[vfio-users] Saving/restoring VFIO VMs

[Quentin Deldycke]

You really think vfio-pci never send commands to the card?

If it is the case, how linux can put this device to sleep? Vfio-pci manage
the card. It just pass command from vm to the card :)

I know, i have ~5 pcie controllers linked to my vm, gpu, nvme disk, usb
controller, audio controller and sata controller.

nvme and sata controller can navigate between linux and windows without
problems, drivers seems pretty stables.
USB controller, and gpu can't be used on linux if they are not "cleanly"
shutted down by windows. (usb controller can't execute commands, and my r9
290 hard freezes)

PCIe reset is really complicated because it work differently on a pcie
device to another.

I tried during a period to dompmsuspend vm then host. And re-start vm at
host wakeup. Sometimes it work, sometimes hard freeze.

Think that this capacity was never tested by AMD and nvidia. Just because
it never happen in real life with 99.99999% of computers.



--
Deldycke Quentin


On 18 April 2017 at 18:13, Patrick O'Callaghan <poc at usb.ve> wrote:

> On Tue, 2017-04-18 at 14:02 +0200, Quentin Deldycke wrote:
> > In your case, another OS (linux) use this card at a moment or another,
> > reset some bus (when re-binded to vfio). The reset of cards is already
> > hardly supported by windows / linux driver.
>
> This is a pass-through device. The whole point is that Linux never
> touches it. If Windows can save/restore its state, that should be
> enough in theory.
>
> poc
>
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