Re: [V6 PATCH 6.2/7] pvh dom0: Add and remove foreign pages

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

On 12/11/2013 12:44 AM, Mukesh Rathor wrote:
> Grrrr... sent too soon before compiling on arm... here's version
> with arm compile fixed. thanks.
>
> -------------
>
> In this patch, a new function, p2m_add_foreign(), is added
> to map pages from foreign guest into current dom0 for domU creation.
> Such pages are typed p2m_map_foreign. Another function
> p2m_remove_foreign() is added to remove such pages. Note, in
> the remove path, we must release the refcount that was taken during
> the map phase. This is done in p2m_remove_page, which also addresses
> releasing of refcnt when the domain is destroyed.
>
> Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
> ---

[..]

>
> diff --git a/xen/include/asm-arm/p2m.h b/xen/include/asm-arm/p2m.h
> index c660820..03d34e9 100644
> --- a/xen/include/asm-arm/p2m.h
> +++ b/xen/include/asm-arm/p2m.h
> @@ -83,7 +83,7 @@ static inline struct page_info *get_page_from_gfn(
>       struct page_info *page;
>       unsigned long mfn = gmfn_to_mfn(d, gfn);
>
> -    ASSERT(t == NULL);
> +    ASSERT(*t == INT_MAX);

There is various place where get_page_from_gfn where t == NULL. With 
this solution it will segfault every time.

I would do something like that:
   if (*t)
     t = INT_MAX;

-- 
Julien Grall