@@ -178,4 +178,13 @@ config VIRTIO_DMA_SHARED_BUFFER
This option adds a flavor of dma buffers that are backed by
virtio resources.
+config VIRTIO_DEBUG
+ bool "Debug facilities"
+ help
+ Enable this to expose debug facilities over debugfs.
+ This allows to debug features, to see what features the device
+ advertises and to set filter for features used by driver.
+
+ If unsure, say N.
+
endif # VIRTIO_MENU
@@ -13,3 +13,4 @@ obj-$(CONFIG_VIRTIO_INPUT) += virtio_input.o
obj-$(CONFIG_VIRTIO_VDPA) += virtio_vdpa.o
obj-$(CONFIG_VIRTIO_MEM) += virtio_mem.o
obj-$(CONFIG_VIRTIO_DMA_SHARED_BUFFER) += virtio_dma_buf.o
+obj-$(CONFIG_VIRTIO_DEBUG) += virtio_debug.o
@@ -274,6 +274,9 @@ static int virtio_dev_probe(struct device *_d)
else
dev->features = driver_features_legacy & device_features;
+ /* When debugging, user may filter some features by hand. */
+ virtio_debug_device_filter_features(dev);
+
/* Transport features always preserved to pass to finalize_features. */
for (i = VIRTIO_TRANSPORT_F_START; i < VIRTIO_TRANSPORT_F_END; i++)
if (device_features & (1ULL << i))
@@ -463,6 +466,8 @@ int register_virtio_device(struct virtio_device *dev)
/* Acknowledge that we've seen the device. */
virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
+ virtio_debug_device_init(dev);
+
/*
* device_add() causes the bus infrastructure to look for a matching
* driver.
@@ -494,6 +499,7 @@ void unregister_virtio_device(struct virtio_device *dev)
int index = dev->index; /* save for after device release */
device_unregister(&dev->dev);
+ virtio_debug_device_exit(dev);
ida_free(&virtio_index_ida, index);
}
EXPORT_SYMBOL_GPL(unregister_virtio_device);
@@ -588,11 +594,13 @@ static int virtio_init(void)
{
if (bus_register(&virtio_bus) != 0)
panic("virtio bus registration failed");
+ virtio_debug_init();
return 0;
}
static void __exit virtio_exit(void)
{
+ virtio_debug_exit();
bus_unregister(&virtio_bus);
ida_destroy(&virtio_index_ida);
}
new file mode 100644
@@ -0,0 +1,109 @@
+// 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)
+{
+ struct virtio_device *dev = s->private;
+ u64 device_features;
+ unsigned int i;
+
+ device_features = dev->config->get_features(dev);
+ for (i = 0; i < BITS_PER_LONG_LONG; i++) {
+ if (device_features & (1ULL << 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 < BITS_PER_LONG_LONG; i++) {
+ if (dev->debugfs_filter_features & (1ULL << 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)
+ dev->debugfs_filter_features = 0;
+ 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 >= BITS_PER_LONG_LONG)
+ return -EINVAL;
+ dev->debugfs_filter_features |= BIT_ULL_MASK(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 >= BITS_PER_LONG_LONG)
+ return -EINVAL;
+ dev->debugfs_filter_features &= ~BIT_ULL_MASK(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);
+}
+
+void virtio_debug_device_filter_features(struct virtio_device *dev)
+{
+ dev->features &= ~dev->debugfs_filter_features;
+}
+
+void virtio_debug_device_exit(struct virtio_device *dev)
+{
+ debugfs_remove_recursive(dev->debugfs_dir);
+}
+
+void virtio_debug_init(void)
+{
+ virtio_debugfs_dir = debugfs_create_dir("virtio", NULL);
+}
+
+void virtio_debug_exit(void)
+{
+ debugfs_remove_recursive(virtio_debugfs_dir);
+}
@@ -126,6 +126,8 @@ struct virtio_admin_cmd {
* @vqs: the list of virtqueues for this device.
* @features: the features supported by both driver and device.
* @priv: private pointer for the driver's use.
+ * @debugfs_dir: debugfs directory entry.
+ * @debugfs_filter_features: features to be filtered set by debugfs.
*/
struct virtio_device {
int index;
@@ -141,6 +143,10 @@ struct virtio_device {
struct list_head vqs;
u64 features;
void *priv;
+#ifdef CONFIG_VIRTIO_DEBUG
+ struct dentry *debugfs_dir;
+ u64 debugfs_filter_features;
+#endif
};
#define dev_to_virtio(_dev) container_of_const(_dev, struct virtio_device, dev)
@@ -234,4 +240,33 @@ void virtqueue_dma_sync_single_range_for_cpu(struct virtqueue *_vq, dma_addr_t a
void virtqueue_dma_sync_single_range_for_device(struct virtqueue *_vq, dma_addr_t addr,
unsigned long offset, size_t size,
enum dma_data_direction dir);
+
+#ifdef CONFIG_VIRTIO_DEBUG
+void virtio_debug_device_init(struct virtio_device *dev);
+void virtio_debug_device_exit(struct virtio_device *dev);
+void virtio_debug_device_filter_features(struct virtio_device *dev);
+void virtio_debug_init(void);
+void virtio_debug_exit(void);
+#else
+static inline void virtio_debug_device_init(struct virtio_device *dev)
+{
+}
+
+static inline void virtio_debug_device_exit(struct virtio_device *dev)
+{
+}
+
+static inline void virtio_debug_device_filter_features(struct virtio_device *dev)
+{
+}
+
+static inline void virtio_debug_init(void)
+{
+}
+
+static inline void virtio_debug_exit(void)
+{
+}
+#endif
+
#endif /* _LINUX_VIRTIO_H */