Re: [Xen-devel] [PATCH v5 7/8] xen: arm: use superpages in p2m when pages are suitably aligned

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Ian,

On 07/09/2014 01:07 PM, Ian Campbell wrote:
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index cb22e9c..642591b 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c

[..]

> +    case CACHEFLUSH:
> +        if ( !p2m_valid(orig_pte) )
> +        {
> +            *addr = (*addr + level_size) & level_mask;
> +            return P2M_ONE_PROGRESS_NOP;
> +        }
> +
> +        if ( level < 3 && p2m_table(orig_pte) )
> +            return P2M_ONE_DESCEND;
> +        /*
> +         * could flush up to the next boundary, but would need to be
> +         * careful about preemption, so just do one page now and loop.

At the first glance I though this code didn't handle correctly superpage
flush. It took me several minutes to understand that you rely
P2M_ONE_PROGRESS{,_NOP} to do the job for you.

Can you explain this trick in the commit message?

With this changes:

Acked-by: Julien Grall <julien.grall@xxxxxxxxxx>

Regards,

-- 
Julien Grall

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