vfio: Introduce the DMA logging feature support

Introduce the DMA logging feature support in the vfio core layer.

It includes the processing of the device start/stop/report DMA logging
UAPIs and calling the relevant driver 'op' to do the work.

Specifically,
Upon start, the core translates the given input ranges into an interval
tree, checks for unexpected overlapping, non aligned ranges and then
pass the translated input to the driver for start tracking the given
ranges.

Upon report, the core translates the given input user space bitmap and
page size into an IOVA kernel bitmap iterator. Then it iterates it and
call the driver to set the corresponding bits for the dirtied pages in a
specific IOVA range.

Upon stop, the driver is called to stop the previous started tracking.

The next patches from the series will introduce the mlx5 driver
implementation for the logging ops.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Link: https://lore.kernel.org/r/20220908183448.195262-6-yishaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 26 insertions, 2 deletions

diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index e05ddc6fe6a5..0e2826559091 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -14,6 +14,7 @@
 #include <linux/workqueue.h>
 #include <linux/poll.h>
 #include <uapi/linux/vfio.h>
+#include <linux/iova_bitmap.h>
 
 struct kvm;
 
@@ -33,10 +34,11 @@ struct vfio_device {
 	struct device *dev;
 	const struct vfio_device_ops *ops;
 	/*
-	 * mig_ops is a static property of the vfio_device which must be set
-	 * prior to registering the vfio_device.
+	 * mig_ops/log_ops is a static property of the vfio_device which must
+	 * be set prior to registering the vfio_device.
 	 */
 	const struct vfio_migration_ops *mig_ops;
+	const struct vfio_log_ops *log_ops;
 	struct vfio_group *group;
 	struct vfio_device_set *dev_set;
 	struct list_head dev_set_list;
@@ -109,6 +111,28 @@ struct vfio_migration_ops {
 };
 
 /**
+ * @log_start: Optional callback to ask the device start DMA logging.
+ * @log_stop: Optional callback to ask the device stop DMA logging.
+ * @log_read_and_clear: Optional callback to ask the device read
+ *         and clear the dirty DMAs in some given range.
+ *
+ * The vfio core implementation of the DEVICE_FEATURE_DMA_LOGGING_ set
+ * of features does not track logging state relative to the device,
+ * therefore the device implementation of vfio_log_ops must handle
+ * arbitrary user requests. This includes rejecting subsequent calls
+ * to log_start without an intervening log_stop, as well as graceful
+ * handling of log_stop and log_read_and_clear from invalid states.
+ */
+struct vfio_log_ops {
+	int (*log_start)(struct vfio_device *device,
+		struct rb_root_cached *ranges, u32 nnodes, u64 *page_size);
+	int (*log_stop)(struct vfio_device *device);
+	int (*log_read_and_clear)(struct vfio_device *device,
+		unsigned long iova, unsigned long length,
+		struct iova_bitmap *dirty);
+};
+
+/**
  * vfio_check_feature - Validate user input for the VFIO_DEVICE_FEATURE ioctl
  * @flags: Arg from the device_feature op
  * @argsz: Arg from the device_feature op