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[PATCH v4 18/18] virtio-mem: Mark memslot alias memory regions unmergeab
From: |
David Hildenbrand |
Subject: |
[PATCH v4 18/18] virtio-mem: Mark memslot alias memory regions unmergeable |
Date: |
Tue, 26 Sep 2023 20:57:38 +0200 |
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 handles vhost and vfio in multiple-memslot mode correctly (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.
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
hw/virtio/virtio-mem.c | 6 ++++++
1 file changed, 6 insertions(+)
diff --git a/hw/virtio/virtio-mem.c b/hw/virtio/virtio-mem.c
index e1e4250e69..9dc3c61b5a 100644
--- a/hw/virtio/virtio-mem.c
+++ b/hw/virtio/virtio-mem.c
@@ -940,6 +940,12 @@ 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);
}
}
--
2.41.0
- [PATCH v4 11/18] vhost: Add vhost_get_max_memslots(), (continued)
- [PATCH v4 11/18] vhost: Add vhost_get_max_memslots(), David Hildenbrand, 2023/09/26
- [PATCH v4 12/18] memory-device, vhost: Support automatic decision on the number of memslots, David Hildenbrand, 2023/09/26
- [PATCH v4 17/18] memory, vhost: Allow for marking memory device memory regions unmergeable, David Hildenbrand, 2023/09/26
- [PATCH v4 13/18] memory: Clarify mapping requirements for RamDiscardManager, David Hildenbrand, 2023/09/26
- [PATCH v4 14/18] virtio-mem: Pass non-const VirtIOMEM via virtio_mem_range_cb, David Hildenbrand, 2023/09/26
- [PATCH v4 15/18] virtio-mem: Update state to match bitmap as soon as it's been migrated, David Hildenbrand, 2023/09/26
- [PATCH v4 16/18] virtio-mem: Expose device memory dynamically via multiple memslots if enabled, David Hildenbrand, 2023/09/26
- [PATCH v4 18/18] virtio-mem: Mark memslot alias memory regions unmergeable,
David Hildenbrand <=