On 2017年05月31日 23:32, Maxime Coquelin wrote:
[0]:https://gitlab.com/mcoquelin/dpdk-next-virtio/commits/vhost_iotlb_proto_v2
[1]:https://lists.gnu.org/archive/html/qemu-devel/2016-04/msg00095.html
Overall, this looks good to me. I do think patch 3 isn't a good idea
though, if slave wants something let it request it.
Need to find out why does vhost in kernel want the used ring iotlb at
start time - especially considering we aren't even guaranteed one entry
covers the whole ring, and invalidates should affect all addresses at
least in theory.
The reason is probably we want to verify whether or not we could
correctly access used ring in vhost_vq_init_access(). It was there
since vhost_net is introduced. We can think to remove this limitation
maybe.
Even if we remove the limitation on Kernel side, we will still have to
keep this workaround for compatibility with older kernels. Having done
the test, I can confirm it is currently necessary.
Thanks,
Maxime
Right, it was probably too late for the change.