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From:   David Hildenbrand <david@redhat.com>
To:     linux-kernel@vger.kernel.org
Cc:     linux-mm@kvack.org, virtualization@lists.linux-foundation.org,
        Andrew Morton <akpm@linux-foundation.org>,
        "Michael S . Tsirkin" <mst@redhat.com>,
        David Hildenbrand <david@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Subject: [PATCH v1 23/29] virtio-mem: factor out adding/removing memory from Linux
Date:   Mon, 12 Oct 2020 14:53:17 +0200
Message-Id: <20201012125323.17509-24-david@redhat.com>
In-Reply-To: <20201012125323.17509-1-david@redhat.com>
References: <20201012125323.17509-1-david@redhat.com>
MIME-Version: 1.0
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Let's use wrappers for the low-level functions that dev_dbg/dev_warn
and work on addr + size, such that we can reuse them for adding/removing
in other granularity.

We only warn when adding memory failed, because that's something to pay
attention to. We won't warn when removing failed, we'll reuse that in
racy context soon (and we do have proper BUG_ON() statements in the
current cases where it must never happen).

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
 drivers/virtio/virtio_mem.c | 107 ++++++++++++++++++++++++------------
 1 file changed, 73 insertions(+), 34 deletions(-)

diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
index d3ab04f655ee..eb2ad31a8d8a 100644
--- a/drivers/virtio/virtio_mem.c
+++ b/drivers/virtio/virtio_mem.c
@@ -453,18 +453,16 @@ static bool virtio_mem_could_add_memory(struct virtio_mem *vm, uint64_t size)
 }
 
 /*
- * Try to add a memory block to Linux. This will usually only fail
- * if out of memory.
+ * Try adding memory to Linux. Will usually only fail if out of memory.
  *
  * Must not be called with the vm->hotplug_mutex held (possible deadlock with
  * onlining code).
  *
- * Will not modify the state of the memory block.
+ * Will not modify the state of memory blocks in virtio-mem.
  */
-static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id)
+static int virtio_mem_add_memory(struct virtio_mem *vm, uint64_t addr,
+				 uint64_t size)
 {
-	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
-	const uint64_t size = memory_block_size_bytes();
 	int rc;
 
 	/*
@@ -478,32 +476,50 @@ static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id)
 			return -ENOMEM;
 	}
 
-	dev_dbg(&vm->vdev->dev, "adding memory block: %lu\n", mb_id);
+	dev_dbg(&vm->vdev->dev, "adding memory: 0x%llx - 0x%llx\n", addr,
+		addr + size - 1);
 	/* Memory might get onlined immediately. */
 	atomic64_add(size, &vm->offline_size);
 	rc = add_memory_driver_managed(vm->nid, addr, size, vm->resource_name,
 				       MEMHP_MERGE_RESOURCE);
-	if (rc)
+	if (rc) {
 		atomic64_sub(size, &vm->offline_size);
+		dev_warn(&vm->vdev->dev, "adding memory failed: %d\n", rc);
+		/*
+		 * TODO: Linux MM does not properly clean up yet in all cases
+		 * where adding of memory failed - especially on -ENOMEM.
+		 */
+	}
 	return rc;
 }
 
 /*
- * Try to remove a memory block from Linux. Will only fail if the memory block
- * is not offline.
+ * See virtio_mem_add_memory(): Try adding a single Linux memory block.
+ */
+static int virtio_mem_sbm_add_mb(struct virtio_mem *vm, unsigned long mb_id)
+{
+	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
+	const uint64_t size = memory_block_size_bytes();
+
+	return virtio_mem_add_memory(vm, addr, size);
+}
+
+/*
+ * Try removing memory from Linux. Will only fail if memory blocks aren't
+ * offline.
  *
  * Must not be called with the vm->hotplug_mutex held (possible deadlock with
  * onlining code).
  *
- * Will not modify the state of the memory block.
+ * Will not modify the state of memory blocks in virtio-mem.
  */
-static int virtio_mem_mb_remove(struct virtio_mem *vm, unsigned long mb_id)
+static int virtio_mem_remove_memory(struct virtio_mem *vm, uint64_t addr,
+				    uint64_t size)
 {
-	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
-	const uint64_t size = memory_block_size_bytes();
 	int rc;
 
-	dev_dbg(&vm->vdev->dev, "removing memory block: %lu\n", mb_id);
+	dev_dbg(&vm->vdev->dev, "removing memory: 0x%llx - 0x%llx\n", addr,
+		addr + size - 1);
 	rc = remove_memory(vm->nid, addr, size);
 	if (!rc) {
 		atomic64_sub(size, &vm->offline_size);
@@ -512,27 +528,41 @@ static int virtio_mem_mb_remove(struct virtio_mem *vm, unsigned long mb_id)
 		 * immediately instead of waiting.
 		 */
 		virtio_mem_retry(vm);
+	} else {
+		dev_dbg(&vm->vdev->dev, "removing memory failed: %d\n", rc);
 	}
 	return rc;
 }
 
