Re: [PATCH 02/12] xen/arm: add cache coloring initialization for domains

[Jan Beulich <jbeulich@suse.com>]

On 21.10.2022 20:02, Julien Grall wrote:
> On 26/08/2022 13:51, Carlo Nonato wrote:
>> This commit adds array pointers to domains as well as to the hypercall
>> and configuration structure employed in domain creation. The latter is used
>> both by the toolstack and by Xen itself to pass configuration data to the
>> domain creation function, so the XEN_GUEST_HANDLE macro must be adopted to be
>> able to access guest memory in the first case. This implies special care for
>> the copy of the configuration data into the domain data, meaning that a
>> discrimination variable for the two possible code paths (coming from Xen or
>> from the toolstack) is needed.
> 
> So this means that a toolstack could set from_guest. I know the 
> toolstack is trusted... However, we should try to limit when the trust 
> when this is possible.
> 
> In this case, I would consider to modify the prototype of 
> domain_create() to pass internal information.

Since I was pointed at this in the context of reviewing v4: The way a
clone of domain_create() was introduced there is, as pointed out there,
not scalable. Imo the prototype shouldn't change unless really needed
(i.e. benefiting at least a fair share of callers), and clones like
this one also shouldn't be introduced.

Hopefully this is all moot now anyway, with - as it looks - there being
agreement that this won't need to be part of domain_create() anymore.

Jan