Re: [Qemu-devel] [RFC v9 14/18] vfio: improve vfio_pci_hot_reset to support more case

[Alex Williamson <alex.williamson@redhat.com>]

On Tue, 2015-06-16 at 16:10 +0800, Chen Fan wrote:
> On 06/10/2015 05:24 AM, Alex Williamson wrote:
> > On Tue, 2015-06-09 at 11:37 +0800, Chen Fan wrote:
> >> the vfio_pci_hot_reset differentiate the single and multi in-used
> >> devices for reset. but sometimes we own the group without any devices,
> >> that also should support hot reset.
> > Nope, did you try it?  It can be done, but the group still needs to be
> > connected to a container for isolation.
> I'm sorry for that. because I have no such host in hand. but I think if
> we can keep connect container for each affected group, we also able
> to use this method to do host bus reset.


All you need is a dual-port card with isolation, which includes all
Intel 1G NICs (igb & e1000e) as of the quirks that are currently in
linux-next to be pushed for v4.2.  Intel 10G NICs are already quirked
upstream.  There are certainly ways to fake isolation for testing as
well.  Thanks,

Alex

> >> Signed-off-by: Chen Fan <chen.fan.fnst@cn.fujitsu.com>
> >> ---
> >>   hw/vfio/pci.c | 11 +++++++++++
> >>   1 file changed, 11 insertions(+)
> >>
> >> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> >> index a4e8658..6507f39 100644
> >> --- a/hw/vfio/pci.c
> >> +++ b/hw/vfio/pci.c
> >> @@ -3398,6 +3398,7 @@ static int vfio_pci_hot_reset(VFIOPCIDevice *vdev, bool single)
> >>           PCIHostDeviceAddress host;
> >>           VFIOPCIDevice *tmp;
> >>           VFIODevice *vbasedev_iter;
> >> +        bool found;
> >>   
> >>           host.domain = devices[i].segment;
> >>           host.bus = devices[i].bus;
> >> @@ -3427,6 +3428,7 @@ static int vfio_pci_hot_reset(VFIOPCIDevice *vdev, bool single)
> >>               goto out;
> >>           }
> >>   
> >> +        found = false;
> >>           /* Prep dependent devices for reset and clear our marker. */
> >>           QLIST_FOREACH(vbasedev_iter, &group->device_list, next) {
> >>               if (vbasedev_iter->type != VFIO_DEVICE_TYPE_PCI) {
> >> @@ -3438,12 +3440,21 @@ static int vfio_pci_hot_reset(VFIOPCIDevice *vdev, bool single)
> >>                       ret = -EINVAL;
> >>                       goto out_single;
> >>                   }
> >> +                found = true;
> >>                   vfio_pci_pre_reset(tmp);
> >>                   tmp->vbasedev.needs_reset = false;
> >>                   multi = true;
> >>                   break;
> >>               }
> >>           }
> >> +
> >> +        /*
> >> +         * If we own the group but does not own the device, we also
> >> +         * should call hot reset with multi.
> >> +         */
> >> +        if (!single && !found) {
> >> +            multi = true;
> >> +        }
> >>       }
> >>   
> >>       if (!single && !multi) {
> >
> >
> >
> >
>