On Thu, May 13, 2021 at 2:38 PM Chenbo Xia <chenbo....@intel.com> wrote:
>
> This patch fixes an issue of application crash because of vhost iotlb
> not initialized when virtio has multiqueue enabled.
>
> iotlb messages will be sent when some queues are not enabled. If we
> initialize iotlb in vhost_user_set_vring_num, it could happen that
> iotlb update comes when iotlb pool of disabled queues are not
> initialized.
This makes the problem I reproduced disappear at init, but I noticed
the segfault after restarting testpmd once.
And a little bit after this, my vm crashed.
This is not systematic, so I guess there is some condition with how
the virtio device is initialised in the vm.
One question below.
Bugzilla ID: 703
> Fixes: 968bbc7e2e50 ("vhost: avoid IOTLB mempool allocation while IOMMU
> disabled")
>
Reported-by: Pei Zhang <pezh...@redhat.com>
> Signed-off-by: Chenbo Xia <chenbo....@intel.com>
> ---
> lib/vhost/vhost_user.c | 13 +++++++++----
> 1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
> index 611ff209e3..ae4df8eb69 100644
> --- a/lib/vhost/vhost_user.c
> +++ b/lib/vhost/vhost_user.c
> @@ -311,6 +311,7 @@ vhost_user_set_features(struct virtio_net **pdev, struct
> VhostUserMsg *msg,
> uint64_t features = msg->payload.u64;
> uint64_t vhost_features = 0;
> struct rte_vdpa_device *vdpa_dev;
> + uint32_t i;
>
> if (validate_msg_fds(msg, 0) != 0)
> return RTE_VHOST_MSG_RESULT_ERR;
> @@ -389,6 +390,14 @@ vhost_user_set_features(struct virtio_net **pdev, struct
> VhostUserMsg *msg,
> vdpa_dev->ops->set_features(dev->vid);
>
> dev->flags &= ~VIRTIO_DEV_FEATURES_FAILED;
> +
> + if (dev->features & (1ULL << VIRTIO_F_IOMMU_PLATFORM)) {
> + for (i = 0; i < dev->nr_vring; i++) {
I don't know the vhost-user protocol.
At this point of the device init/life, are we sure nr_vring is set to
the max number of vring?
The logs I have tend to say it is the case, but is there a guarantee
in the protocol?
Another way to fix would be to allocate on the first
VHOST_USER_IOTLB_MSG message received for a vring.
> + if (vhost_user_iotlb_init(dev, i))
> + return RTE_VHOST_MSG_RESULT_ERR;
> + }
> + }
> +
> return RTE_VHOST_MSG_RESULT_OK;
> }
>
--
David Marchand
