[PATCH 3/3] net/vhost: fix Rx interrupt

[David Marchand]

On Thu, Mar 9, 2023 at 1:38 PM David Marchand <david.marchand at redhat.com> wrote:
>
> In the situation when a port was started while no virtio driver was
> connected, Rx interrupts were broken.
> They were also broken after a virtio driver reconnects.
>
> There were several issues mixed in:
> - this driver was not exposing a fixed file descriptor per Rx queue,
>   If a virtio driver was not connected yet, each Rx queue vector was
>   pointing at a -1 fd, and an application could interpret this as a lack
>   of Rx interrupt support,
> - when a virtio driver later (re)connected, this net/vhost driver was
>   hacking into the EAL layer epoll fd to remove a old vring kickfd and
>   insert the new vring kickfd. This hack constitutes a layer violation
>   plus users of rte_eth_dev_rx_intr_ctl_q_get_fd() were not notified of
>   this change,
> - in the case of reconnection, because the interrupt handle was
>   reallocated, a 0 fd was failing to be removed from the EAL layer
>   epoll fd, which resulted in never fixing the EAL epoll fd,
>
> To fix Rx interrupts:
> - allocating (eth_vhost_install_intr) / releasing
>   (eth_vhost_uninstall_intr) the interrupt handle is moved when
>   starting / closing the port, while setting / resetting per rxq fd is
>   triggered by vhost events via some new helpers (see
>   eth_vhost_configure_intr and eth_vhost_unconfigure_intr),
> - a "proxy" epoll fd is created per Rx queue at the time the interrupt
>   handle is allocated, so applications can start waiting for events on
>   those fds, even before a virtio driver initialises,
> - when available, vring kickd are populated in the "proxy" epoll fd,
>

Maxime, Chenbo,

Dukai confirms this series fix it, we can mark this patch as fixing:
Bugzilla ID: 1135

Do you want me to respin a series or can you fix when applying?


> Fixes: 3f8ff12821e4 ("vhost: support interrupt mode")
> Fixes: 3d4cd4be577c ("net/vhost: fix interrupt mode")
> Fixes: d61138d4f0e2 ("drivers: remove direct access to interrupt handle")
> Cc: stable at dpdk.org
>
> Signed-off-by: David Marchand <david.marchand at redhat.com>

Thanks.


-- 
David Marchand