Re: [Xen-devel] [PATCH v4 07/17] xen/arm: ITS: Add virtual ITS commands support

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Fri, 2015-07-17 at 16:15 +0100, Julien Grall wrote:

> >>
> >> Also, you have to translate the col_id into to a VCPU ID.
> > 
> > This is virtual collection id which itself is vcpu id. isn't it?
> 
> No. A collection can move between CPU, so you will end up to have vCPUID
> != vCID.

Specifically it is a TA (TargetAddress)  and not a collection which is
equal to a VCPU ID (in our implementation, because we have chosen to
implement GITS_TYPER.PTA==0).

A collection is mapped onto a TA by MAPC command.

Thus some sort of record of which collection is mapped to which
TA(==vcpuid) is required.

> Your MAPC command is correctly storing the mapping in collections, so
> please use it to retrieve the correct vCPU.

Indeed.



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