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

["Hu, Jiayu" <jiayu.hu@intel.com>]

Hi Chenbo,

Please see replies inline.

Thanks,
Jiayu

> -----Original Message-----
> From: Xia, Chenbo <chenbo.xia@intel.com>
> > 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
> > +#define DMA_RING_SIZE 4096
> > +
> > +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;
> > +		}
> > +	}
> > +	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;
> 
> No need to introduce vring_id, it's always VIRTIO_RXQ

I will remove it later.

> 
> > +
> > +		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;
> > +		}
> > +
> 
> Please call rte_dma_info_get before configure to make sure
> info.max_vchans >=1

Do you suggest to use "rte_dma_info_get() and info.max_vchans=0" to indicate
the device is not configured, rather than using is_dma_configure()?

> 
> > +		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);
> 
> Then the above means the number of vchan is not configured.
> 
> > +			ret = -1;
> > +			goto out;
> > +		}
> > +
> > +		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) {
> > +		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;
> > +		}
> > +	}
> > +
> >  	/* 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);
> 
> All dma_id in the API should be uint16_t. Otherwise you need to check if valid.

Yes, you are right. Although dma_id is defined as int16_t and DMA library checks
if it is valid, vhost doesn't handle DMA failure and we need to make sure dma_id
is valid before using it. And even if vhost handles DMA error, a better place to check
invalid dma_id is before passing it to DMA library too. I will add the check later.

> 
> >
> >  /**
> >   * 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);
> 
> I think based on current design, vhost can use every vchan if user app let it.
> So the max_desc and max_vchans can just be got from dmadev APIs? Then
> there's
> no need to introduce the new ABI struct rte_vhost_async_dma_info.

Yes, no need to introduce struct rte_vhost_async_dma_info. We can either use
struct rte_dma_info which is suggested by Maxime, or query from dma library
via device id. Since dma device configuration is left to applications, I prefer to
use rte_dma_info directly. How do you think?

> 
> And about max_desc, I see the dmadev lib, you can get vchan's max_desc
> but you
> may use a nb_desc (<= max_desc) to configure vchanl. And IIUC, vhost wants
> to
> know the nb_desc instead of max_desc?

True, nb_desc is better than max_desc. But dma library doesn’t provide function
to query nb_desc for every vchannel. And rte_dma_info cannot be used in
rte_vhost_async_dma_configure(), if vhost uses nb_desc. So the only way is
to require users to provide nb_desc for every vchannel, and it will introduce
a new struct. Is it really needed?

> 
> >
> >  #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);
> 
> qid: %u
> 
> > +		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);
> > +		}
> 
> I think when aligning to power of 2, it should exceed not max_desc?

Aligned max_desc is used to allocate context tracking array. We only need
to guarantee the size of the array for every vchannel is >= max_desc. So it's
OK to have greater array size than max_desc.

> And based on above comment, if this max_desc is nb_desc configured for
> vchanl, you should just make sure the nb_desc be power-of-2.
> 
> > +
> > +		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);
> > +			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;
> 
> If the metadata will only be flags, maybe just use some
> name called XXX_flag

Sure, I will rename it.

> 
> > +
> > +	/* max elements in 'metadata' */
> > +	uint16_t ring_size;
> > +	/* ring index mask for 'metadata' */
> > +	uint16_t ring_mask;
> > +
> > +	/* 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.
> > +	 */
> > +	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);
> 
> This assumes rte_dma_copy will always succeed if there's available space.
> 
> But the API doxygen says:
> 
> * @return
>  *   - 0..UINT16_MAX: index of enqueued job.
>  *   - -ENOSPC: if no space left to enqueue.
>  *   - other values < 0 on failure.
> 
> So it should consider other vendor-specific errors.

Error handling is not free here. Specifically, SW fallback is a way to handle failed
copy operations. But it requires vhost to track VA for every source and destination
buffer for every copy. DMA library uses IOVA, so vhost only prepares IOVA for copies of
every packet in async data-path. In the case of IOVA as PA, the prepared IOVAs cannot
be used as SW fallback, which means vhost needs to store VA for every copy of every
packet too, even if there no errors will happen or IOVA is VA.

I am thinking that the only usable DMA engines in vhost are CBDMA and DSA, is it worth
the cost for "future HW"? If there will be other vendor's HW in future, is it OK to add the
support later? Or is there any way to get VA from IOVA?

Thanks,
Jiayu
> 
> Thanks,
> Chenbo
> 
>