt_idx = 0;
>   	uint32_t remained = count;
> -	int32_t n_xfer;
> +	uint16_t n_xfer;
>   	uint16_t num_buffers;
>   	uint16_t num_descs;
>   
> @@ -1670,6 +1775,7 @@ virtio_dev_rx_async_submit_packed(struct virtio_net *dev,
>   	struct async_inflight_info *pkts_info = async->pkts_info;
>   	uint32_t pkt_err = 0;
>   	uint16_t slot_idx = 0;
> +	uint16_t head_idx = async->pkts_idx % vq->size;
>   
>   	do {
>   		rte_prefetch0(&vq->desc_packed[vq->last_avail_idx]);
> @@ -1694,19 +1800,17 @@ virtio_dev_rx_async_submit_packed(struct virtio_net *dev,
>   	if (unlikely(pkt_idx == 0))
>   		return 0;
>   
> -	n_xfer = async->ops.transfer_data(dev->vid, queue_id, async->iov_iter, 0, pkt_idx);
> -	if (unlikely(n_xfer < 0)) {
> -		VHOST_LOG_DATA(ERR, "(%d) %s: failed to transfer data for queue id %d.\n",
> -				dev->vid, __func__, queue_id);
> -		n_xfer = 0;
> -	}
> -
> -	pkt_err = pkt_idx - n_xfer;
> +	n_xfer = vhost_async_dma_transfer(vq, dma_id, vchan, head_idx,
> +			async->iov_iter, pkt_idx);
>   
>   	async_iter_reset(async);
>   
> -	if (unlikely(pkt_err))
> +	pkt_err = pkt_idx - n_xfer;
> +	if (unlikely(pkt_err)) {
> +		VHOST_LOG_DATA(DEBUG, "(%d) %s: failed to transfer %u packets for queue %u.\n",
> +				dev->vid, __func__, pkt_err, queue_id);
>   		dma_error_handler_packed(vq, slot_idx, pkt_err, &pkt_idx);
> +	}
>   
>   	if (likely(vq->shadow_used_idx)) {
>   		/* keep used descriptors. */
> @@ -1826,28 +1930,37 @@ write_back_completed_descs_packed(struct vhost_virtqueue *vq,
>   
>   static __rte_always_inline uint16_t
>   vhost_poll_enqueue_completed(struct virtio_net *dev, uint16_t queue_id,
> -		struct rte_mbuf **pkts, uint16_t count)
> +		struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
> +		uint16_t vchan)
>   {
>   	struct vhost_virtqueue *vq = dev->virtqueue[queue_id];
>   	struct vhost_async *async = vq->async;
>   	struct async_inflight_info *pkts_info = async->pkts_info;
> -	int32_t n_cpl;
> +	uint16_t nr_cpl_pkts = 0;
>   	uint16_t n_descs = 0, n_buffers = 0;
>   	uint16_t start_idx, from, i;
>   
> -	n_cpl = async->ops.check_completed_copies(dev->vid, queue_id, 0, count);
> -	if (unlikely(n_cpl < 0)) {
> -		VHOST_LOG_DATA(ERR, "(%d) %s: failed to check completed copies for queue id %d.\n",
> -				dev->vid, __func__, queue_id);
> -		return 0;
> -	}
> -
> -	if (n_cpl == 0)
> -		return 0;
> +	/* Check completed copies for the given DMA vChannel */
> +	vhost_async_dma_check_completed(dma_id, vchan, count);
>   
>   	start_idx = async_get_first_inflight_pkt_idx(vq);
>   
> -	for (i = 0; i < n_cpl; i++) {
> +	/**
> +	 * Calculate the number of copy completed packets.
> +	 * Note that there may be completed packets even if
> +	 * no copies are reported done by the given DMA vChannel,
> +	 * as DMA vChannels could be shared by other threads.
