Re: [Xen-devel] [PATCH 1/4] xen: re-introduce support for grant v2 interface

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

> +int arch_gnttab_map_status(uint64_t *frames, unsigned long nr_gframes,
> +                        unsigned long max_nr_gframes,
> +                        grant_status_t **__shared)
> +{
> +     grant_status_t *shared = *__shared;
> +     unsigned long addr;
> +     unsigned long i;
> +
> +     if (shared == NULL)
> +             *__shared = shared = gnttab_status_vm_area.area->addr;
> +
> +     addr = (unsigned long)shared;
> +
> +     for (i = 0; i < nr_gframes; i++) {
> +             set_pte_at(&init_mm, addr, gnttab_status_vm_area.ptes[i],
> +                        mfn_pte(frames[i], PAGE_KERNEL));
> +             addr += PAGE_SIZE;
> +     }
> +
> +     return 0;
> +}

This looks pretty much identical to arch_gnttab_map_shared() except for
gnttab_shared_vm_area vs. gnttab_status_vm_area,which can be passed in
as a parameter.

> +
>  void arch_gnttab_unmap(void *shared, unsigned long nr_gframes)
>  {
> +     pte_t **ptes;
>       unsigned long addr;
>       unsigned long i;
>  
> +     if (shared == gnttab_status_vm_area.area->addr)
> +             ptes = gnttab_status_vm_area.ptes;
> +     else
> +             ptes = gnttab_shared_vm_area.ptes;
> +
>       addr = (unsigned long)shared;
>  
>       for (i = 0; i < nr_gframes; i++) {
> -             set_pte_at(&init_mm, addr, gnttab_shared_vm_area.ptes[i],
> -                        __pte(0));
> +             set_pte_at(&init_mm, addr, ptes[i], __pte(0));
>               addr += PAGE_SIZE;
>       }

And this too looks like can be factored out (to something like
arch_update_gnttab()). But perhaps not in this patch.

>  }
> @@ -102,12 +129,35 @@ static int arch_gnttab_valloc(struct gnttab_vm_area 
> *area, unsigned nr_frames)
>       return 0;
>  }
>  
> -int arch_gnttab_init(unsigned long nr_shared)
> +static void arch_gnttab_vfree(struct gnttab_vm_area *area)
>  {
> +     free_vm_area(area->area);
> +     kfree(area->ptes);
> +}

Not sure there is need for this routine. It is used only once.

Also, as an overall comment -- It feels like there may be too many
BUG_ON()s.


-boris

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