Re: [PATCH v2 2/4] xen/arm: drop MAX_PAGES_PER_VCPU

[Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>]

On 12/19/25 9:22 AM, Orzel, Michal wrote:
> On 18/12/2025 19:19, Andrew Cooper wrote:
> > On 18/12/2025 5:28 pm, Oleksii Kurochko wrote:
> > > diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
> > > index 47973f99d9..e566023340 100644
> > > --- a/xen/arch/arm/domain.c
> > > +++ b/xen/arch/arm/domain.c
> > > @@ -473,36 +473,21 @@ void dump_pageframe_info(struct domain *d)
> > >   
> > >   }
> > >   
> > > -/*
> > > - * The new VGIC has a bigger per-IRQ structure, so we need more than one
> > > - * page on ARM64. Cowardly increase the limit in this case.
> > > - */
> > > -#if defined(CONFIG_NEW_VGIC) && defined(CONFIG_ARM_64)
> > > -#define MAX_PAGES_PER_VCPU  2
> > > -#else
> > > -#define MAX_PAGES_PER_VCPU  1
> > > -#endif
> > > -
> > >   struct vcpu *alloc_vcpu_struct(const struct domain *d)
> > >   {
> > >       struct vcpu *v;
> > >   
> > > -    BUILD_BUG_ON(sizeof(*v) > MAX_PAGES_PER_VCPU * PAGE_SIZE);
> > > -    v = alloc_xenheap_pages(get_order_from_bytes(sizeof(*v)), 0);
> > > -    if ( v != NULL )
> > > -    {
> > > -        unsigned int i;
> > > -
> > > -        for ( i = 0; i < DIV_ROUND_UP(sizeof(*v), PAGE_SIZE); i++ )
> > > -            clear_page((void *)v + i * PAGE_SIZE);
> > > -    }
> > > +    BUILD_BUG_ON(sizeof(*v) > PAGE_SIZE);
> > > +    v = alloc_xenheap_pages(0, 0);
> > I know this is only interim until the next patch, but
> > alloc_xenheap_page() to match the free function used.
> >
> > Personally, I'd merge patches 2 and 3 together, because everything you
> > touch in this patch is deleted by the next one.
> >
> > But, whatever the ARM maintainers prefer.
> I'm in favor of Andrew's suggestion. There's no point in introducing something
> in one patch and dropping it in the very next one.
Then I will merge patch 2 and 3.

~ Oleksii