Re: [PATCH PROTOTYPE 3/6] vfio: Implement support for sparse RAM memory regions

[David Hildenbrand]

On 20.10.20 21:44, Peter Xu wrote:
> On Thu, Sep 24, 2020 at 06:04:20PM +0200, David Hildenbrand wrote:
>> Implement support for sparse RAM, to be used by virtio-mem. Handling
>> is somewhat-similar to memory_region_is_iommu() handling, which also
>> notifies on changes.
>>
>> Instead of mapping the whole region, we only map selected pieces (and
>> unmap previously selected pieces) when notified by the SparseRAMHandler.
> 
> It works with vIOMMU too, right? :) As long as vfio_get_vaddr() works as
> expected with virtio-mem plugging new memories, then I think the answer should
> be yes.
> 

I haven't tried, but I guess as it's simply mapped into
&address_space_memory, it should work just fine.

> If it's true, maybe worth mention it somewhere either in the commit message or
> in the code comment, because it seems not that obvious.

I will test and add, thanks for the hint!

> 
> So if you have plan to do some real IOs in your future tests, may also worth
> try with the "-device intel-iommu" and intel_iommu=on in the guest against the
> same test.

Thanks ... but I have an AMD system. Will try to find out how to get
that running with AMD :)

-- 
Thanks,

David / dhildenb