[libvirt] [PATCH] netdev: assure that SRIOV PF is online before modifying VF params

[Michal Privoznik]

On 14.05.2015 21:38, Laine Stump wrote:
> The kernel won't complain if you set the mac address and vlan tag for
> an SRIOV VF via its PF, and it will even let you assign the PF to a
> guest using PCI device assignment or macvtap passthrough. But if the
> PF isn't online, the device won't be usable in the guest. This patch
> makes sure that it is turned on.
> 
> Since multiple guests/VFs could use the same PF, there is no point in
> ever setting the PF *off*line.
> 
> This resolves: https://bugzilla.redhat.com/show_bug.cgi?id=893738
> 
> Originally filed against RHEL6, but present in every version of
> libvirt until today.
> ---
>  src/util/virnetdev.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/src/util/virnetdev.c b/src/util/virnetdev.c
> index e14b401..7022dfa 100644
> --- a/src/util/virnetdev.c
> +++ b/src/util/virnetdev.c
> @@ -2258,6 +2258,17 @@ virNetDevReplaceVfConfig(const char *pflinkdev, int vf,
>      char macstr[VIR_MAC_STRING_BUFLEN];
>      char *fileData = NULL;
>      int ifindex = -1;
> +    bool pfIsOnline;
> +
> +    /* Assure that PF is online prior to twiddling with the VF.  It
> +     * *should* be, but if the PF isn't online the changes made to the
> +     * VF via the PF won't take effect, yet there will be no error
> +     * reported.
> +     */
> +    if (virNetDevGetOnline(pflinkdev, &pfIsOnline) < 0)
> +        return ret;
> +    if (!pfIsOnline && virNetDevSetOnline(pflinkdev, true) < 0)
> +        return ret;
>  
>      if (virNetDevGetVfConfig(pflinkdev, vf, &oldmac, &oldvlanid) < 0)
>          goto cleanup;
> 

ACK. Should we set the device back to its previous state if something
goes wrong later in the function?

Michal