Re: [PATCH] xen/arm: Fix P2M root page tables invalidation

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

On 6/16/25 10:15 AM, Julien Grall wrote:

> (+Oleksii)
>       
>       
>       Hi,
>       
>       
>       Adding Oleksii for visibility.
>       
>     
Thanks for adding me.

>       
>       On 16/06/2025 07:56, Michal Orzel wrote:
>       
> > Fix the condition part of the for loop in
> >         p2m_invalidate_root() that
> >         
> >         uses P2M_ROOT_LEVEL instead of P2M_ROOT_PAGES. The goal here is
> >         to
> >         
> >       
>     
I used P2M_ROOT_PAGES for RISC-V for the similar case. This patch just confirms
that it was a correct decision.

Thanks.

~ Oleksii

> > invalidate all root page tables (that can
> >         be concatenated), so the loop
> >         
> >         must iterate through all these pages. Root level can be 0 or 1,
> >         whereas
> >         
> >         there can be 1,2,8,16 root pages. The issue may lead to some
> >         pages
> >         
> >         not being invalidated and therefore the guest access won't be
> >         trapped.
> >         
> >         We use it to track pages accessed by guest for set/way emulation
> >         provided
> >         
> >         no IOMMU, IOMMU not enabled for the domain or P2M not shared
> >         with IOMMU.
> >         
> >         
> >         Fixes: 2148a125b73b ("xen/arm: Track page accessed between batch
> >         of Set/Way operations")
> >         
> >         Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
> >         
> >       
>       
>       Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>
>       
>       
>       Cheers,
>       
>       
>