On Mon, Apr 06, 2026 at 23:15:32 -0400, Laine Stump via Devel wrote:
> From: Laine Stump <[email protected]>
>
> When support for vhostuser devices was added, it was just
> blanket-prevented from making any changes to a live device with
> update-device. This is problematic because the link state of a network
> device is modified with update-device. Most all of the parameters of a
> vhostuser network device are individually checked within
> qemuDomainChangeNet() anyway, so we don't need to just do a BRS (Big
> Red Switch) forbidding of any change. We do need to check for
> modifications to the socket parameters (path, type, reconnect) though,
> since those are vhostuser-specific (we're not already checking for
> them elsewhere) and they can't be changed on a live interface.
>
> Resolves https://redhat.atlassian.net/browse/RHEL-152533
> Resolves: https://bugs.passt.top/show_bug.cgi?id=198
> Signed-off-by: Laine Stump <[email protected]>
> ---
> src/qemu/qemu_hotplug.c | 18 ++++++++++++++++++
> 1 file changed, 18 insertions(+)
>
> diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
> index 7ab28bed6d..e33ef5e1e9 100644
> --- a/src/qemu/qemu_hotplug.c
> +++ b/src/qemu/qemu_hotplug.c
> @@ -4129,6 +4129,24 @@ qemuDomainChangeNet(virQEMUDriver *driver,
> break;
>
> case VIR_DOMAIN_NET_TYPE_VHOSTUSER:
> + /* the path the to vhostuser socket and its parameters
> + * can't be changed. In the case of a PASST backend using
> + * vhostuser, all of those parameters are internally
> + * generated anyway, so the user wouldn't be able to
> + * specify them in the updated XML.
> + */
While the comment explains it, the condition is a bit unpleasant to
read.
I'd suggest doing:
if (newdev->backend.type == VIR_DOMAIN_NET_BACKEND_PASST)
break;
first with the comment stating that the passt stuff is autogenerated and
then follow up ...
> + if (newdev->backend.type != VIR_DOMAIN_NET_BACKEND_PASST &&
... with the rest of this as another condition:
> + (STRNEQ_NULLABLE(olddev->data.vhostuser->data.nix.path,
> newdev->data.vhostuser->data.nix.path) ||
> + olddev->data.vhostuser->data.nix.listen !=
> newdev->data.vhostuser->data.nix.listen ||
> + olddev->data.vhostuser->data.nix.reconnect.enabled !=
> newdev->data.vhostuser->data.nix.reconnect.enabled ||
> + olddev->data.vhostuser->data.nix.reconnect.timeout !=
> newdev->data.vhostuser->data.nix.reconnect.timeout)) {
> + virReportError(VIR_ERR_OPERATION_UNSUPPORTED,
> + _("unable to change socket config on '%1$s'
> network type"),
> + virDomainNetTypeToString(newdev->type));
> + goto cleanup;
> + }
> + break;
> +
> case VIR_DOMAIN_NET_TYPE_HOSTDEV:
> case VIR_DOMAIN_NET_TYPE_VDPA:
> case VIR_DOMAIN_NET_TYPE_NULL:
Reviewed-by: Peter Krempa <[email protected]>
