[PATCH v3 11/15] virtio-mem: Add parent resource for all added "System RAM"

David Hildenbrand
2020-05-07T10:33:39Z

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@redhat.com>
Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
---
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);
--
2.25.3