RE: [RFC 22/27] vhost: add VDUSE events handler

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

> -----Original Message-----
> From: Maxime Coquelin <maxime.coquelin@redhat.com>
> Sent: Friday, March 31, 2023 11:43 PM
> To: dev@dpdk.org; david.marchand@redhat.com; Xia, Chenbo
> <chenbo.xia@intel.com>; mkp@redhat.com; fbl@redhat.com;
> jasowang@redhat.com; Liang, Cunming <cunming.liang@intel.com>; Xie, Yongji
> <xieyongji@bytedance.com>; echaudro@redhat.com; eperezma@redhat.com;
> amorenoz@redhat.com
> Cc: Maxime Coquelin <maxime.coquelin@redhat.com>
> Subject: [RFC 22/27] vhost: add VDUSE events handler
> 
> This patch makes use of Vhost lib's FD manager to install
> a handler for VDUSE events occurring on the VDUSE device FD.
> 
> Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
> ---
>  lib/vhost/vduse.c | 102 ++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 102 insertions(+)
> 
> diff --git a/lib/vhost/vduse.c b/lib/vhost/vduse.c
> index afa8a39498..2a183130d3 100644
> --- a/lib/vhost/vduse.c
> +++ b/lib/vhost/vduse.c
> @@ -17,6 +17,7 @@
> 
>  #include <rte_common.h>
> 
> +#include "fd_man.h"
>  #include "iotlb.h"
>  #include "vduse.h"
>  #include "vhost.h"
> @@ -32,6 +33,27 @@
>  				(1ULL << VIRTIO_F_IN_ORDER) | \
>  				(1ULL << VIRTIO_F_IOMMU_PLATFORM))
> 
> +struct vduse {
> +	struct fdset fdset;
> +};
> +
> +static struct vduse vduse = {
> +	.fdset = {
> +		.fd = { [0 ... MAX_FDS - 1] = {-1, NULL, NULL, NULL, 0} },
> +		.fd_mutex = PTHREAD_MUTEX_INITIALIZER,
> +		.fd_pooling_mutex = PTHREAD_MUTEX_INITIALIZER,
> +		.num = 0
> +	},
> +};
> +
> +static bool vduse_events_thread;
> +
> +static const char * const vduse_reqs_str[] = {
> +	"VDUSE_GET_VQ_STATE",
> +	"VDUSE_SET_STATUS",
> +	"VDUSE_UPDATE_IOTLB",
> +};
> +
>  static int
>  vduse_inject_irq(struct virtio_net *dev, struct vhost_virtqueue *vq)
>  {
> @@ -105,16 +127,84 @@ static struct vhost_backend_ops vduse_backend_ops =
> {
>  	.inject_irq = vduse_inject_irq,
>  };
> 
> +static void
> +vduse_events_handler(int fd, void *arg, int *remove __rte_unused)
> +{
> +	struct virtio_net *dev = arg;
> +	struct vduse_dev_request req;
> +	struct vduse_dev_response resp;
> +	int ret;
> +
> +	memset(&resp, 0, sizeof(resp));
> +
> +	ret = read(fd, &req, sizeof(req));
> +	if (ret < 0) {
> +		VHOST_LOG_CONFIG(dev->ifname, ERR, "Failed to read
> request: %s\n",
> +				strerror(errno));
> +		return;
> +	} else if (ret < (int)sizeof(req)) {
> +		VHOST_LOG_CONFIG(dev->ifname, ERR, "Incomplete to read
> request %d\n", ret);
> +		return;
> +	}
> +
> +	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
> +
> +	VHOST_LOG_CONFIG(dev->ifname, INFO, "New request: %s (%u)\n",
> +			req.type < RTE_DIM(vduse_reqs_str) ?
> +			vduse_reqs_str[req.type] : "Unknown",
> +			req.type);
> +
> +	switch (req.type) {
> +	default:
> +		resp.result = VDUSE_REQ_RESULT_FAILED;
> +		break;
> +	}
> +
> +	pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL);
> +
> +	resp.request_id = req.request_id;
> +
> +	ret = write(dev->vduse_dev_fd, &resp, sizeof(resp));
> +	if (ret != sizeof(resp)) {
> +		VHOST_LOG_CONFIG(dev->ifname, ERR, "Failed to write
> response %s\n",
> +				strerror(errno));
> +		return;
> +	}
> +}
> +
>  int
>  vduse_device_create(const char *path)
>  {
>  	int control_fd, dev_fd, vid, ret;
> +	pthread_t fdset_tid;
>  	uint32_t i;
>  	struct virtio_net *dev;
>  	uint64_t ver = VHOST_VDUSE_API_VERSION;
>  	struct vduse_dev_config *dev_config = NULL;
>  	const char *name = path + strlen("/dev/vduse/");
> 
> +	/* If first device, create events dispatcher thread */
> +	if (vduse_events_thread == false) {
> +		/**
> +		 * create a pipe which will be waited by poll and notified to
> +		 * rebuild the wait list of poll.
> +		 */
> +		if (fdset_pipe_init(&vduse.fdset) < 0) {
> +			VHOST_LOG_CONFIG(path, ERR, "failed to create pipe for
> vduse fdset\n");
> +			return -1;
> +		}
> +
> +		ret = rte_ctrl_thread_create(&fdset_tid, "vduse-events", NULL,
> +				fdset_event_dispatch, &vduse.fdset);
> +		if (ret != 0) {
> +			VHOST_LOG_CONFIG(path, ERR, "failed to create vduse
> fdset handling thread\n");
> +			fdset_pipe_uninit(&vduse.fdset);
> +			return -1;
> +		}
> +
> +		vduse_events_thread = true;
> +	}
> +
>  	control_fd = open(VDUSE_CTRL_PATH, O_RDWR);
>  	if (control_fd < 0) {
>  		VHOST_LOG_CONFIG(name, ERR, "Failed to open %s: %s\n",
> @@ -198,6 +288,13 @@ vduse_device_create(const char *path)
>  		}
>  	}
> 
> +	ret = fdset_add(&vduse.fdset, dev->vduse_dev_fd,
> vduse_events_handler, NULL, dev);
> +	if (ret) {
> +		VHOST_LOG_CONFIG(name, ERR, "Failed to add fd %d to vduse
> fdset\n",
> +				dev->vduse_dev_fd);
> +		goto out_dev_destroy;
> +	}
> +
>  	free(dev_config);
> 
>  	return 0;
> @@ -236,11 +333,16 @@ vduse_device_destroy(const char *path)
>  	if (vid == RTE_MAX_VHOST_DEVICE)
>  		return -1;
> 
> +	fdset_del(&vduse.fdset, dev->vduse_dev_fd);
> +
>  	if (dev->vduse_dev_fd >= 0) {
>  		close(dev->vduse_dev_fd);
>  		dev->vduse_dev_fd = -1;
>  	}
> 
> +	sleep(2); //ToDo: Need to rework fdman to ensure the deleted FD is
> no
> +		  //more being polled, otherwise VDUSE_DESTROY_DEV will fail.
> +
>  	if (dev->vduse_ctrl_fd >= 0) {
>  		ret = ioctl(dev->vduse_ctrl_fd, VDUSE_DESTROY_DEV, name);
>  		if (ret)
> --
> 2.39.2

Reviewed-by: Chenbo Xia <chenbo.xia@intel.com>