> +	 */
> +	from = start_idx;
> +	while (vq->async->pkts_cmpl_flag[from] && count--) {
> +		vq->async->pkts_cmpl_flag[from] = false;
> +		from++;
> +		if (from >= vq->size)
> +			from -= vq->size;
> +		nr_cpl_pkts++;
> +	}
> +
> +	for (i = 0; i < nr_cpl_pkts; i++) {
>   		from = (start_idx + i) % vq->size;
>   		/* Only used with packed ring */
>   		n_buffers += pkts_info[from].nr_buffers;
> @@ -1856,7 +1969,7 @@ vhost_poll_enqueue_completed(struct virtio_net *dev, uint16_t queue_id,
>   		pkts[i] = pkts_info[from].mbuf;
>   	}
>   
> -	async->pkts_inflight_n -= n_cpl;
> +	async->pkts_inflight_n -= nr_cpl_pkts;
>   
>   	if (likely(vq->enabled && vq->access_ok)) {
>   		if (vq_is_packed(dev)) {
> @@ -1877,12 +1990,13 @@ vhost_poll_enqueue_completed(struct virtio_net *dev, uint16_t queue_id,
>   		}
>   	}
>   
> -	return n_cpl;
> +	return nr_cpl_pkts;
>   }
>   
>   uint16_t
>   rte_vhost_poll_enqueue_completed(int vid, uint16_t queue_id,
> -		struct rte_mbuf **pkts, uint16_t count)
> +		struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
> +		uint16_t vchan)
>   {
>   	struct virtio_net *dev = get_device(vid);
>   	struct vhost_virtqueue *vq;
> @@ -1908,7 +2022,7 @@ rte_vhost_poll_enqueue_completed(int vid, uint16_t queue_id,
>   
>   	rte_spinlock_lock(&vq->access_lock);
>   
> -	n_pkts_cpl = vhost_poll_enqueue_completed(dev, queue_id, pkts, count);
> +	n_pkts_cpl = vhost_poll_enqueue_completed(dev, queue_id, pkts, count, dma_id, vchan);
>   
>   	rte_spinlock_unlock(&vq->access_lock);
>   
> @@ -1917,7 +2031,8 @@ rte_vhost_poll_enqueue_completed(int vid, uint16_t queue_id,
>   
>   uint16_t
>   rte_vhost_clear_queue_thread_unsafe(int vid, uint16_t queue_id,
> -		struct rte_mbuf **pkts, uint16_t count)
> +		struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
> +		uint16_t vchan)
>   {
>   	struct virtio_net *dev = get_device(vid);
>   	struct vhost_virtqueue *vq;
> @@ -1941,14 +2056,14 @@ rte_vhost_clear_queue_thread_unsafe(int vid, uint16_t queue_id,
>   		return 0;
>   	}
>   
> -	n_pkts_cpl = vhost_poll_enqueue_completed(dev, queue_id, pkts, count);
> +	n_pkts_cpl = vhost_poll_enqueue_completed(dev, queue_id, pkts, count, dma_id, vchan);
>   
>   	return n_pkts_cpl;
>   }
>   
>   static __rte_always_inline uint32_t
>   virtio_dev_rx_async_submit(struct virtio_net *dev, uint16_t queue_id,
> -	struct rte_mbuf **pkts, uint32_t count)
> +	struct rte_mbuf **pkts, uint32_t count, int16_t dma_id, uint16_t vchan)
>   {
>   	struct vhost_virtqueue *vq;
>   	uint32_t nb_tx = 0;
> @@ -1980,10 +2095,10 @@ virtio_dev_rx_async_submit(struct virtio_net *dev, uint16_t queue_id,
>   
>   	if (vq_is_packed(dev))
>   		nb_tx = virtio_dev_rx_async_submit_packed(dev, vq, queue_id,
> -				pkts, count);
> +				pkts, count, dma_id, vchan);
>   	else
>   		nb_tx = virtio_dev_rx_async_submit_split(dev, vq, queue_id,
> -				pkts, count);
> +				pkts, count, dma_id, vchan);
>   
>   out:
>   	if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM))
> @@ -1997,7 +2112,8 @@ virtio_dev_rx_async_submit(struct virtio_net *dev, uint16_t queue_id,
>   
>   uint16_t
>   rte_vhost_submit_enqueue_burst(int vid, uint16_t queue_id,
> -		struct rte_mbuf **pkts, uint16_t count)
> +		struct rte_mbuf **pkts, uint16_t count, int16_t dma_id,
> +		uint16_t vchan)
>   {
>   	struct virtio_net *dev = get_device(vid);
>   
> @@ -2011,7 +2127,7 @@ rte_vhost_submit_enqueue_burst(int vid, uint16_t queue_id,
>   		return 0;
>   	}
>   
> -	return virtio_dev_rx_async_submit(dev, queue_id, pkts, count);
> +	return virtio_dev_rx_async_submit(dev, queue_id, pkts, count, dma_id, vchan);
>   }
>   
>   static inline bool