Re: [RFC PATCH 15/18] vdpa: add vhost_vdpa_load_setup

[Si-Wei Liu]

On 10/19/2023 7:34 AM, Eugenio Pérez wrote:
Callers can use this function to setup the incoming migration.

Signed-off-by: Eugenio Pérez <epere...@redhat.com>
---
  include/hw/virtio/vhost-vdpa.h |  7 +++++++
  hw/virtio/vhost-vdpa.c         | 17 ++++++++++++++++-
  2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h
index 8f54e5edd4..edc08b7a02 100644
--- a/include/hw/virtio/vhost-vdpa.h
+++ b/include/hw/virtio/vhost-vdpa.h
@@ -45,6 +45,12 @@ typedef struct vhost_vdpa_shared {
  
      bool iotlb_batch_begin_sent;
  
+    /*
+     * The memory listener has been registered, so DMA maps have been sent to
+     * the device.
+     */
+    bool listener_registered;
+
      /* Vdpa must send shadow addresses as IOTLB key for data queues, not GPA 
*/
      bool shadow_data;
  } VhostVDPAShared;
@@ -73,6 +79,7 @@ int vhost_vdpa_dma_map(VhostVDPAShared *s, uint32_t asid, 
hwaddr iova,
                         hwaddr size, void *vaddr, bool readonly);
  int vhost_vdpa_dma_unmap(VhostVDPAShared *s, uint32_t asid, hwaddr iova,
                           hwaddr size);
+int vhost_vdpa_load_setup(VhostVDPAShared *s, AddressSpace *dma_as);
  
  typedef struct vdpa_iommu {
      VhostVDPAShared *dev_shared;
diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
index cc252fc2d8..bfbe4673af 100644
--- a/hw/virtio/vhost-vdpa.c
+++ b/hw/virtio/vhost-vdpa.c
@@ -1325,7 +1325,9 @@ static int vhost_vdpa_dev_start(struct vhost_dev *dev, 
bool started)
                           "IOMMU and try again");
              return -1;
          }
-        memory_listener_register(&v->shared->listener, dev->vdev->dma_as);
+        if (!v->shared->listener_registered) {
+            memory_listener_register(&v->shared->listener, dev->vdev->dma_as);
+        }
Set listener_registered to true after registration; in addition, it 
looks like the memory_listener_unregister in vhost_vdpa_reset_status 
doesn't clear the listener_registered flag after unregistration. This 
code path can be called during SVQ switching, if not doing so mapping 
can't be added back after a couple rounds of SVQ switching or live 
migration.

-Siwei

  
          return vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
      }
@@ -1528,3 +1530,16 @@ const VhostOps vdpa_ops = {
          .vhost_set_config_call = vhost_vdpa_set_config_call,
          .vhost_reset_status = vhost_vdpa_reset_status,
  };
+
+int vhost_vdpa_load_setup(VhostVDPAShared *shared, AddressSpace *dma_as)
+{
+    uint8_t s = VIRTIO_CONFIG_S_ACKNOWLEDGE | VIRTIO_CONFIG_S_DRIVER;
+    int r = ioctl(shared->device_fd, VHOST_VDPA_SET_STATUS, &s);
+    if (unlikely(r < 0)) {
+        return r;
+    }
+
+    memory_listener_register(&shared->listener, dma_as);
+    shared->listener_registered = true;
+    return 0;
+}