Re: [PATCH for 8.1 v2 2/6] vdpa: add vhost_vdpa_reset_status_fd

[Eugenio Perez Martin]

On Tue, Mar 28, 2023 at 8:53 AM Jason Wang <jasowang@redhat.com> wrote:
>
> On Fri, Mar 24, 2023 at 3:54 AM Eugenio Pérez <eperezma@redhat.com> wrote:
> >
>
> The title needs some tweak, I think the more appropriate one is
> "introduce vhost_vdpa_call_fd()"
>

We can do it otherwise, but the function exported in the
include/hw/virtio/vhost-vdpa.h file is vhost_vdpa_reset_status_fd. I'd
consider vhost_vdpa_call_fd an implementation detail, only in
hw/virtio/vhost-vdpa.c file.

> > This allows to reset a vhost-vdpa device from external subsystems like
> > vhost-net, since it does not have any struct vhost_dev by the time we
> > need to use it.
>
> This part needs some clarification, vhost-net should be initialized
> after vhost_dev, so it can access its parent vhost_dev structure?
>

Next patches probes CVQ vring groups at initialization net-vdpa
initialization time (net_init_vhost_vdpa). It already fetches things
like device features using raw ioctl() calls because vhost_dev is
still not available.

> >
> > It is used in subsequent patches to negotiate features
> > and probe for CVQ ASID isolation.
> >
> > Signed-off-by: Eugenio Pérez <eperezma@redhat.com>
> > ---
> >  include/hw/virtio/vhost-vdpa.h |  1 +
> >  hw/virtio/vhost-vdpa.c         | 58 +++++++++++++++++++++++-----------
> >  2 files changed, 41 insertions(+), 18 deletions(-)
> >
> > diff --git a/include/hw/virtio/vhost-vdpa.h b/include/hw/virtio/vhost-vdpa.h
> > index c278a2a8de..28de7da91e 100644
> > --- a/include/hw/virtio/vhost-vdpa.h
> > +++ b/include/hw/virtio/vhost-vdpa.h
> > @@ -54,6 +54,7 @@ typedef struct vhost_vdpa {
> >      VhostVDPAHostNotifier notifier[VIRTIO_QUEUE_MAX];
> >  } VhostVDPA;
> >
> > +void vhost_vdpa_reset_status_fd(int fd);
> >  int vhost_vdpa_get_iova_range(int fd, struct vhost_vdpa_iova_range 
> > *iova_range);
> >
> >  int vhost_vdpa_dma_map(struct vhost_vdpa *v, uint32_t asid, hwaddr iova,
> > diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> > index bbabea18f3..7a2053b8d9 100644
> > --- a/hw/virtio/vhost-vdpa.c
> > +++ b/hw/virtio/vhost-vdpa.c
> > @@ -335,38 +335,45 @@ static const MemoryListener 
> > vhost_vdpa_memory_listener = {
> >      .region_del = vhost_vdpa_listener_region_del,
> >  };
> >
> > -static int vhost_vdpa_call(struct vhost_dev *dev, unsigned long int 
> > request,
> > -                             void *arg)
> > +static int vhost_vdpa_dev_fd(const struct vhost_dev *dev)
> >  {
> >      struct vhost_vdpa *v = dev->opaque;
> > -    int fd = v->device_fd;
> > -    int ret;
> >
> >      assert(dev->vhost_ops->backend_type == VHOST_BACKEND_TYPE_VDPA);
> > +    return v->device_fd;
> > +}
> > +
> > +static int vhost_vdpa_call_fd(int fd, unsigned long int request, void *arg)
> > +{
> > +    int ret = ioctl(fd, request, arg);
> >
> > -    ret = ioctl(fd, request, arg);
> >      return ret < 0 ? -errno : ret;
> >  }
> >
> > -static int vhost_vdpa_add_status(struct vhost_dev *dev, uint8_t status)
> > +static int vhost_vdpa_call(struct vhost_dev *dev, unsigned long int 
> > request,
> > +                           void *arg)
> > +{
> > +    return vhost_vdpa_call_fd(vhost_vdpa_dev_fd(dev), request, arg);
> > +}
> > +
> > +static int vhost_vdpa_add_status_fd(int fd, uint8_t status)
> >  {
> >      uint8_t s;
> >      int ret;
> >
> > -    trace_vhost_vdpa_add_status(dev, status);
> > -    ret = vhost_vdpa_call(dev, VHOST_VDPA_GET_STATUS, &s);
>
> We can stick a vhost_vdpa_call() function that calls
> vhost_vdpa_call_fd() then we can avoid a lot of changes?
>

I don't follow this. vhost_vdpa_call already calls vhost_vdpa_call_fd.

