Re: [Qemu-devel] [RFC PATCH qemu 3/4] memory: Share flat views and dispatch trees between address spaces

[Paolo Bonzini]

On 11/09/2017 14:08, Alexey Kardashevskiy wrote:
>> Ok, this makes sense.  Maybe it should be a flatview rather than an
>> AddressSpaceDispatch (a FlatView is essentially a list of
>> MemoryRegionSections; attaching the ASD to the FlatView is more or less
>> an implementation detail).
> The helpers I converted from AddressSpace to AddressSpaceDispatch do use
> dispatch structure only and do not use FlatView so it seemed logical.

Understood, but from a design POV FlatView makes more sense.

> btw this address_space in MemoryRegionSection - it does not seem to make
> much sense in the PhysPageMap::sections array, it only makes sense when
> MemoryRegionSection uses as a temporary object when calling listeners. Will
> it make sense if we enforce MemoryRegionSection::address_space to be NULL
> in the array and not NULL when used temporary?

memory_region_section_get_iotlb needs to access the AddressSpaceDispatch
for sections stored in the PhysPageMap array, because
memory_region_section_get_iotlb uses the ASD to compute the section index.

Paolo