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

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

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
(0/9).

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.

Roger.

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