> Let's add a parent resource, named after the virtio device (inspired by
> drivers/dax/kmem.c). This allows user space to identify which memory
> belongs to which virtio-mem device.
>
> With this change and two virtio-mem devices:
> :/# cat /proc/iomem
> 00000000-00000fff : Reserved
> 00001000-0009fbff : System RAM
> [...]
> 140000000-333ffffff : virtio0
> 140000000-147ffffff : System RAM
> 148000000-14fffffff : System RAM
> 150000000-157ffffff : System RAM
> [...]
> 334000000-3033ffffff : virtio1
> 338000000-33fffffff : System RAM
> 340000000-347ffffff : System RAM
> 348000000-34fffffff : System RAM
> [...]
>
> Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
> Cc: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx>
> Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
> ---
> drivers/virtio/virtio_mem.c | 52 ++++++++++++++++++++++++++++++++++++-
> 1 file changed, 51 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
> index eb4c16d634e0..80cdb9e6b3c4 100644
> --- a/drivers/virtio/virtio_mem.c
> +++ b/drivers/virtio/virtio_mem.c
> @@ -99,6 +99,9 @@ struct virtio_mem {
> /* Id of the next memory bock to prepare when needed. */
> unsigned long next_mb_id;
>
> + /* The parent resource for all memory added via this device. */
> + struct resource *parent_resource;
> +
> /* Summary of all memory block states. */
> unsigned long nb_mb_state[VIRTIO_MEM_MB_STATE_COUNT];
> #define VIRTIO_MEM_NB_OFFLINE_THRESHOLD 10
> @@ -1741,6 +1744,44 @@ static int virtio_mem_init(struct virtio_mem *vm)
> return 0;
> }
>
> +static int virtio_mem_create_resource(struct virtio_mem *vm)
> +{
> + /*
> + * When force-unloading the driver and removing the device, we
> + * could have a garbage pointer. Duplicate the string.
> + */
> + const char *name = kstrdup(dev_name(&vm->vdev->dev), GFP_KERNEL);
> +
> + if (!name)
> + return -ENOMEM;
> +
> + vm->parent_resource = __request_mem_region(vm->addr, vm->region_size,
> + name, IORESOURCE_SYSTEM_RAM);
> + if (!vm->parent_resource) {
> + kfree(name);
> + dev_warn(&vm->vdev->dev, "could not reserve device region\n");
> + return -EBUSY;
> + }
> +
> + /* The memory is not actually busy - make add_memory() work. */
> + vm->parent_resource->flags &= ~IORESOURCE_BUSY;
> + return 0;
> +}
> +
> +static void virtio_mem_delete_resource(struct virtio_mem *vm)
> +{
> + const char *name;
> +
> + if (!vm->parent_resource)
> + return;
> +
> + name = vm->parent_resource->name;
> + release_resource(vm->parent_resource);
> + kfree(vm->parent_resource);
> + kfree(name);
> + vm->parent_resource = NULL;
> +}
> +
> static int virtio_mem_probe(struct virtio_device *vdev)
> {
> struct virtio_mem *vm;
> @@ -1770,11 +1811,16 @@ static int virtio_mem_probe(struct virtio_device *vdev)
> if (rc)
> goto out_del_vq;
>
> + /* create the parent resource for all memory */
> + rc = virtio_mem_create_resource(vm);
> + if (rc)
> + goto out_del_vq;
> +
> /* register callbacks */
> vm->memory_notifier.notifier_call = virtio_mem_memory_notifier_cb;
> rc = register_memory_notifier(&vm->memory_notifier);
> if (rc)
> - goto out_del_vq;
> + goto out_del_resource;
> rc = register_virtio_mem_device(vm);
> if (rc)
> goto out_unreg_mem;
> @@ -1788,6 +1834,8 @@ static int virtio_mem_probe(struct virtio_device *vdev)
> return 0;
> out_unreg_mem:
> unregister_memory_notifier(&vm->memory_notifier);
> +out_del_resource:
> + virtio_mem_delete_resource(vm);
> out_del_vq:
> vdev->config->del_vqs(vdev);
> out_free_vm:
> @@ -1848,6 +1896,8 @@ static void virtio_mem_remove(struct virtio_device *vdev)
> vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL] ||
> vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE_MOVABLE])
> dev_warn(&vdev->dev, "device still has system memory added\n");
> + else
> + virtio_mem_delete_resource(vm);
>
> /* remove all tracking data - no locking needed */
> vfree(vm->mb_state);
> --
Reviewed-by: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx>
