[PATCH] qemu_hotplug: Deny changing @rss and @rss_hash_report attributes of virtio vNICs

[Laine Stump]

On 5/23/22 11:22 AM, Michal Privoznik wrote:
> We have virDomainUpdateDeviceFlags() API that allows changing of
> some attributes of a device whilst domain is still running (e.g.
> setting different QoS, link state change on vNICs). But only very
> limited set of attributes can be changed and we have to check
> whether user isn't trying to sneak in a change that's not
> allowed. Well, in case of a virtio vNIC we forgot to check for
> @rss and @rss_hash_report attributes of <driver/>.
> 
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=2082540
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
>   src/qemu/qemu_hotplug.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)

Reviewed-by: Laine Stump <laine at redhat.com>

(too bad there's not an elegant automated way of pointing out when a new 
field is added that can't be updated at runtime)

> 
> diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
> index 24df66cc9f..f795568299 100644
> --- a/src/qemu/qemu_hotplug.c
> +++ b/src/qemu/qemu_hotplug.c
> @@ -3662,7 +3662,9 @@ qemuDomainChangeNet(virQEMUDriver *driver,
>            olddev->driver.virtio.guest.tso4 != newdev->driver.virtio.guest.tso4 ||
>            olddev->driver.virtio.guest.tso6 != newdev->driver.virtio.guest.tso6 ||
>            olddev->driver.virtio.guest.ecn != newdev->driver.virtio.guest.ecn ||
> -         olddev->driver.virtio.guest.ufo != newdev->driver.virtio.guest.ufo)) {
> +         olddev->driver.virtio.guest.ufo != newdev->driver.virtio.guest.ufo ||
> +         olddev->driver.virtio.rss != newdev->driver.virtio.rss ||
> +         olddev->driver.virtio.rss_hash_report != newdev->driver.virtio.rss_hash_report)) {
>           virReportError(VIR_ERR_OPERATION_UNSUPPORTED, "%s",
>                          _("cannot modify virtio network device driver attributes"));
>           goto cleanup;