Implement bus_map_resource on arm64

[andrew]

Summary

This will allow us to allocate an unmapped memory resource, then
later map it with a specific memory attribute.

[jhb]

Hmm, I should post some of my reviews. I have a branch that does this for most architectures but I also added some helpers to reduce code duplication in activate/deactive_resource methods. I also tried to fix some layering violations that I should perhaps untangle as that made the branch larger. The helpers at least are probably useful so I'll try to resurrect those soon.

[sdmitry_parallels.com]

In D29694#666735, @jhb wrote:

Hmm, I should post some of my reviews. I have a branch that does this for most architectures but I also added some helpers to reduce code duplication in activate/deactive_resource methods. I also tried to fix some layering violations that I should perhaps untangle as that made the branch larger. The helpers at least are probably useful so I'll try to resurrect those soon.

I'd want to upvote implementation of bus_map_resource() for arm64, because it is an essential change to make virtio_pci_modern work on arm64

[andrew]

In D29694#666735, @jhb wrote:

Hmm, I should post some of my reviews. I have a branch that does this for most architectures but I also added some helpers to reduce code duplication in activate/deactive_resource methods. I also tried to fix some layering violations that I should perhaps untangle as that made the branch larger. The helpers at least are probably useful so I'll try to resurrect those soon.

Are you planning to do this soon? If not I'd like to commit this so I can clean up some other code that manages device memory.