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Re: [PATCH v3 0/10] add failover feature for assigned network devices
From: |
Michael S. Tsirkin |
Subject: |
Re: [PATCH v3 0/10] add failover feature for assigned network devices |
Date: |
Tue, 15 Oct 2019 17:17:44 -0400 |
On Tue, Oct 15, 2019 at 01:03:17PM -0600, Alex Williamson wrote:
> On Fri, 11 Oct 2019 13:20:05 +0200
> Jens Freimann <address@hidden> wrote:
>
> > This is implementing the host side of the net_failover concept
> > (https://www.kernel.org/doc/html/latest/networking/net_failover.html)
> >
> > Changes since v2:
> > * back out of creating failover pair when it is a non-networking
> > vfio-pci device (Alex W)
> > * handle migration state change from within the migration thread. I do a
> > timed wait on a semaphore and then check if all unplugs were
> > succesful. Added a new function to each device that checks the device
> > if the unplug for it has happened. When all devices report the succesful
> > unplug *or* the time/retries is up, continue with the migration or
> > cancel. When not all devices could be unplugged I am cancelling at the
> > moment. It is likely that we can't plug it back at the destination which
> > would result in degraded network performance.
> > * fix a few bugs regarding re-plug on migration source and target
> > * run full set of tests including migration tests
> > * add patch for libqos to tolerate new migration state
> > * squashed patch 1 and 2, added patch 8
> >
> > The general idea is that we have a pair of devices, a vfio-pci and a
> > virtio-net device. Before migration the vfio device is unplugged and data
> > flows to the virtio-net device, on the target side another vfio-pci device
> > is plugged in to take over the data-path. In the guest the net_failover
> > module will pair net devices with the same MAC address.
> >
> > * Patch 1 adds the infrastructure to hide the device for the qbus and qdev
> > APIs
> >
> > * Patch 2 sets a new flag for PCIDevice 'partially_hotplugged' which we
> > use to skip the unrealize code path when doing a unplug of the primary
> > device
> >
> > * Patch 3 sets the pending_deleted_event before triggering the guest
> > unplug request
>
> These only cover pcie hotplug, is this feature somehow dependent on
> pcie? There's also ACPI-based PCI hotplug, SHPC hotplug, and it looks
> like s390 has it's own version (of course) of PCI hotplug. IMO, we
> either need to make an attempt to support this universally or the
> option needs to fail if the hotplug controller doesn't support partial
> removal. Thanks,
>
> Alex
Alex, could you please comment a bit more on vfio patches?
Besides what you point out here, any other issues?
--
MST
- [PATCH v3 09/10] net/virtio: add failover support, (continued)
Re: [PATCH v3 0/10] add failover feature for assigned network devices, Michael S. Tsirkin, 2019/10/11
Re: [PATCH v3 0/10] add failover feature for assigned network devices, no-reply, 2019/10/11
Re: [PATCH v3 0/10] add failover feature for assigned network devices, Alex Williamson, 2019/10/15