virtio-mem: determine nid only once using memory_add_physaddr_to_nid()

Let's determine the target nid only once in case we have none specified -
usually, we'll end up with node 0 either way.
Reviewed-by: Wei Yang <richard.weiyang@linux.alibaba.com>
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
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>
Link: https://lore.kernel.org/r/20201112133815.13332-2-david@redhat.comSigned-off-by: Michael S. Tsirkin <mst@redhat.com>

drivers/virtio/virtio_mem.c

@@ -70,7 +70,7 @@ struct virtio_mem {
 
 	/* The device block size (for communicating with the device). */
 	uint64_t device_block_size;
-	/* The translated node id. NUMA_NO_NODE in case not specified. */
+	/* The determined node id for all memory of the device. */
 	int nid;
 	/* Physical start address of the memory region. */
 	uint64_t addr;
@@ -406,10 +406,6 @@ static int virtio_mem_sb_bitmap_prepare_next_mb(struct virtio_mem *vm)
 static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id)
 {
 	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
-	int nid = vm->nid;
-
-	if (nid == NUMA_NO_NODE)
-		nid = memory_add_physaddr_to_nid(addr);
 
 	/*
 	 * When force-unloading the driver and we still have memory added to
@@ -423,7 +419,8 @@ static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id)
 	}
 
 	dev_dbg(&vm->vdev->dev, "adding memory block: %lu\n", mb_id);
-	return add_memory_driver_managed(nid, addr, memory_block_size_bytes(),
+	return add_memory_driver_managed(vm->nid, addr,
+					 memory_block_size_bytes(),
 					 vm->resource_name,
 					 MEMHP_MERGE_RESOURCE);
 }
@@ -440,13 +437,9 @@ static int virtio_mem_mb_add(struct virtio_mem *vm, unsigned long mb_id)
 static int virtio_mem_mb_remove(struct virtio_mem *vm, unsigned long mb_id)
 {
 	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
-	int nid = vm->nid;
-
-	if (nid == NUMA_NO_NODE)
-		nid = memory_add_physaddr_to_nid(addr);
 
 	dev_dbg(&vm->vdev->dev, "removing memory block: %lu\n", mb_id);
-	return remove_memory(nid, addr, memory_block_size_bytes());
+	return remove_memory(vm->nid, addr, memory_block_size_bytes());
 }
 
 /*
@@ -461,14 +454,11 @@ static int virtio_mem_mb_offline_and_remove(struct virtio_mem *vm,
 					    unsigned long mb_id)
 {
 	const uint64_t addr = virtio_mem_mb_id_to_phys(mb_id);
-	int nid = vm->nid;
-
-	if (nid == NUMA_NO_NODE)
-		nid = memory_add_physaddr_to_nid(addr);
 
 	dev_dbg(&vm->vdev->dev, "offlining and removing memory block: %lu\n",
 		mb_id);
-	return offline_and_remove_memory(nid, addr, memory_block_size_bytes());
+	return offline_and_remove_memory(vm->nid, addr,
+					 memory_block_size_bytes());
 }
 
 /*
@@ -1659,6 +1649,10 @@ static int virtio_mem_init(struct virtio_mem *vm)
 	virtio_cread_le(vm->vdev, struct virtio_mem_config, region_size,
 			&vm->region_size);
 
+	/* Determine the nid for the device based on the lowest address. */
+	if (vm->nid == NUMA_NO_NODE)
+		vm->nid = memory_add_physaddr_to_nid(vm->addr);
+
 	/*
 	 * We always hotplug memory in memory block granularity. This way,
 	 * we have to wait for exactly one memory block to online.
@@ -1707,7 +1701,7 @@ static int virtio_mem_init(struct virtio_mem *vm)
 		 memory_block_size_bytes());
 	dev_info(&vm->vdev->dev, "subblock size: 0x%llx",
 		 (unsigned long long)vm->subblock_size);
-	if (vm->nid != NUMA_NO_NODE)
+	if (vm->nid != NUMA_NO_NODE && IS_ENABLED(CONFIG_NUMA))
 		dev_info(&vm->vdev->dev, "nid: %d", vm->nid);
 
 	return 0;