Hi Cheng & Jiayu,
> -----Original Message-----
> From: Jiang, Cheng1 <cheng1.ji...@intel.com>
> Sent: Friday, July 16, 2021 3:25 PM
> To: maxime.coque...@redhat.com; Xia, Chenbo <chenbo....@intel.com>
> Cc: dev@dpdk.org; Hu, Jiayu <jiayu...@intel.com>; Yang, YvonneX
> <yvonnex.y...@intel.com>
> Subject: [PATCH v5 3/5] vhost: handle memory hotplug for async vhost
>
> From: Jiayu Hu <jiayu...@intel.com>
>
> When the guest memory is hotplugged, the vhost application which
> enables DMA acceleration must stop DMA transfers before the vhost
> re-maps the guest memory.
>
> This patch is to notify the vhost application of stopping DMA
> transfers.
>
> Signed-off-by: Jiayu Hu <jiayu...@intel.com>
> ---
> lib/vhost/vhost_user.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
> index 031c578e54..39e8432d1c 100644
> --- a/lib/vhost/vhost_user.c
> +++ b/lib/vhost/vhost_user.c
> @@ -1275,6 +1275,15 @@ vhost_user_set_mem_table(struct virtio_net **pdev,
> struct VhostUserMsg *msg,
> vdpa_dev->ops->dev_close(dev->vid);
> dev->flags &= ~VIRTIO_DEV_VDPA_CONFIGURED;
> }
> +
> + /* notify the backend application to stop DMA transfers */
Backend application -> vhost application
> + if (dev->async_copy && dev->notify_ops->vring_state_changed) {
> + for (i = 0; i < dev->nr_vring; i++) {
> + dev->notify_ops->vring_state_changed(dev->vid,
> + i, 0);
> + }
> + }
> +
In this case, I think app will never know the vring is enabled again with memory
table updated.
Thanks,
Chenbo
> free_mem_region(dev);
> rte_free(dev->mem);
> dev->mem = NULL;
> --
> 2.29.2
