RE: [PATCH v2 2/2] vhost: introduce VHOST_USER_RESET_VRING

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

> -----Original Message-----
> From: Kangjie Xu <kangjie.xu@linux.alibaba.com>
> Sent: Monday, September 5, 2022 11:48 AM
> To: maxime.coquelin@redhat.com; Xia, Chenbo <chenbo.xia@intel.com>
> Cc: dev@dpdk.org; xuanzhuo@linux.alibaba.com; hengqi@linux.alibaba.com;
> jasonwang@redhat.com; mst@redhat.com
> Subject: [PATCH v2 2/2] vhost: introduce VHOST_USER_RESET_VRING
> 
> To support the reset operation for an individual virtqueue, we
> introduce a new message VHOST_USER_RESET_VRING. When the feature
> VIRTIO_F_RING_RESET feature has been successfully negotiated, This
> message is submitted by the front-end to reset an individual
> virtqueue to initial states in the back-end. The reply is needed
> to ensure that the reset operation is complete.

completed

> 
> Signed-off-by: Kangjie Xu <kangjie.xu@linux.alibaba.com>
> Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> ---
>  lib/vhost/vhost.c      |  2 +-
>  lib/vhost/vhost.h      |  1 +
>  lib/vhost/vhost_user.c | 27 ++++++++++++++++++++++++++-
>  lib/vhost/vhost_user.h |  1 +
>  4 files changed, 29 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/vhost/vhost.c b/lib/vhost/vhost.c
> index 60cb05a0ff..215a1ca355 100644
> --- a/lib/vhost/vhost.c
> +++ b/lib/vhost/vhost.c
> @@ -610,7 +610,7 @@ init_vring_queue(struct virtio_net *dev, uint32_t
> vring_idx)
>  	vhost_user_iotlb_init(dev, vring_idx);
>  }
> 
> -static void
> +void
>  reset_vring_queue(struct virtio_net *dev, uint32_t vring_idx)
>  {
>  	struct vhost_virtqueue *vq;
> diff --git a/lib/vhost/vhost.h b/lib/vhost/vhost.h
> index 76461a3406..eccb52842d 100644
> --- a/lib/vhost/vhost.h
> +++ b/lib/vhost/vhost.h
> @@ -791,6 +791,7 @@ get_device(int vid)
> 
>  int vhost_new_device(void);
>  void cleanup_device(struct virtio_net *dev, int destroy);
> +void reset_vring_queue(struct virtio_net *dev, uint32_t vring_idx);
>  void reset_device(struct virtio_net *dev);
>  void vhost_destroy_device(int);
>  void vhost_destroy_device_notify(struct virtio_net *dev);
> diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
> index 4ad28bac45..5f7743d9d9 100644
> --- a/lib/vhost/vhost_user.c
> +++ b/lib/vhost/vhost_user.c
> @@ -2771,6 +2771,30 @@ vhost_user_set_status(struct virtio_net **pdev,
>  	return RTE_VHOST_MSG_RESULT_OK;
>  }
> 
> +static int
> +vhost_user_reset_vring(struct virtio_net **pdev,
> +			struct vhu_msg_context *ctx __rte_unused,
> +			int main_fd __rte_unused)
> +{
> +	struct virtio_net *dev = *pdev;
> +	int index = (int)ctx->msg.payload.state.index;

Why not just use unsigned int?

> +
> +	VHOST_LOG_CONFIG(dev->ifname, INFO, "reset queue: queue idx: %d\n",
> index);
> +
> +	if (!(dev->features & (1ULL << VIRTIO_F_RING_RESET))) {
> +		return RTE_VHOST_MSG_RESULT_ERR;
> +	}

braces {} are not necessary for single statement blocks

> +
> +	dev->virtqueue[index]->enabled = false;
> +	reset_vring_queue(dev, index);
> +
> +	ctx->msg.payload.state.num = 0;
> +	ctx->msg.size = sizeof(ctx->msg.payload.u64);
> +	ctx->fd_num = 0;
> +
> +	return RTE_VHOST_MSG_RESULT_REPLY;
> +}

IIUC, before this handler, we need to lock the queue? Using vhost_user_lock_all_queue_pairs

BTW, is this support merged in QEMU now? I remember for similar cases,
we wait for QEMU to merge first and then merge in DPDK.

Maxime, do I remember this correctly?

Thanks,
Chenbo

> +
>  #define VHOST_MESSAGE_HANDLERS \
>  VHOST_MESSAGE_HANDLER(VHOST_USER_NONE, NULL, false) \
>  VHOST_MESSAGE_HANDLER(VHOST_USER_GET_FEATURES, vhost_user_get_features,
> false) \
> @@ -2803,7 +2827,8 @@ VHOST_MESSAGE_HANDLER(VHOST_USER_POSTCOPY_END,
> vhost_user_postcopy_end, false) \
>  VHOST_MESSAGE_HANDLER(VHOST_USER_GET_INFLIGHT_FD,
> vhost_user_get_inflight_fd, false) \
>  VHOST_MESSAGE_HANDLER(VHOST_USER_SET_INFLIGHT_FD,
> vhost_user_set_inflight_fd, true) \
>  VHOST_MESSAGE_HANDLER(VHOST_USER_SET_STATUS, vhost_user_set_status, false)
> \
> -VHOST_MESSAGE_HANDLER(VHOST_USER_GET_STATUS, vhost_user_get_status, false)
> +VHOST_MESSAGE_HANDLER(VHOST_USER_GET_STATUS, vhost_user_get_status, false)
> \
> +VHOST_MESSAGE_HANDLER(VHOST_USER_RESET_VRING, vhost_user_reset_vring,
> false)
> 
>  #define VHOST_MESSAGE_HANDLER(id, handler, accepts_fd) \
>  	[id] = { #id, handler, accepts_fd },
> diff --git a/lib/vhost/vhost_user.h b/lib/vhost/vhost_user.h
> index 8ecca68597..51cb2fc74a 100644
> --- a/lib/vhost/vhost_user.h
> +++ b/lib/vhost/vhost_user.h
> @@ -60,6 +60,7 @@ typedef enum VhostUserRequest {
>  	VHOST_USER_SET_INFLIGHT_FD = 32,
>  	VHOST_USER_SET_STATUS = 39,
>  	VHOST_USER_GET_STATUS = 40,
> +	VHOST_USER_RESET_VRING = 41
>  } VhostUserRequest;
> 
>  typedef enum VhostUserSlaveRequest {
> --
> 2.32.0