On Fri, 13 Mar 2015 20:42:03 +1100 Alexey Kardashevskiy <a...@ozlabs.ru> wrote:
> The value returned by virtio_vring_size() is used to allocate memory > for vring. The used descriptor list (array of vring_used_elem) is > counted by the header - vring_used struct - is not. > > This fixes virtio_vring_size() to return the correct size. > At the moment rings are quite small (256) and allocated with > 4096 alignment, this is why we have not been having issues with > this so far. > > Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru> > --- > Changes: > v2: > * remove magic numbers > --- > lib/libvirtio/virtio.c | 6 ++++-- > 1 file changed, 4 insertions(+), 2 deletions(-) > > diff --git a/lib/libvirtio/virtio.c b/lib/libvirtio/virtio.c > index b010796..f9c00a6 100644 > --- a/lib/libvirtio/virtio.c > +++ b/lib/libvirtio/virtio.c > @@ -32,8 +32,10 @@ > */ > unsigned long virtio_vring_size(unsigned int qsize) > { > - return VQ_ALIGN(sizeof(struct vring_desc) * qsize + 2 * (2 + qsize)) > - + VQ_ALIGN(sizeof(struct vring_used_elem) * qsize); > + return VQ_ALIGN(sizeof(struct vring_desc) * qsize + > + sizeof(struct vring_avail) + sizeof(uint16_t) * > qsize) + > + VQ_ALIGN(sizeof(struct vring_used) + > + sizeof(struct vring_used_elem) * qsize); > } Reviewed-by: Thomas Huth <th...@linux.vnet.ibm.com> That should be at least ok for the current status that we support in SLOF. I think I might have written the original version of that function with a very old version of the virtio spec (v0.8.10), when ther was no "used_event" event field in the struct vring_avail defined yet. But if SLOF ever supports VIRTIO_F_EVENT_IDX, we've got to keep in mind to add some additional bytes here, too. Thomas _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev