Re: [PATCH QEMU HCI-8.1 v5 30/36] VZ: migration/cpr-exec: take the vhost-net devices back if exec fails

[no-reply@sashiko.virtuozzo.com]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] vhost-net: missing vhost_net_cpr_set_owners() stub breaks link without vhost-net
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commit 254c845f4346569ec4ac6196d59e129392d054ac
Author: Andrey Drobyshev <andrey.drobyshev@virtuozzo.com>

VZ: migration/cpr-exec: take the vhost-net devices back if exec fails

This patch adds vhost_net_cpr_set_owners(), which calls VHOST_SET_OWNER
again and re-registers the vring call and err fds for vhost-net devices
that were released before execve(). It is called from the fail path in
cpr_exec_cb() when exec fails. A new cpr_owner_reset flag in struct
vhost_net records which devices were actually released.

> diff --git a/migration/cpr-exec.c b/migration/cpr-exec.c
> index df11b0c7633cb..e4ea160698cd4 100644
> --- a/migration/cpr-exec.c
> +++ b/migration/cpr-exec.c
> @@ -253,6 +253,8 @@ fail:
>      if (cpr_ram_rdonly) {
>          cpr_ram_restore_rw();
>      }
> +    /* Still the same mm, take back the vhost-net devices we released */
> +    vhost_net_cpr_set_owners();
>  
>      /* Note, we can go from state COMPLETED to FAILED */
>      migration_call_notifiers(MIG_EVENT_PRECOPY_FAILED, NULL);

[Severity: Low]
Will this link in configurations that build hw/net/vhost_net-stub.c
instead of hw/net/vhost_net.c?

cpr_exec_cb() in migration/cpr-exec.c is built unconditionally. It now
calls vhost_net_cpr_set_owners() right after the existing call to
vhost_net_cpr_reset_owners().

hw/net/meson.build builds vhost_net.c only when vhost-net and
CONFIG_VIRTIO_NET are enabled:

system_ss.add(when: 'CONFIG_VIRTIO_NET', if_true: files('vhost_net.c'), if_false: files('vhost_net-stub.c'))

Other configurations get vhost_net-stub.c. Examples are
--disable-vhost-net, non-Linux hosts, and builds without VIRTIO_NET.
That file ends after vhost_net_save_acked_features() and defines neither
vhost_net_cpr_reset_owners() nor vhost_net_cpr_set_owners().

I found both functions only in hw/net/vhost_net.c and
include/net/vhost_net.h, including at the end of the series. This patch
therefore adds a second undefined reference in stub builds. The missing
stub for vhost_net_cpr_reset_owners() was already there before this
patch.

Could stubs for both functions be added to vhost_net-stub.c?

-- 
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261023-vfio_v1-v5-0-ba0bf3c6d122@virtuozzo.com?part=30