On Mon, Aug 17, 2026, 16:59 Connor Kite <[email protected]> wrote:
> On Sun, Aug 9, 2026 at 5:46 AM Stefan Hajnoczi <[email protected]> wrote: > > > > On Sat, Aug 8, 2026 at 11:32 AM Connor Kite <[email protected]> > wrote: > > > > > > iova-tree expects inclusive range sizing when maps are allocated or > searched. > > > Currently, svqs use exclusive sizing when searching their > > > vhost-iova-tree for a match to the region to be translated. This could > > > lead to errors if the region to be translated is at the edge of an iova > > > region. > > > > > > Fix this by reducing `needle.size` by 1 in > > > vhost_svq_translate_addr to bring it in line with DMAMap and iova-tree > > > convention. > > > > > > This patch is an updated version of one from the patch series > "vhost-user: > > > isolated memory". The patch has been isolated from the series as it > > > is not tightly coupled with the rest of the series. > > > > > > Signed-off-by: Connor Kite <[email protected]> > > > --- > > > hw/virtio/vhost-shadow-virtqueue.c | 10 ++++++++-- > > > 1 file changed, 8 insertions(+), 2 deletions(-) > > > > > > diff --git a/hw/virtio/vhost-shadow-virtqueue.c > b/hw/virtio/vhost-shadow-virtqueue.c > > > index bcb7f2ffc7..c8831d52be 100644 > > > --- a/hw/virtio/vhost-shadow-virtqueue.c > > > +++ b/hw/virtio/vhost-shadow-virtqueue.c > > > @@ -99,19 +99,25 @@ static bool vhost_svq_translate_addr(const > VhostShadowVirtqueue *svq, > > > const DMAMap *map; > > > DMAMap needle; > > > > > > + if (unlikely(iovec[i].iov_len == 0)) { > > > + qemu_log_mask(LOG_GUEST_ERROR, > > > + "Zero-sized buffer made available by > guest"); > > > + return false; > > > + } > > > + > > > /* Check if the descriptor is backed by guest memory */ > > > if (gpas) { > > > /* Search the GPA->IOVA tree */ > > > needle = (DMAMap) { > > > .translated_addr = gpas[i], > > > - .size = iovec[i].iov_len, > > > + .size = iovec[i].iov_len - 1, /* Inclusive */ > > > }; > > > map = vhost_iova_tree_find_gpa(svq->iova_tree, &needle); > > > } else { > > > /* Search the IOVA->HVA tree */ > > > needle = (DMAMap) { > > > .translated_addr = > (hwaddr)(uintptr_t)iovec[i].iov_base, > > > - .size = iovec[i].iov_len, > > > + .size = iovec[i].iov_len - 1, /* Inclusive */ > > > }; > > > map = vhost_iova_tree_find_iova(svq->iova_tree, &needle); > > > } > > > > It looks suspicious that only the vhost_iova_tree_find_gpa() calls are > > modified, so I checked to see if other users of svq->iova_tree treat > > .size as inclusive or exclusive. There is only one user, > > hw/virtio/vhost-vdpa.c, and it treats .size as inclusive. This is not > > obvious from the patch, but it does indeed make everything consistent. > > (It would be helpful to include this kind of context in the commit > > message in the future.) > > > > Reviewed-by: Stefan Hajnoczi <[email protected]> > > Resending a message that was accidentally sent just to Stefan: > > Yes, I think you will recall that I was also confused about the use of > inclusive sizes in iova-tree, and exclusive sizes virtually everywhere > else that does not touch iova-tree. > > For clarity, is it worth making a REV2 of this patch with an updated > message? > It would be nice if you could do that. Thanks! Stefan >
