Re: [PATCH v3 2/3] xen: introduce arch_grant_(un)map_page_identity

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

Hi Stefano,

On 07/24/2014 02:31 PM, 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.
> 
> Base the implementation of arm_smmu_(un)map_page on
> arch_grant_(un)map_page_identity.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> 
> ---
> Changes in v3:
> - fix commit title;
> - use p2m_iommu types;
> - call arch_grant_(un)map_page_identity functions from
> arm_smmu_(un)map_page.
> ---
>  xen/arch/arm/p2m.c                 |   22 ++++++++++++++++++++++
>  xen/drivers/passthrough/arm/smmu.c |   13 ++-----------
>  xen/include/asm-arm/p2m.h          |    4 ++++
>  xen/include/asm-x86/p2m.h          |   13 +++++++++++++
>  4 files changed, 41 insertions(+), 11 deletions(-)
> 
> diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
> index 9960e17..6024b03 100644
> --- a/xen/arch/arm/p2m.c
> +++ b/xen/arch/arm/p2m.c
> @@ -555,6 +555,28 @@ 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;

NIT: I would add an ASSERT(!is_domain_direct_mapped(d)) for sanity check.

> +
> +    /* This is not an IOMMU mapping but it is not a regular RAM p2m type
> +     * either. We are using IOMMU p2m types here to prevent the pages
> +     * from being used as grants. */
> +    if ( writeable )
> +        t = p2m_iommu_map_rw;
> +    else
> +        t = p2m_iommu_map_ro;
> +
> +    return guest_physmap_add_entry(d, frame, frame, 0, t);
> +}
> +
> +int arch_grant_unmap_page_identity(struct domain *d, unsigned long frame)
> +{

Same here.

> +    guest_physmap_remove_page(d, frame, frame, 0);
> +    return 0;
> +}
> +

In any case:

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

Regards,

-- 
Julien Grall