Message-ID: <1447948366.4697.119.camel@redhat.com>
Subject: Re: [Intel-gfx] [Announcement] 2015-Q3 release of XenGT - a
 Mediated Graphics Passthrough Solution from Intel
From: Alex Williamson <alex.williamson@redhat.com>
To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Jike Song <jike.song@intel.com>, "Tian, Kevin" <kevin.tian@intel.com>,
        "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>,
        "igvt-g@ml01.01.org" <igvt-g@ml01.01.org>,
        "intel-gfx@lists.freedesktop.org" <intel-gfx@lists.freedesktop.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "White, Michael L" <michael.l.white@intel.com>,
        "Dong, Eddie" <eddie.dong@intel.com>, "Li, Susie" <susie.li@intel.com>,
        "Cowperthwaite, David J" <david.j.cowperthwaite@intel.com>,
        "Reddy, Raghuveer" <raghuveer.reddy@intel.com>,
        "Zhu, Libo" <libo.zhu@intel.com>, "Zhou, Chao" <chao.zhou@intel.com>,
        "Wang, Hongbo" <hongbo.wang@intel.com>,
        "Lv, Zhiyuan" <zhiyuan.lv@intel.com>,
        qemu-devel <qemu-devel@nongnu.org>,
        Paolo Bonzini <pbonzini@redhat.com>, Gerd Hoffmann <kraxel@redhat.com>
Date: Thu, 19 Nov 2015 08:52:46 -0700
In-Reply-To: <alpine.DEB.2.02.1511191529370.1107@kaball.uk.xensource.com>
References: <53D215D3.50608@intel.com> <547FCAAD.2060406@intel.com>
	 <54AF967B.3060503@intel.com> <5527CEC4.9080700@intel.com>
	 <559B3E38.1080707@intel.com> <562F4311.9@intel.com>
	 <1447870341.4697.92.camel@redhat.com>
	 <AADFC41AFE54684AB9EE6CBC0274A5D15F7152DB@SHSMSX101.ccr.corp.intel.com>
	 <564D78D0.80904@intel.com>
	 <alpine.DEB.2.02.1511191529370.1107@kaball.uk.xensource.com>
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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,

Alex

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