Jason Wang
2021-Sep-09 09:28 UTC
[PATCH 5/6] vdpa: add get_vq_num_unchangeable callback in vdpa_config_ops
On Thu, Sep 9, 2021 at 4:02 PM Wu Zongyong <wuzongyong at linux.alibaba.com> wrote:> > On Thu, Sep 09, 2021 at 10:55:03AM +0800, Jason Wang wrote: > > On Wed, Sep 8, 2021 at 8:23 PM Wu Zongyong <wuzongyong at linux.alibaba.com> wrote: > > > > > > This new callback is used to indicate whether the vring size can be > > > change or not. It is useful when we have a legacy virtio pci device as > > > the vdpa device for there is no way to negotiate the vring num by the > > > specification. > > > > So I'm not sure it's worth bothering. E.g what if we just fail > > VHOST_SET_VRING_NUM it the value doesn't match what hardware has? > > > > Thanks > > > I think we should not call VHOST_SET_VRING_NUM in that case. > > If the hardware reports that the virtqueue size cannot be changed, we > should call VHOST_GET_VRING_NUM to get the static virtqueue size > firstly, then allocate the same size memory for the virtqueues and write > the address to hardware finally. > > For QEMU, we will ignore the properties rx/tx_queue_size and just get it > from the hardware if this new callback return true.This will break live migration. My understanding is that we can advertise those capability/limitation via the netlink management protocol then management layer can choose to use the correct queue size. Thanks> > What do you think? > > > > > > Signed-off-by: Wu Zongyong <wuzongyong at linux.alibaba.com> > > > --- > > > drivers/vhost/vdpa.c | 19 +++++++++++++++++++ > > > drivers/virtio/virtio_vdpa.c | 5 ++++- > > > include/linux/vdpa.h | 4 ++++ > > > include/uapi/linux/vhost.h | 2 ++ > > > 4 files changed, 29 insertions(+), 1 deletion(-) > > > > > > diff --git a/drivers/vhost/vdpa.c b/drivers/vhost/vdpa.c > > > index 9479f7f79217..2204d27d1e5d 100644 > > > --- a/drivers/vhost/vdpa.c > > > +++ b/drivers/vhost/vdpa.c > > > @@ -350,6 +350,22 @@ static long vhost_vdpa_get_iova_range(struct vhost_vdpa *v, u32 __user *argp) > > > return 0; > > > } > > > > > > +static long vhost_vdpa_get_vring_num_unchangeable(struct vhost_vdpa *v, > > > + u32 __user *argp) > > > +{ > > > + struct vdpa_device *vdpa = v->vdpa; > > > + const struct vdpa_config_ops *ops = vdpa->config; > > > + bool unchangeable = false; > > > + > > > + if (ops->get_vq_num_unchangeable) > > > + unchangeable = ops->get_vq_num_unchangeable(vdpa); > > > + > > > + if (copy_to_user(argp, &unchangeable, sizeof(unchangeable))) > > > + return -EFAULT; > > > + > > > + return 0; > > > +} > > > + > > > static long vhost_vdpa_vring_ioctl(struct vhost_vdpa *v, unsigned int cmd, > > > void __user *argp) > > > { > > > @@ -487,6 +503,9 @@ static long vhost_vdpa_unlocked_ioctl(struct file *filep, > > > case VHOST_VDPA_GET_IOVA_RANGE: > > > r = vhost_vdpa_get_iova_range(v, argp); > > > break; > > > + case VHOST_VDPA_GET_VRING_NUM_UNCHANGEABLE: > > > + r = vhost_vdpa_get_vring_num_unchangeable(v, argp); > > > + break; > > > default: > > > r = vhost_dev_ioctl(&v->vdev, cmd, argp); > > > if (r == -ENOIOCTLCMD) > > > diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c > > > index 72eaef2caeb1..afb47465307a 100644 > > > --- a/drivers/virtio/virtio_vdpa.c > > > +++ b/drivers/virtio/virtio_vdpa.c > > > @@ -146,6 +146,7 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index, > > > struct vdpa_vq_state state = {0}; > > > unsigned long flags; > > > u32 align, num; > > > + bool may_reduce_num = true; > > > int err; > > > > > > if (!name) > > > @@ -171,8 +172,10 @@ virtio_vdpa_setup_vq(struct virtio_device *vdev, unsigned int index, > > > > > > /* Create the vring */ > > > align = ops->get_vq_align(vdpa); > > > + if (ops->get_vq_num_unchangeable) > > > + may_reduce_num = !ops->get_vq_num_unchangeable(vdpa); > > > vq = vring_create_virtqueue(index, num, align, vdev, > > > - true, true, ctx, > > > + true, may_reduce_num, ctx, > > > virtio_vdpa_notify, callback, name); > > > if (!vq) { > > > err = -ENOMEM; > > > diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h > > > index 35648c11e312..f809b7ada00d 100644 > > > --- a/include/linux/vdpa.h > > > +++ b/include/linux/vdpa.h > > > @@ -195,6 +195,9 @@ struct vdpa_iova_range { > > > * @vdev: vdpa device > > > * Returns the iova range supported by > > > * the device. > > > + * @get_vq_num_unchangeable Check if size of virtqueue is unchangeable (optional) > > > + * @vdev: vdpa device > > > + * Returns boolean: unchangeable (true) or not (false) > > > * @set_map: Set device memory mapping (optional) > > > * Needed for device that using device > > > * specific DMA translation (on-chip IOMMU) > > > @@ -262,6 +265,7 @@ struct vdpa_config_ops { > > > const void *buf, unsigned int len); > > > u32 (*get_generation)(struct vdpa_device *vdev); > > > struct vdpa_iova_range (*get_iova_range)(struct vdpa_device *vdev); > > > + bool (*get_vq_num_unchangeable)(struct vdpa_device *vdev); > > > > > > /* DMA ops */ > > > int (*set_map)(struct vdpa_device *vdev, struct vhost_iotlb *iotlb); > > > diff --git a/include/uapi/linux/vhost.h b/include/uapi/linux/vhost.h > > > index c998860d7bbc..184f1f7f8498 100644 > > > --- a/include/uapi/linux/vhost.h > > > +++ b/include/uapi/linux/vhost.h > > > @@ -150,4 +150,6 @@ > > > /* Get the valid iova range */ > > > #define VHOST_VDPA_GET_IOVA_RANGE _IOR(VHOST_VIRTIO, 0x78, \ > > > struct vhost_vdpa_iova_range) > > > +/* Check if the vring size can be change */ > > > +#define VHOST_VDPA_GET_VRING_NUM_UNCHANGEABLE _IOR(VHOST_VIRTIO, 0X79, bool) > > > #endif > > > -- > > > 2.31.1 > > > >