| Message ID | 20230616092654.175518-16-david@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | virtio-mem: Expose device memory through multiple memslots | expand |
diff --git a/hw/virtio/virtio-mem.c b/hw/virtio/virtio-mem.c index 516370067a..cccd834466 100644 --- a/hw/virtio/virtio-mem.c +++ b/hw/virtio/virtio-mem.c @@ -955,6 +955,12 @@ static void virtio_mem_prepare_memslots(VirtIOMEM *vmem) memory_region_init_alias(&vmem->memslots[idx], OBJECT(vmem), name, &vmem->memdev->mr, memslot_offset, memslot_size); + /* + * We want to be able to atomically and efficiently activate/deactivate + * individual memslots without affecting adjacent memslots in memory + * notifiers. + */ + memory_region_set_unmergeable(&vmem->memslots[idx], true); } }
Let's mark the memslot alias memory regions as unmergable, such that flatview and vhost won't merge adjacent memory region aliases and we can atomically map/unmap individual aliases without affecting adjacent alias memory regions. This fixes issues with vhost and vfio (which do not support atomic memslot updates) and avoids the temporary removal of large memslots, which can be an expensive operation. For example, vfio might have to unpin + repin a lot of memory, which is undesired. Signed-off-by: David Hildenbrand <david@redhat.com> --- hw/virtio/virtio-mem.c | 6 ++++++ 1 file changed, 6 insertions(+)