Hi Marvin,
On 10/25/19 6:20 PM, Marvin Liu wrote:
> Log feature is disabled in vhost user, so that log address was invalid
> when checking. Add feature bit check can skip useless address check.
>
Just so I understand, what conditions is the log address invalid?
> Fixes: 04cfc7fdbfca ("vhost: translate incoming log address to gpa")
>
> Signed-off-by: Marvin Liu <yong....@intel.com>
> ---
> lib/librte_vhost/vhost_user.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/lib/librte_vhost/vhost_user.c b/lib/librte_vhost/vhost_user.c
> index 61ef699ac..0407fdc29 100644
> --- a/lib/librte_vhost/vhost_user.c
> +++ b/lib/librte_vhost/vhost_user.c
> @@ -741,13 +741,15 @@ 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;
> + if (dev->features & (1ULL << VHOST_F_LOG_ALL)) {
> + vq->log_guest_addr =
> + translate_log_addr(dev, vq, addr->log_guest_addr);
VHOST_F_LOG_ALL is only negotiated once the migration has started (at least from
qemu's perspective).
That means that we will postponing the translation of the log address to the
vhost_user_set_vring_addr() call that follows the VHOST_F_LOG_ALL enabling. In
that call there are (at least) two things that could go wrong and lead to a
migration failure:
- If VHOST_USER_F_PROTOCOL_FEATURES is not enabled, the address won't be
translated:
vhost_user:795
if ((vq->enabled && (dev->features &
(1ULL << VHOST_USER_F_PROTOCOL_FEATURES))) ||
access_ok) {
dev = translate_ring_addresses(dev, msg->payload.addr.index);
if (!dev)
return RTE_VHOST_MSG_RESULT_ERR;
*pdev = dev;
}
- If the IOMMU is enabled and there's a miss, we would have to wait for the
IOTLB_UPDATE and during that time, there would be failed accesses to the (still
untranslated) log address.
> + 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;
>
>
Thanks,
Adrian