 /*
- * Try to offline and remove a memory block from Linux.
+ * See virtio_mem_remove_memory(): Try removing a single Linux memory block.
+ */
+static int virtio_mem_sbm_remove_mb(struct virtio_mem *vm, unsigned long mb_id)
+{
+	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
+	const uint64_t size = memory_block_size_bytes();
+
+	return virtio_mem_remove_memory(vm, addr, size);
+}
+
+/*
+ * Try offlining and removing memory from Linux.
  *
  * Must not be called with the vm->hotplug_mutex held (possible deadlock with
  * onlining code).
  *
- * Will not modify the state of the memory block.
+ * Will not modify the state of memory blocks in virtio-mem.
  */
-static int virtio_mem_mb_offline_and_remove(struct virtio_mem *vm,
-					    unsigned long mb_id)
+static int virtio_mem_offline_and_remove_memory(struct virtio_mem *vm,
+						uint64_t addr,
+						uint64_t size)
 {
-	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
-	const uint64_t size = memory_block_size_bytes();
 	int rc;
 
-	dev_dbg(&vm->vdev->dev, "offlining and removing memory block: %lu\n",
-		mb_id);
+	dev_dbg(&vm->vdev->dev,
+		"offlining and removing memory: 0x%llx - 0x%llx\n", addr,
+		addr + size - 1);
+
 	rc = offline_and_remove_memory(vm->nid, addr, size);
 	if (!rc) {
 		atomic64_sub(size, &vm->offline_size);
@@ -541,10 +571,26 @@ static int virtio_mem_mb_offline_and_remove(struct virtio_mem *vm,
 		 * immediately instead of waiting.
 		 */
 		virtio_mem_retry(vm);
+	} else {
+		dev_dbg(&vm->vdev->dev,
+			"offlining and removing memory failed: %d\n", rc);
 	}
 	return rc;
 }
 
+/*
+ * See virtio_mem_offline_and_remove_memory(): Try offlining and removing
+ * a single Linux memory block.
+ */
+static int virtio_mem_sbm_offline_and_remove_mb(struct virtio_mem *vm,
+						unsigned long mb_id)
+{
+	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
+	const uint64_t size = memory_block_size_bytes();
+
+	return virtio_mem_offline_and_remove_memory(vm, addr, size);
+}
+
 /*
  * Trigger the workqueue so the device can perform its magic.
  */
@@ -1230,17 +1276,10 @@ static int virtio_mem_sbm_plug_and_add_mb(struct virtio_mem *vm,
 					    VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL);
 
 	/* Add the memory block to linux - if that fails, try to unplug. */
-	rc = virtio_mem_mb_add(vm, mb_id);
+	rc = virtio_mem_sbm_add_mb(vm, mb_id);
 	if (rc) {
 		int new_state = VIRTIO_MEM_SBM_MB_UNUSED;
 
-		dev_err(&vm->vdev->dev,
-			"adding memory block %lu failed with %d\n", mb_id, rc);
-
-		/*
-		 * TODO: Linux MM does not properly clean up yet in all cases
-		 * where adding of memory failed - especially on -ENOMEM.
-		 */
 		if (virtio_mem_sbm_unplug_sb(vm, mb_id, 0, count))
 			new_state = VIRTIO_MEM_SBM_MB_PLUGGED;
 		virtio_mem_sbm_set_mb_state(vm, mb_id, new_state);
@@ -1411,7 +1450,7 @@ static int virtio_mem_sbm_unplug_any_sb_offline(struct virtio_mem *vm,
 					    VIRTIO_MEM_SBM_MB_UNUSED);
 
 		mutex_unlock(&vm->hotplug_mutex);
-		rc = virtio_mem_mb_remove(vm, mb_id);
+		rc = virtio_mem_sbm_remove_mb(vm, mb_id);
 		BUG_ON(rc);
 		mutex_lock(&vm->hotplug_mutex);
 	}
@@ -1504,7 +1543,7 @@ static int virtio_mem_sbm_unplug_any_sb_online(struct virtio_mem *vm,
 	 */
 	if (virtio_mem_sbm_test_sb_unplugged(vm, mb_id, 0, vm->sbm.sbs_per_mb)) {
 		mutex_unlock(&vm->hotplug_mutex);
-		rc = virtio_mem_mb_offline_and_remove(vm, mb_id);
+		rc = virtio_mem_sbm_offline_and_remove_mb(vm, mb_id);
 		mutex_lock(&vm->hotplug_mutex);
 		if (!rc)
 			virtio_mem_sbm_set_mb_state(vm, mb_id,
@@ -1991,7 +2030,7 @@ static void virtio_mem_remove(struct virtio_device *vdev)
 	 */
 	virtio_mem_sbm_for_each_mb(vm, mb_id,
 				   VIRTIO_MEM_SBM_MB_OFFLINE_PARTIAL) {
-		rc = virtio_mem_mb_remove(vm, mb_id);
+		rc = virtio_mem_sbm_remove_mb(vm, mb_id);
 		BUG_ON(rc);
 		virtio_mem_sbm_set_mb_state(vm, mb_id,
 					    VIRTIO_MEM_SBM_MB_UNUSED);
-- 
2.26.2