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

[Xuan Zhuo <xuanzhuo@linux.alibaba.com>]

On Thu, 22 Sep 2022 09:35:35 +0000, "Xia, Chenbo" <chenbo.xia@intel.com> wrote:
> > -----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?


Yes, we are simultaneously pushing this feature to QEMU.

We have a patch for v3, maybe you missed it.

Thanks.


>
> 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
>