Re: [PATCH] xen/arm: p2m: Populate pages for GICv2 mapping in arch_domain_create()

[Julien Grall <julien@xxxxxxx>]

Hi Henry,

On 13/10/2022 11:58, Julien Grall wrote:
> > > > +     * when the domain is created. Considering the worst case for page
> > > > +     * tables and keep a buffer, populate 16 pages to the P2M pages 
> > > > pool
> > > here.
> > > > +     */
> > > > +    if ( (rc = p2m_set_allocation(d, 16, NULL)) != 0 )
> > > > +    {
> > > > +        p2m_set_allocation(d, 0, NULL);
> > > Shouldn't this be done in p2m_fiinal_teardown() to cover so the pages
> > > will be freed anything after this call will fail (include in the caller
> > > domain_create())?
> > Hmm, yes, I will remove this p2m_set_allocation(d, 0, NULL); in v2.
> Just to clarify, I meant that a call in p2m_final_teardown() *is* 
> missing in p2m_final_teardown() (or wherever we decide to add).
> This would make this one redundant.
While chatting with you on IRC, I realized that a call to 
p2m_set_allocation() will only freed unused P2M pages. If some of them 
are in the P2M then they would be skipped.
This means we also need to call p2m_teardown() (which would need to be 
optionally preemptible).
Cheers,

--
Julien Grall