Thanks!

> Thanks
>
> > +    ret = vhost_vdpa_call_fd(fd, VHOST_VDPA_GET_STATUS, &s);
> >      if (ret < 0) {
> >          return ret;
> >      }
> >
> >      s |= status;
> >
> > -    ret = vhost_vdpa_call(dev, VHOST_VDPA_SET_STATUS, &s);
> > +    ret = vhost_vdpa_call_fd(fd, VHOST_VDPA_SET_STATUS, &s);
> >      if (ret < 0) {
> >          return ret;
> >      }
> >
> > -    ret = vhost_vdpa_call(dev, VHOST_VDPA_GET_STATUS, &s);
> > +    ret = vhost_vdpa_call_fd(fd, VHOST_VDPA_GET_STATUS, &s);
> >      if (ret < 0) {
> >          return ret;
> >      }
> > @@ -378,6 +385,12 @@ static int vhost_vdpa_add_status(struct vhost_dev 
> > *dev, uint8_t status)
> >      return 0;
> >  }
> >
> > +static int vhost_vdpa_add_status(struct vhost_dev *dev, uint8_t status)
> > +{
> > +    trace_vhost_vdpa_add_status(dev, status);
> > +    return vhost_vdpa_add_status_fd(vhost_vdpa_dev_fd(dev), status);
> > +}
> > +
> >  int vhost_vdpa_get_iova_range(int fd, struct vhost_vdpa_iova_range 
> > *iova_range)
> >  {
> >      int ret = ioctl(fd, VHOST_VDPA_GET_IOVA_RANGE, iova_range);
> > @@ -709,16 +722,20 @@ static int vhost_vdpa_get_device_id(struct vhost_dev 
> > *dev,
> >      return ret;
> >  }
> >
> > +static int vhost_vdpa_reset_device_fd(int fd)
> > +{
> > +    uint8_t status = 0;
> > +
> > +    return vhost_vdpa_call_fd(fd, VHOST_VDPA_SET_STATUS, &status);
> > +}
> > +
> >  static int vhost_vdpa_reset_device(struct vhost_dev *dev)
> >  {
> >      struct vhost_vdpa *v = dev->opaque;
> > -    int ret;
> > -    uint8_t status = 0;
> >
> > -    ret = vhost_vdpa_call(dev, VHOST_VDPA_SET_STATUS, &status);
> > -    trace_vhost_vdpa_reset_device(dev);
> >      v->suspended = false;
> > -    return ret;
> > +    trace_vhost_vdpa_reset_device(dev);
> > +    return vhost_vdpa_reset_device_fd(vhost_vdpa_dev_fd(dev));
> >  }
> >
> >  static int vhost_vdpa_get_vq_index(struct vhost_dev *dev, int idx)
> > @@ -1170,6 +1187,13 @@ static int vhost_vdpa_dev_start(struct vhost_dev 
> > *dev, bool started)
> >      return 0;
> >  }
> >
> > +void vhost_vdpa_reset_status_fd(int fd)
> > +{
> > +    vhost_vdpa_reset_device_fd(fd);
> > +    vhost_vdpa_add_status_fd(fd, VIRTIO_CONFIG_S_ACKNOWLEDGE |
> > +                                 VIRTIO_CONFIG_S_DRIVER);
> > +}
> > +
> >  static void vhost_vdpa_reset_status(struct vhost_dev *dev)
> >  {
> >      struct vhost_vdpa *v = dev->opaque;
> > @@ -1178,9 +1202,7 @@ static void vhost_vdpa_reset_status(struct vhost_dev 
> > *dev)
> >          return;
> >      }
> >
> > -    vhost_vdpa_reset_device(dev);
> > -    vhost_vdpa_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE |
> > -                               VIRTIO_CONFIG_S_DRIVER);
> > +    vhost_vdpa_reset_status_fd(vhost_vdpa_dev_fd(dev));
> >      memory_listener_unregister(&v->listener);
> >  }
> >
> > --
> > 2.31.1
> >
>