Re: [dpdk-dev] [PATCH v3] vhost: fix vhost user virtqueue not accessible

["Liu, Yong" <yong.liu@intel.com>]

> -----Original Message-----
> From: Bie, Tiwei
> Sent: Thursday, October 31, 2019 6:42 PM
> To: Liu, Yong <yong.liu@intel.com>
> Cc: maxime.coquelin@redhat.com; Wang, Zhihong <zhihong.wang@intel.com>;
> amorenoz@redhat.com; dev@dpdk.org
> Subject: Re: [PATCH v3] vhost: fix vhost user virtqueue not accessible
> 
> On Wed, Oct 30, 2019 at 10:56:02PM +0800, Marvin Liu wrote:
> > Log feature is disabled in vhost user, so that log address was invalid
> > when checking. Check whether log address is valid can workaround it.
> > Also log address should be translated in packed ring virtqueue.
> >
> > Fixes: 04cfc7fdbfca ("vhost: translate incoming log address to gpa")
> >
> > Signed-off-by: Marvin Liu <yong.liu@intel.com>
> > ---
> >  lib/librte_vhost/vhost_user.c | 30 +++++++++++++-----------------
> >  1 file changed, 13 insertions(+), 17 deletions(-)
> >
> > diff --git a/lib/librte_vhost/vhost_user.c
> b/lib/librte_vhost/vhost_user.c
> > index 61ef699ac..7754d2467 100644
> > --- a/lib/librte_vhost/vhost_user.c
> > +++ b/lib/librte_vhost/vhost_user.c
> > @@ -641,11 +641,23 @@ translate_ring_addresses(struct virtio_net *dev,
> int vq_index)
> >  	struct vhost_vring_addr *addr = &vq->ring_addrs;
> >  	uint64_t len, expected_len;
> >
> > +	dev = numa_realloc(dev, vq_index);
> 
> We need to update `vq->desc` first before doing numa_realloc.
> https://github.com/DPDK/dpdk/blob/19397c7bf2545e6adab41b657a1f1da3c7344e7b/
> lib/librte_vhost/vhost_user.c#L445
> 
> > +	vq = dev->virtqueue[vq_index];
> > +	if (addr->flags & (1 << VHOST_VRING_F_LOG)) {
> 
> `vq` can be reallocated by numa_realloc.
> We need to update the `addr` pointer before using it.
> 

Hi Tiwei,
Numa_realloc function will copy data from original vq structure to new vq when reallocating.
The content of vhost_ring_addr will be the same in new and old vqs, it may not be necessary to update pointer.

Regards,
Marvin

> Thanks,
> Tiwei
> 
> 
> > +		vq->log_guest_addr =
> > +			translate_log_addr(dev, vq, addr->log_guest_addr);
> > +		if (vq->log_guest_addr == 0) {
> > +			RTE_LOG(DEBUG, VHOST_CONFIG,
> > +					"(%d) failed to map log_guest_addr.\n",
> > +					dev->vid);
> > +			return dev;
> > +		}
> > +	}
> > +
> >  	if (vq_is_packed(dev)) {
> >  		len = sizeof(struct vring_packed_desc) * vq->size;
> >  		vq->desc_packed = (struct vring_packed_desc *)(uintptr_t)
> >  			ring_addr_to_vva(dev, vq, addr->desc_user_addr, &len);
> > -		vq->log_guest_addr = 0;
> >  		if (vq->desc_packed == NULL ||
> >  				len != sizeof(struct vring_packed_desc) *
> >  				vq->size) {
> > @@ -655,10 +667,6 @@ translate_ring_addresses(struct virtio_net *dev, int
> vq_index)
> >  			return dev;
> >  		}
> >
> > -		dev = numa_realloc(dev, vq_index);
> > -		vq = dev->virtqueue[vq_index];
> > -		addr = &vq->ring_addrs;
> > -
> >  		len = sizeof(struct vring_packed_desc_event);
> >  		vq->driver_event = (struct vring_packed_desc_event *)
> >  					(uintptr_t)ring_addr_to_vva(dev,
> > @@ -701,10 +709,6 @@ translate_ring_addresses(struct virtio_net *dev, int
> vq_index)
> >  		return dev;
> >  	}
> >
> > -	dev = numa_realloc(dev, vq_index);
> > -	vq = dev->virtqueue[vq_index];
> > -	addr = &vq->ring_addrs;
> > -
> >  	len = sizeof(struct vring_avail) + sizeof(uint16_t) * vq->size;
> >  	if (dev->features & (1ULL << VIRTIO_RING_F_EVENT_IDX))
> >  		len += sizeof(uint16_t);
> > @@ -741,14 +745,6 @@ translate_ring_addresses(struct virtio_net *dev, int
> vq_index)
> >  		vq->last_avail_idx = vq->used->idx;
> >  	}
> >
> > -	vq->log_guest_addr =
> > -		translate_log_addr(dev, vq, addr->log_guest_addr);
> > -	if (vq->log_guest_addr == 0) {
> > -		RTE_LOG(DEBUG, VHOST_CONFIG,
> > -			"(%d) failed to map log_guest_addr .\n",
> > -			dev->vid);
> > -		return dev;
> > -	}
> >  	vq->access_ok = 1;
> >
> >  	VHOST_LOG_DEBUG(VHOST_CONFIG, "(%d) mapped address desc: %p\n",
> > --
> > 2.17.1
> >