After the previous patch, TLBs will be flushed on every change to
the memory mapping. This patch augments that with synchronization
of the MemoryRegionSections referred to in the iotlb array.
With this change, it is guaranteed that iotlb_to_region will access
the correct memory map, even once the TLB will be accessed outside
the BQL.
Backports commit 9d82b5a792236db31a75b9db5c93af69ac07c7c5 from qemu
This commit fixes the following issues:
- Any unmapped/free'd memory regions (MemoryRegion instances) are not
removed from the object property linked list of its owner (which is
always qdev_get_machine(uc)). This issue makes adding new memory
mapping by calling mem_map() or mem_map_ptr() slower as more and more
memory pages are mapped and unmapped - yes, even if those memory pages
are unmapped, they still impact the speed of future memory page
mappings due to this issue.
- FlatView is not reconstructed after a memory region is freed during
unmapping, which leads to a use-after-free the next time a new memory
region is mapped in address_space_update_topology().
