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Re: [Xen-devel] Notes from PCI Passthrough design discussion at Xen Summit

On Thu, Jul 20, 2017 at 03:02:19PM +0530, Manish Jaggi wrote:
> Hi Roger,
> On 7/20/2017 1:54 PM, Roger Pau Monné wrote:
> > On Thu, Jul 20, 2017 at 09:24:36AM +0530, Manish Jaggi wrote:
> > > Hi Punit,
> > > 
> > > On 7/19/2017 8:11 PM, Punit Agrawal wrote:
> > > > I took some notes for the PCI Passthrough design discussion at Xen
> > > > Summit. Due to the wide range of topics covered, the notes got sparser
> > > > towards the end of the session. I've tried to attribute names against
> > > > comments but have very likely got things mixed up. Apologies in advance.
> > > Was curious if any discussions happened on the RC Emu (config space
> > > emulation) as per slide 18
> > > https://schd.ws/hosted_files/xendeveloperanddesignsummit2017/76/slides.pdf
> > Part of this is already posted on the list (ATM for x86 only) but the
> > PCI specification (and therefore the config space emulation) is not
> > tied to any arch:
> > 
> > https://lists.xenproject.org/archives/html/xen-devel/2017-06/msg03698.html
> From the summary, I have a  questions on
> "
>  - Roger: Registering config space with Xen before device discovery
>   will allow the hypervisor to set access traps for certain
>  functionality as appropriate"
> Traps will do emulation or something else ?

Have you read the series?

What else could the traps do? I'm not sure I understand the question.

>  Is the config space emulation only for DomU or it for Dom0 as well ?

Again, have you read the series? This is explained in the cover letter

On x86 this is initially for Dom0 only, DomU will continue to use QEMU
until the implementation inside the hypervisor (vPCI) is complete
enough to handle DomU securely.

> Slide 18 shows only for DomU ?

ARM folks believe this is not needed for Dom0 in the ARM case, I don't
have an opinion, I know it's certainly mandatory for x86 PVH Dom0.


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