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Date: Wed, 27 Jan 2016 08:06:13 +0800
From: Jike Song <jike.song@intel.com>
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Subject: Re: [Qemu-devel] VFIO based vGPU(was Re: [Announcement] 2015-Q3
 release of XenGT - a Mediated ...)
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To: Yang Zhang <yang.zhang.wz@gmail.com>
Cc: "Ruan, Shuai" <shuai.ruan@intel.com>, "Tian, Kevin" <kevin.tian@intel.com>, Neo Jia <cjia@nvidia.com>, "kvm@vger.kernel.org" <kvm@vger.kernel.org>, "igvt-g@lists.01.org" <igvt-g@ml01.01.org>, qemu-devel <qemu-devel@nongnu.org>, Alex Williamson <alex.williamson@redhat.com>, "Lv,
	Zhiyuan" <zhiyuan.lv@intel.com>, Paolo Bonzini <pbonzini@redhat.com>, Gerd Hoffmann <kraxel@redhat.com>

On 01/26/2016 10:05 PM, Yang Zhang wrote:
> On 2016/1/26 15:41, Jike Song wrote:
>
>> We will need to extend:
>>
>> 	- VFIO_DEVICE_GET_REGION_INFO
>>
>>
>> a) adding a flag: DONT_MAP. For example, the MMIO of vgpu
>> should be trapped instead of being mmap-ed.
> 
> I may not in the context, but i am curious how to handle the DONT_MAP in 
> vfio driver? Since there are no real MMIO maps into the region and i 
> suppose the access to the region should be handled by vgpu in i915 
> driver, but currently most of the mmio accesses are handled by Qemu.
>

Hi Yang,

MMIO accesses are supposed to be handled in kernel, without vm-exiting
to QEMU, similar to in-kernel irqchip :)

--
Thanks,
Jike