Re: [PATCH V2 9/9] vhost: do not return -EAGIAN for non blocking invalidation too early

[Jason Wang <jasowang@xxxxxxxxxx>]

On 2019/7/31 下午5:59, Stefano Garzarella wrote:
> A little typo in the title: s/EAGIAN/EAGAIN
>
> Thanks,
> Stefano


Right, will fix if need respin or Michael can help to fix.

Thanks


> On Wed, Jul 31, 2019 at 04:46:55AM -0400, Jason Wang wrote:
> > Instead of returning -EAGAIN unconditionally, we'd better do that only
> > we're sure the range is overlapped with the metadata area.
> >
> > Reported-by: Jason Gunthorpe <jgg@xxxxxxxx>
> > Fixes: 7f466032dc9e ("vhost: access vq metadata through kernel virtual address")
> > Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> > ---
> >   drivers/vhost/vhost.c | 32 +++++++++++++++++++-------------
> >   1 file changed, 19 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
> > index fc2da8a0c671..96c6aeb1871f 100644
> > --- a/drivers/vhost/vhost.c
> > +++ b/drivers/vhost/vhost.c
> > @@ -399,16 +399,19 @@ static void inline vhost_vq_sync_access(struct vhost_virtqueue *vq)
> >   	smp_mb();
> >   }
> >   
> > -static void vhost_invalidate_vq_start(struct vhost_virtqueue *vq,
> > -				      int index,
> > -				      unsigned long start,
> > -				      unsigned long end)
> > +static int vhost_invalidate_vq_start(struct vhost_virtqueue *vq,
> > +				     int index,
> > +				     unsigned long start,
> > +				     unsigned long end,
> > +				     bool blockable)
> >   {
> >   	struct vhost_uaddr *uaddr = &vq->uaddrs[index];
> >   	struct vhost_map *map;
> >   
> >   	if (!vhost_map_range_overlap(uaddr, start, end))
> > -		return;
> > +		return 0;
> > +	else if (!blockable)
> > +		return -EAGAIN;
> >   
> >   	spin_lock(&vq->mmu_lock);
> >   	++vq->invalidate_count;
> > @@ -423,6 +426,8 @@ static void vhost_invalidate_vq_start(struct vhost_virtqueue *vq,
> >   		vhost_set_map_dirty(vq, map, index);
> >   		vhost_map_unprefetch(map);
> >   	}
> > +
> > +	return 0;
> >   }
> >   
> >   static void vhost_invalidate_vq_end(struct vhost_virtqueue *vq,
> > @@ -443,18 +448,19 @@ static int vhost_invalidate_range_start(struct mmu_notifier *mn,
> >   {
> >   	struct vhost_dev *dev = container_of(mn, struct vhost_dev,
> >   					     mmu_notifier);
> > -	int i, j;
> > -
> > -	if (!mmu_notifier_range_blockable(range))
> > -		return -EAGAIN;
> > +	bool blockable = mmu_notifier_range_blockable(range);
> > +	int i, j, ret;
> >   
> >   	for (i = 0; i < dev->nvqs; i++) {
> >   		struct vhost_virtqueue *vq = dev->vqs[i];
> >   
> > -		for (j = 0; j < VHOST_NUM_ADDRS; j++)
> > -			vhost_invalidate_vq_start(vq, j,
> > -						  range->start,
> > -						  range->end);
> > +		for (j = 0; j < VHOST_NUM_ADDRS; j++) {
> > +			ret = vhost_invalidate_vq_start(vq, j,
> > +							range->start,
> > +							range->end, blockable);
> > +			if (ret)
> > +				return ret;
> > +		}
> >   	}
> >   
> >   	return 0;
> > --
> > 2.18.1