Let's try to unplug completely offline big blocks first. Then, (if
enabled via unplug_offline) try to offline and remove whole big blocks.
No locking necessary - we can deal with concurrent onlining/offlining
just fine.
Note1: This is sub-optimal and might be dangerous in some environments: we
could end up in an infinite loop when offlining (e.g., long-term pinnings),
similar as with DIMMs. We'll introduce safe memory hotunplug via
fake-offlining next, and use this basic mode only when explicitly enabled.
Note2: Without ZONE_MOVABLE, memory unplug will be extremely unreliable
with bigger block sizes.
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <redacted>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Wei Yang <redacted>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: David Hildenbrand <redacted>
---
drivers/virtio/virtio_mem.c | 156 +++++++++++++++++++++++++++++++++++-
1 file changed, 155 insertions(+), 1 deletion(-)
diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index 94cf44b15cbf..6bcd0acbff32 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -388,6 +388,12 @@ static int virtio_mem_bbm_bb_states_prepare_next_bb(struct virtio_mem *vm)
_bb_id++) \
if (virtio_mem_bbm_get_bb_state(_vm, _bb_id) == _state)
+#define virtio_mem_bbm_for_each_bb_rev(_vm, _bb_id, _state) \
+ for (_bb_id = vm->bbm.next_bb_id - 1; \
+ _bb_id >= vm->bbm.first_bb_id && _vm->bbm.bb_count[_state]; \
+ _bb_id--) \
+ if (virtio_mem_bbm_get_bb_state(_vm, _bb_id) == _state)
+
/*
* Set the state of a memory block, taking care of the state counter.
*/
@@ -685,6 +691,18 @@ static int virtio_mem_sbm_remove_mb(struct virtio_mem *vm, unsigned long mb_id)
return virtio_mem_remove_memory(vm, addr, size);
}
+/*
+ * See virtio_mem_remove_memory(): Try to remove all Linux memory blocks covered
+ * by the big block.
+ */
+static int virtio_mem_bbm_remove_bb(struct virtio_mem *vm, unsigned long bb_id)
+{
+ const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
+ const uint64_t size = vm->bbm.bb_size;
+
+ return virtio_mem_remove_memory(vm, addr, size);
+}
+
/*
* Try offlining and removing memory from Linux.
*@@ -731,6 +749,19 @@ static int virtio_mem_sbm_offline_and_remove_mb(struct virtio_mem *vm,
return virtio_mem_offline_and_remove_memory(vm, addr, size);
}
+/*
+ * See virtio_mem_offline_and_remove_memory(): Try to offline and remove a
+ * all Linux memory blocks covered by the big block.
+ */
+static int virtio_mem_bbm_offline_and_remove_bb(struct virtio_mem *vm,
+ unsigned long bb_id)
+{
+ const uint64_t addr = virtio_mem_bb_id_to_phys(vm, bb_id);
+ const uint64_t size = vm->bbm.bb_size;
+
+ return virtio_mem_offline_and_remove_memory(vm, addr, size);
+}
+
/*
* Trigger the workqueue so the device can perform its magic.
*/@@ -1928,6 +1959,129 @@ static int virtio_mem_sbm_unplug_request(struct virtio_mem *vm, uint64_t diff)
return rc;
}
+/*
+ * Try to offline and remove a big block from Linux and unplug it. Will fail
+ * with -EBUSY if some memory is busy and cannot get unplugged.
+ *
+ * Will modify the state of the memory block. Might temporarily drop the
+ * hotplug_mutex.
+ */
+static int virtio_mem_bbm_offline_remove_and_unplug_bb(struct virtio_mem *vm,
+ unsigned long bb_id)
+{
+ int rc;
+
+ if (WARN_ON_ONCE(virtio_mem_bbm_get_bb_state(vm, bb_id) !=
+ VIRTIO_MEM_BBM_BB_ADDED))
+ return -EINVAL;
+
+ rc = virtio_mem_bbm_offline_and_remove_bb(vm, bb_id);
+ if (rc)
+ return rc;
+
+ rc = virtio_mem_bbm_unplug_bb(vm, bb_id);
+ if (rc)
+ virtio_mem_bbm_set_bb_state(vm, bb_id,
+ VIRTIO_MEM_BBM_BB_PLUGGED);
+ else
+ virtio_mem_bbm_set_bb_state(vm, bb_id,
+ VIRTIO_MEM_BBM_BB_UNUSED);
+ return rc;
+}
+
+/*
+ * Try to remove a big block from Linux and unplug it. Will fail with
+ * -EBUSY if some memory is online.
+ *
+ * Will modify the state of the memory block.
+ */
+static int virtio_mem_bbm_remove_and_unplug_bb(struct virtio_mem *vm,
+ unsigned long bb_id)
+{
+ int rc;
+
+ if (WARN_ON_ONCE(virtio_mem_bbm_get_bb_state(vm, bb_id) !=
+ VIRTIO_MEM_BBM_BB_ADDED))
+ return -EINVAL;
+
+ rc = virtio_mem_bbm_remove_bb(vm, bb_id);
+ if (rc)
+ return -EBUSY;
+
+ rc = virtio_mem_bbm_unplug_bb(vm, bb_id);
+ if (rc)
+ virtio_mem_bbm_set_bb_state(vm, bb_id,
+ VIRTIO_MEM_BBM_BB_PLUGGED);
+ else
+ virtio_mem_bbm_set_bb_state(vm, bb_id,
+ VIRTIO_MEM_BBM_BB_UNUSED);
+ return rc;
+}
+
+/*
+ * Test if a big block is completely offline.
+ */
+static bool virtio_mem_bbm_bb_is_offline(struct virtio_mem *vm,
+ unsigned long bb_id)
+{
+ const unsigned long start_pfn = PFN_DOWN(virtio_mem_bb_id_to_phys(vm, bb_id));
+ const unsigned long nr_pages = PFN_DOWN(vm->bbm.bb_size);
+ unsigned long pfn;
+
+ for (pfn = start_pfn; pfn < start_pfn + nr_pages;
+ pfn += PAGES_PER_SECTION) {