vhost: handle memory hotplug for async vhost

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.hu@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
index 31300e1..433f412 100644 (file)
--- a/lib/vhost/vhost_user.c
+++ b/lib/vhost/vhost_user.c
@@ -1248,6 +1248,7 @@ vhost_user_set_mem_table(struct virtio_net **pdev, struct VhostUserMsg *msg,
        int numa_node = SOCKET_ID_ANY;
        uint64_t mmap_offset;
        uint32_t i;
+       bool async_notify = false;
 
        if (validate_msg_fds(msg, memory->nregions) != 0)
                return RTE_VHOST_MSG_RESULT_ERR;
@@ -1275,6 +1276,16 @@ 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 vhost application to stop DMA transfers */
+               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);
+                       }
+                       async_notify = true;
+               }
+
                free_mem_region(dev);
                rte_free(dev->mem);
                dev->mem = NULL;
@@ -1371,6 +1382,11 @@ vhost_user_set_mem_table(struct virtio_net **pdev, struct VhostUserMsg *msg,
 
        dump_guest_pages(dev);
 
+       if (async_notify) {
+               for (i = 0; i < dev->nr_vring; i++)
+                       dev->notify_ops->vring_state_changed(dev->vid, i, 1);
+       }
+
        return RTE_VHOST_MSG_RESULT_OK;
 
 free_mem_table: