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

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 07/24/2014 05:57 PM, Stefano Stabellini wrote:
> On Thu, 24 Jul 2014, Julien Grall wrote:
>> 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@xxxxxxxxxxxxx>
>>>
>>> ---
>>> 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.
>>
> 
> you mean ASSERT(is_domain_direct_mapped(d))

Yes. Sorry.

>>> +
>>> +    /* 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@xxxxxxxxxx>
> 
> thanks
> 


-- 
Julien Grall

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