Re: [PATCH 1/3] xen: arm: avoid reusing incorrect mappings when walking the p2m.

[Julien Grall <julien.grall@linaro.org>]

Hi Ian,

On 07/14/2014 05:27 PM, Ian Campbell wrote:
> If we handle a change in a superpage then we need to invalidate any cached
> mappings further down, otherwise we risk using them because their offset might
> match but be based on a different offset further up the table.
> 
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> ---
>  xen/arch/arm/p2m.c |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index c0c011a..917baa3 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -719,6 +719,8 @@ static int apply_p2m_changes(struct domain *d,
>                  goto out;
>              }
>              cur_first_page = p2m_first_level_index(addr);
> +            /* Any mapping further down is now invalid */
> +            cur_second_offset = ~0;

I think you miss to invalid cur_first_offset.

Also, I think we have the same issue on Xen 4.4.

Regards,

-- 
Julien Grall