Refactor RamDiscardManager to aggregate multiple RamDiscardSource
instances. This enables scenarios where multiple components (e.g.,
virtio-mem and RamBlockAttributes) can coordinate memory discard
state for the same memory region.
The aggregation uses:
- Populated: ALL sources populated
- Discarded: ANY source discarded
When a source is added with existing listeners, they are notified
about regions that become discarded. When a source is removed,
listeners are notified about regions that become populated.
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Link: https://lore.kernel.org/r/20260604-rdm5-v5-7-5768e6a0943d@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
cc9c77f4dd