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

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

On Wed, 2015-06-17 at 14:28 +0800, Chen Fan wrote:
> On 06/16/2015 10:08 PM, Alex Williamson wrote:
> > 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,
> 
> I just have a Intel Corporation 82576 dual-port card, but how can I fake
> isolation group for this card in linux-next kernel? can you tell me the
> document link?

If you're running linux-next and have the card installed under a root
port that provides isolation then each port should be in a separate
iommu group.  Nearly all Intel PCH root ports should have quirks to
enable isolation.  If you're installing it in a processor root port
slot, you need to use a Xeon E5 or better CPU or else the lack of
isolation at the root port will negate the isolation capabilities of the
endpoint.  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) {
> >>>
> >>>
> >>>
> >
> >
> >
> > .
> >
>