Re: [Qemu-ppc] [Qemu-devel] [PATCH qemu v17 06/12] memory: Add reporting of supported page sizes

[Alexey Kardashevskiy]

On 08/06/16 16:00, David Gibson wrote:
> On Mon, Jun 06, 2016 at 03:31:04PM +0200, Paolo Bonzini wrote:
>>
>>
>> On 02/06/2016 05:35, David Gibson wrote:
>>> On Wed, Jun 01, 2016 at 06:57:37PM +1000, Alexey Kardashevskiy wrote:
>>>>> Every IOMMU has some granularity which MemoryRegionIOMMUOps::translate
>>>>> uses when translating, however this information is not available outside
>>>>> the translate context for various checks.
>>>>>
>>>>> This adds a get_page_sizes callback to MemoryRegionIOMMUOps and
>>>>> a wrapper for it so IOMMU users (such as VFIO) can know the actual
>>>>> page size(s) used by an IOMMU.
>>>>>
>>>>> As IOMMU MR represents a guest IOMMU, this uses TARGET_PAGE_SIZE
>>>>> as fallback.
>>>>>
>>>>> This removes vfio_container_granularity() and uses new helper in
>>>>> memory_region_iommu_replay() when replaying IOMMU mappings on added
>>>>> IOMMU memory region.
>>>>>
>>>>> Signed-off-by: Alexey Kardashevskiy <address@hidden>
>>>>> Reviewed-by: David Gibson <address@hidden>
>>> Paolo,
>>>
>>> Looks like you were left off the CC for this one.
>>>
>>> I think this is ready to go - do you want to merge, comment or ack and
>>> we'll take it either through my tree or Alex's?
>>
>> It's okay for you to merge, but the callback should be called
>> "get_page_size" or "get_replay_granularity".  The plural is weird.
> 
> Hm, no, it really could return multiple page sizes if the logical
> (guest side) IOMMU supports them.

It could but it does not now and I cannot see it coming in near future so I
am really confused now about the naming and what the callback should return
- one page size or a mask. What should it be now?


> That might be useful at some point
> in the future.  For now, it's sufficient for the replay to use the
> smallest pagesize.
> 


-- 
Alexey

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