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Re: [Xen-devel] [PATCH v6 4/6] xen/arm: zynqmp: implement zynqmp_eemi

On Mon, 17 Dec 2018, Julien Grall wrote:
> Hi Stefano,
> On 17/12/2018 18:50, Stefano Stabellini wrote:
> > On Mon, 17 Dec 2018, Julien Grall wrote:
> >> On 14/12/2018 19:11, Stefano Stabellini wrote:
> >>> +forward_to_fw:
> >>
> >> On the previous version, I have requested a comment in the code explaining 
> >> why
> >> forward the commands without sanity check.
> > 
> > I added something above but I can add something here too and make it 
> > clearer.
> I can't find any explanation in the patch. Could you point out where you 
> added it?

I wrote above domain_has_node_access:

 * Power domain node_ids identify the area of effect of the power
 * management operations. They are the first parameter passed to power
 * management EEMI calls.
 * Reset IDs identify the area of effect of a reset operation. They are
 * the first parameter passed to reset EEMI calls.
 * For now, let the hardware domain access to all power domain nodes and
 * all reset lines. In the future, we'll check for ownership of
 * resources by specific virtual machines. 

This is the new comment I plan to add just before fowarding the SMC:

  * ZynqMP firmware calls (EEMI) take an argument that specifies the
  * area of effect of the function called. Specifically, node ids for
  * power management functions and reset ids for reset functions.
  * The code above checks if a virtual machine has access rights over
  * the node id, reset id, etc. Now that the check has been done, we
  * can forward the whole command to firmware without additional
  * parameters checks.

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