Re: [PATCH v3 05/19] xen/arm: mm: Add support for the contiguous bit

[Julien Grall <julien@xxxxxxx>]

Hi,

On 21/02/2022 10:22, Julien Grall wrote:
> @@ -1333,21 +1386,34 @@ static int xen_pt_update(unsigned long virt,
>       while ( left )
>       {
>           unsigned int order, level;
> +        unsigned int nr_contig;
> +        unsigned int new_flags;
>   
>           level = xen_pt_mapping_level(vfn, mfn, left, flags);
>           order = XEN_PT_LEVEL_ORDER(level);
>   
>           ASSERT(left >= BIT(order, UL));
>   
> -        rc = xen_pt_update_entry(root, pfn_to_paddr(vfn), mfn, level, flags);
> -        if ( rc )
> -            break;
> +        /*
> +         * Check if we can set the contiguous mapping and update the
> +         * flags accordingly.
> +         */
> +        nr_contig = xen_pt_check_contig(vfn, mfn, level, left, flags);
> +        new_flags = flags | ((nr_contig > 1) ? _PAGE_CONTIG : 0);
>   
> -        vfn += 1U << order;
> -        if ( !mfn_eq(mfn, INVALID_MFN) )
> -            mfn = mfn_add(mfn, 1U << order);
> +        for ( ; nr_contig > 0; nr_contig-- )
> +        {
> +            rc = xen_pt_update_entry(root, pfn_to_paddr(vfn), mfn, level,
> +                                     new_flags);
> +            if ( rc )
> +                break;
>   
> -        left -= (1U << order);
> +            vfn += 1U << order;
> +            if ( !mfn_eq(mfn, INVALID_MFN) )
> +                mfn = mfn_add(mfn, 1U << order);
> +
> +            left -= (1U << order);
> +        }
I forgot to add:

if ( rc )
  break;

Without it, the outer loop will never exit in case of an error.

Cheers,

--
Julien Grall