185ecf40e3
The data plane thread needs to map guest physical addresses to host pointers. Normally this is done with cpu_physical_memory_map() but the function assumes the global mutex is held. The data plane thread does not touch the global mutex and therefore needs a thread-safe memory mapping mechanism. Hostmem registers a MemoryListener similar to how vhost collects and pushes memory region information into the kernel. There is a fine-grained lock on the regions list which is held during lookup and when installing a new regions list. When the physical memory map changes the MemoryListener callbacks are invoked. They build up a new list of memory regions which is finally installed when the list has been completed. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Read the documentation in qemu-doc.html or on http://wiki.qemu.org - QEMU team