Re: [PATCH v2 1/2] xen: introduce arch_iommu_grant_(un)map_page

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

Hi Stefano,

The Title of the commit message is now wrong.

On 23/07/14 18:19, Stefano Stabellini wrote:
> Introduce two arch specific functions to create a new p2m mapping of
> granted pages at pfn == mfn.
> The x86 implementation just returns ENOSYS.
>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> ---
>   xen/arch/arm/p2m.c        |   19 +++++++++++++++++++
>   xen/include/asm-arm/p2m.h |    4 ++++
>   xen/include/asm-x86/p2m.h |   13 +++++++++++++
>   3 files changed, 36 insertions(+)
>
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 9960e17..c38af59 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -555,6 +555,25 @@ void guest_physmap_remove_page(struct domain *d,
>                         pfn_to_paddr(mfn), MATTR_MEM, p2m_invalid);
>   }
>
> +int arch_grant_map_page_identity(struct domain *d, unsigned long frame,
> +                                 bool_t writeable)
> +{
> +    p2m_type_t t;
> +
> +    if ( writeable )
> +        t = p2m_ram_rw;
> +    else
> +        t = p2m_ram_ro;

This is not the right p2m type to use here. p2m_ram_{rw,ro} allow 
foreign mapping. So another guest could access to the grant.

I would use p2m_iommu_map_{rw,ro}.

Regards,

-- 
Julien Grall