drivers/virtio/virtio_debug.c

// SPDX-License-Identifier: GPL-2.0-or-later

#include <linux/virtio.h>
#include <linux/virtio_config.h>
#include <linux/debugfs.h>

static struct dentry *virtio_debugfs_dir;

static int virtio_debug_device_features_show(struct seq_file *s, void *data)
{
	u64 device_features[VIRTIO_FEATURES_U64S];
	struct virtio_device *dev = s->private;
	unsigned int i;

	virtio_get_features(dev, device_features);
	for (i = 0; i < VIRTIO_FEATURES_BITS; i++) {
		if (virtio_features_test_bit(device_features, i))
			seq_printf(s, "%u\n", i);
	}
	return 0;
}
DEFINE_SHOW_ATTRIBUTE(virtio_debug_device_features);

static int virtio_debug_filter_features_show(struct seq_file *s, void *data)
{
	struct virtio_device *dev = s->private;
	unsigned int i;

	for (i = 0; i < VIRTIO_FEATURES_BITS; i++) {
		if (virtio_features_test_bit(dev->debugfs_filter_features, i))
			seq_printf(s, "%u\n", i);
	}
	return 0;
}
DEFINE_SHOW_ATTRIBUTE(virtio_debug_filter_features);

static int virtio_debug_filter_features_clear(void *data, u64 val)
{
	struct virtio_device *dev = data;

	if (val == 1)
		virtio_features_zero(dev->debugfs_filter_features);
	return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(virtio_debug_filter_features_clear_fops, NULL,
			 virtio_debug_filter_features_clear, "%llu\n");

static int virtio_debug_filter_feature_add(void *data, u64 val)
{
	struct virtio_device *dev = data;

	if (val >= VIRTIO_FEATURES_BITS)
		return -EINVAL;

	virtio_features_set_bit(dev->debugfs_filter_features, val);
	return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(virtio_debug_filter_feature_add_fops, NULL,
			 virtio_debug_filter_feature_add, "%llu\n");

static int virtio_debug_filter_feature_del(void *data, u64 val)
{
	struct virtio_device *dev = data;

	if (val >= VIRTIO_FEATURES_BITS)
		return -EINVAL;

	virtio_features_clear_bit(dev->debugfs_filter_features, val);
	return 0;
}

DEFINE_DEBUGFS_ATTRIBUTE(virtio_debug_filter_feature_del_fops, NULL,
			 virtio_debug_filter_feature_del, "%llu\n");

void virtio_debug_device_init(struct virtio_device *dev)
{
	dev->debugfs_dir = debugfs_create_dir(dev_name(&dev->dev),
					      virtio_debugfs_dir);
	debugfs_create_file("device_features", 0400, dev->debugfs_dir, dev,
			    &virtio_debug_device_features_fops);
	debugfs_create_file("filter_features", 0400, dev->debugfs_dir, dev,
			    &virtio_debug_filter_features_fops);
	debugfs_create_file("filter_features_clear", 0200, dev->debugfs_dir, dev,
			    &virtio_debug_filter_features_clear_fops);
	debugfs_create_file("filter_feature_add", 0200, dev->debugfs_dir, dev,
			    &virtio_debug_filter_feature_add_fops);
	debugfs_create_file("filter_feature_del", 0200, dev->debugfs_dir, dev,
			    &virtio_debug_filter_feature_del_fops);
}
EXPORT_SYMBOL_GPL(virtio_debug_device_init);

void virtio_debug_device_filter_features(struct virtio_device *dev)
{
	virtio_features_andnot(dev->features_array, dev->features_array,
			       dev->debugfs_filter_features);
}
EXPORT_SYMBOL_GPL(virtio_debug_device_filter_features);

void virtio_debug_device_exit(struct virtio_device *dev)
{
	debugfs_remove_recursive(dev->debugfs_dir);
}
EXPORT_SYMBOL_GPL(virtio_debug_device_exit);

void virtio_debug_init(void)
{
	virtio_debugfs_dir = debugfs_create_dir("virtio", NULL);
}
EXPORT_SYMBOL_GPL(virtio_debug_init);

void virtio_debug_exit(void)
{
	debugfs_remove_recursive(virtio_debugfs_dir);
}
EXPORT_SYMBOL_GPL(virtio_debug_exit);