[RFC PATCH v2 0/3] drm/i915/gvt: Enable vGPU local display direct flip

[Gerd Hoffmann]

  Hi,

> > When running on a drm-lease that would be a bit rude.  Also I don't think
> > logind will hand out input file handles in that case.  In case there are
> > dedicated input devices for the guest you can use input-linux or usb pass-
> > through.  If not, then, hmm, no idea.

> We see more and more people would like to use gvt-g to build the
> intelligent desktop virtualization (IDV) products, where 3 VMs are
> running with each one having a dedicated monitor, a set of USB
> keyboard/mouse and one audio card. Since the inputs problem can be
> solved by passing through the input devices, the most challenge work
> is how to assign the monitors.

Well, yes, that'll work fine.  With dedicated input devices
usb-passthrough will do the trick.

For that use case having drm-lease support in systemd-logind would
make alot of sense.  logind already has multiseat support, but only with
different display devices.  With drm leases it should be possible to
extend that to also cover different monitors on a single display device.

> And another work, as we discussed, can improve the user experience is
> to deliver the page flip to user space where qemu ui could leverage to
> call the ui refresh. 

> Here is the RFC version: https://github.com/intel/gvt-linux/commit/9eb50f032d3ebea8d8bfa62e0546dbb8af3b84d9
> Can you share your comments about it?

I would name the ioctl VFIO_DEVICE_SET_GFX_FLIP_EVENTFD.  Also I think
we don't need a separate probe call.  Userspace can just try to setup
the eventfd and fallback to timer polling in case it fails.
Documentation should be more verbose too.  Othwerwise it looks fine to
me, I'd suggest to send the vfio header patch to the vfio list for
review.

cheers,
  Gerd