Re: [Qemu-devel] [RFC PATCH] vfio: VFIO Driver core framework

[Bhushan Bharat-R65777]

> -----Original Message-----
> From: Wood Scott-B07421
> Sent: Friday, December 02, 2011 11:57 PM
> To: Bhushan Bharat-R65777
> Cc: Stuart Yoder; Alex Williamson; Alexey Kardashevskiy;
> address@hidden; address@hidden; address@hidden; qemu-
> address@hidden; address@hidden; address@hidden;
> address@hidden; address@hidden; address@hidden; Yoder Stuart-B08248;
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> address@hidden; Wood Scott-B07421; address@hidden
> Subject: Re: [Qemu-devel] [RFC PATCH] vfio: VFIO Driver core framework
> 
> On 12/02/2011 12:11 PM, Bhushan Bharat-R65777 wrote:
> > How do we determine whether guest is ready or not? There can be
> multiple device get ready at different time.
> 
> The guest makes a hypercall with a device handle -- at least that's how
> we do it in Topaz.
> 
> > Further if guest have given the device to it user level process or its
> guest. Should not there be some mechanism for a guest to enable/disable
> on per device or group?
> 
> Yes, the same mechanism can be used for that -- though in that case we'll
> also want the ability for the guest to be able to control another layer
> of mapping (which will get quite tricky with PAMU's limitations).
>  This isn't really VFIO's concern, though (unless you're talking about
> the VFIO implementation in the guest).

Scott, I am not sure if there is any real use case where device needed to 
assigned beyond 2 level (host + immediate guest) in nested virtualization.

But if there any exists then will not it be better to virtualizes the iommu 
(PAMU for Freescale)?

Thanks
-Bharat