[Intel-wired-lan] [PATCH V2] ixgbe: Allow disabling VFs when they are pre-existing

[Duyck, Alexander H <alexander.h.duyck@intel.com>]

On Fri, 2017-03-31 at 17:26 -0700, Mark D Rustad wrote:
> Right now if VFs existing when the driver is loaded, it is not
> possible to destroy those VFs, even though messages from the driver
> suggest doing that when trying to change the number. This change
> permits the disabling of SR-IOV for the case when there are
> pre-existing VFs.
> 
> Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
> ---
> Changes in V2:
> - Remove unwanted content in the changelog message - sorry about that
> ---
>  src/CORE/ixgbe_sriov.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/CORE/ixgbe_sriov.c b/src/CORE/ixgbe_sriov.c
> index 9b7d05110fe9..231acf274a70 100644
> --- a/src/CORE/ixgbe_sriov.c
> +++ b/src/CORE/ixgbe_sriov.c
> @@ -603,7 +603,7 @@ static int ixgbe_pci_sriov_disable(struct pci_dev *dev)
>  	u32 current_flags = adapter->flags;
>  #endif
>  
> -	if (adapter->num_vfs == 0)
> +	if (!adapter->num_vfs && !pci_num_vf(dev))
>  		return -EINVAL;
>  
>  	err = ixgbe_disable_sriov(adapter);

So I assume this patch isn't meant for upstream at all since there
isn't a CORE folder in the upstream kernel. Also this patch does't
apply to any existing upstream tree.

On a side note it would probably be best to just drop this check
entirely. Checking for adapter->num_vfs doesn't tell you anything other
than the fact that memory is allocated for vfinfo.

In the upstream driver one thing we should probably do is add a check
against pci_num_vf() in ixgbe_disable_sriov instead of using
"!(adapter->flags & IXGBE_FLAG_SRIOV_ENABLED)". That way we will try to
disable SR-IOV if that is what we are actually trying to do instead of
only if the driver had allocated memory for it.

However like I stated on the other patch it would probably be best to
take a look at fm10k and borrow from that since I think what we really
should be doing is attempting to resume with the same number of VFs
that were previously enabled so the VFs can resume operation if the PF
is reloaded with support for SR-IOV.

- Alex