Re: [Xen-devel] [RFC] [Draft Design v2] ACPI/IORT Support in Xen.

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 16/11/17 12:39, Manish Jaggi wrote:
> On 11/16/2017 5:23 PM, Julien Grall wrote:
> > Hi Manish,
> >
> > On 16/11/17 11:46, Manish Jaggi wrote:
> > > On 11/16/2017 5:07 PM, Julien Grall wrote:
> > > > On 16/11/17 07:39, Manish Jaggi wrote:
> > > > > On 11/14/2017 6:53 PM, Julien Grall wrote:
> > > > > > > 3. IORT for Dom0
> > > > > > > -----------------
> > > > > > > IORT for Dom0 is based on host iort. Few nodes could be removed 
> > > > > > > or modified.
> > > > > > >   For instance
> > > > > > > - Host SMMU nodes should not be present as Xen should only touch it.
> > > > > > > - platform nodes (named components) may be controlled by xen 
> > > > > > > command line.
> > > > > > I am not sure where does this example come from? As I said, there 
> > > > > > are no plan to support Platform Device passthrough with ACPI. A 
> > > > > > better example here would removing PMCG.
> > > > > It came from review comments on my previous IORT SMMU hiding patch. 
> > > > > Andre suggested that Platform Nodes are needed.
> > > > > After some brainstorming with Julien we found two problems:
> > > > > 1) This only covers RC nodes, but not "named components" (platform
> > > > > devices), which we will need. ...
> > > > >
> > > > > From: 
> > > > > https://www.mail-archive.com/xen-devel@xxxxxxxxxxxxx/msg123434.html
> > > > I think you misunderstood my comment here... What I call "device 
> > > > passthrough" is giving access to a device to a domain other than the 
> > > > Hardware Domain
> > > > There are no plan for supporting platform device-passthrough on ACPI 
> > > > and I don't understand why you would like to control that using the 
> > > > command line.
> > > > What Andre was saying is your series was not covering the "named 
> > > > components" for the Hardware Domain.
> > > The section 3 is IORT for Dom0, where I mentioned that  some platform 
> > > devices can be hidden from dom0.
> > > So your comment on Platform device Passthrough might not be valid 
> > > then as it is for domU's only.
> > > Regarding the visibility of a platform device for dom0, I took cue 
> > > from your comment below
> > Where did I ever mention the command line solution? Please stop trying 
> > to put words in my mouth.
> > There are other reason than passthrough to hide device from the 
> > Hardware Domain.
> Lets put some clarity on the below items specifically for dom0
> a. can platform devices can be part of dom0 IORT ?
Yes. Otherwise, how would you be able to use MSI with platform device?

> b. If (a) yes, then how to decide on a finer grain the visibility of 
> platform devices for Dom0
>      Update ACPI tables to remove the device?
> c. Is fine grain visibility of platform device for dom0 to be covered in 
> my current patchset
No.

Cheers,

--
Julien Grall

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