Re: [Qemu-devel] [Intel-gfx] [Announcement] 2015-Q3 release of XenGT - a Mediated Graphics Passthrough Solution from Intel

[Jike Song <jike.song@intel.com>]

On 11/19/2015 11:52 PM, Alex Williamson wrote:
> On Thu, 2015-11-19 at 15:32 +0000, Stefano Stabellini wrote:
>> On Thu, 19 Nov 2015, Jike Song wrote:
>>> Hi Alex, thanks for the discussion.
>>>
>>> In addition to Kevin's replies, I have a high-level question: can VFIO
>>> be used by QEMU for both KVM and Xen?
>>
>> No. VFIO cannot be used with Xen today. When running on Xen, the IOMMU
>> is owned by Xen.
>
> Right, but in this case we're talking about device MMUs, which are owned
> by the device driver which I think is running in dom0, right?  This
> proposal doesn't require support of the system IOMMU, the dom0 driver
> maps IOVA translations just as it would for itself.  We're largely
> proposing use of the VFIO API to provide a common interface to expose a
> PCI(e) device to QEMU, but what happens in the vGPU vendor device and
> IOMMU backends is specific to the device and perhaps even specific to
> the hypervisor.  Thanks,

Let me conclude this, and please correct me in case of any misread: the
vGPU interface between kernel and QEMU will be through VFIO, with a new
VFIO backend (instead of the existing type1), for both KVMGT and XenGT?


>
> Alex
>

--
Thanks,
Jike