On Tue, Feb 21, 2023 at 6:36 AM Jason Wang <jasow...@redhat.com> wrote:
>
>
> 在 2023/2/8 17:42, Eugenio Pérez 写道:
> > The function vhost.c:vhost_dev_stop calls vhost operation
> > vhost_dev_start(false). In the case of vdpa it totally reset and wipes
> > the device, making the fetching of the vring base (virtqueue state) totally
> > useless.
> >
> > The kernel backend does not use vhost_dev_start vhost op callback, but
> > vhost-user do. A patch to make vhost_user_dev_start more similar to vdpa
> > is desirable, but it can be added on top.
> >
> > Signed-off-by: Eugenio Pérez <epere...@redhat.com>
> > ---
> > include/hw/virtio/vhost-backend.h | 4 ++++
> > hw/virtio/vhost-vdpa.c | 22 ++++++++++++++++------
> > hw/virtio/vhost.c | 3 +++
> > 3 files changed, 23 insertions(+), 6 deletions(-)
> >
> > diff --git a/include/hw/virtio/vhost-backend.h
> > b/include/hw/virtio/vhost-backend.h
> > index c5ab49051e..ec3fbae58d 100644
> > --- a/include/hw/virtio/vhost-backend.h
> > +++ b/include/hw/virtio/vhost-backend.h
> > @@ -130,6 +130,9 @@ typedef bool (*vhost_force_iommu_op)(struct vhost_dev
> > *dev);
> >
> > typedef int (*vhost_set_config_call_op)(struct vhost_dev *dev,
> > int fd);
> > +
> > +typedef void (*vhost_reset_status_op)(struct vhost_dev *dev);
> > +
> > typedef struct VhostOps {
> > VhostBackendType backend_type;
> > vhost_backend_init vhost_backend_init;
> > @@ -177,6 +180,7 @@ typedef struct VhostOps {
> > vhost_get_device_id_op vhost_get_device_id;
> > vhost_force_iommu_op vhost_force_iommu;
> > vhost_set_config_call_op vhost_set_config_call;
> > + vhost_reset_status_op vhost_reset_status;
> > } VhostOps;
> >
> > int vhost_backend_update_device_iotlb(struct vhost_dev *dev,
> > diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> > index cbbe92ffe8..26e38a6aab 100644
> > --- a/hw/virtio/vhost-vdpa.c
> > +++ b/hw/virtio/vhost-vdpa.c
> > @@ -1152,14 +1152,23 @@ static int vhost_vdpa_dev_start(struct vhost_dev
> > *dev, bool started)
> > if (started) {
> > memory_listener_register(&v->listener, &address_space_memory);
> > return vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_DRIVER_OK);
> > - } else {
> > - vhost_vdpa_reset_device(dev);
> > - vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE |
> > - VIRTIO_CONFIG_S_DRIVER);
> > - memory_listener_unregister(&v->listener);
> > + }
> >
> > - return 0;
> > + return 0;
> > +}
> > +
> > +static void vhost_vdpa_reset_status(struct vhost_dev *dev)
> > +{
> > + struct vhost_vdpa *v = dev->opaque;
> > +
> > + if (dev->vq_index + dev->nvqs != dev->vq_index_end) {
> > + return;
> > }
> > +
> > + vhost_vdpa_reset_device(dev);
> > + vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE |
> > + VIRTIO_CONFIG_S_DRIVER);
> > + memory_listener_unregister(&v->listener);
> > }
> >
> > static int vhost_vdpa_set_log_base(struct vhost_dev *dev, uint64_t base,
> > @@ -1346,4 +1355,5 @@ const VhostOps vdpa_ops = {
> > .vhost_vq_get_addr = vhost_vdpa_vq_get_addr,
> > .vhost_force_iommu = vhost_vdpa_force_iommu,
> > .vhost_set_config_call = vhost_vdpa_set_config_call,
> > + .vhost_reset_status = vhost_vdpa_reset_status,
> > };
> > diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> > index eb8c4c378c..a266396576 100644
> > --- a/hw/virtio/vhost.c
> > +++ b/hw/virtio/vhost.c
> > @@ -2049,6 +2049,9 @@ void vhost_dev_stop(struct vhost_dev *hdev,
> > VirtIODevice *vdev, bool vrings)
> > hdev->vqs + i,
> > hdev->vq_index + i);
> > }
> > + if (hdev->vhost_ops->vhost_reset_status) {
> > + hdev->vhost_ops->vhost_reset_status(hdev);
> > + }
>
>
> This looks racy, if we don't suspend/reset the device, device can move
> last_avail_idx even after get_vring_base()?
>
> Instead of doing things like this, should we fallback to
> virtio_queue_restore_last_avail_idx() in this case?
>
Right, we can track if the device is suspended / SVQ and then return
an error in vring_get_base if it is not. Would that work?
Thanks!
> Thanks
>
>
> >
> > if (vhost_dev_has_iommu(hdev)) {
> > if (hdev->vhost_ops->vhost_set_iotlb_callback) {
>
