[PATCH RFCv2 09/24] iommufd: Add IOMMU_HWPT_SET_DIRTY

[Joao Martins <joao.m.martins@oracle.com>]

Every IOMMU driver should be able to implement the needed iommu domain ops
to control dirty tracking.

Connect a hw_pagetable to the IOMMU core dirty tracking ops, specifically
the ability to enable/disable dirty tracking on an IOMMU domain
(hw_pagetable id). To that end add an io_pagetable kernel API to toggle
dirty tracking:

* iopt_set_dirty_tracking(iopt, [domain], state)

The intended caller of this is via the hw_pagetable object that is created.

Internally we will ensure the leftover dirty state is cleared /right
before/ we start dirty tracking. This is also useful for iommu drivers
which may decide that dirty tracking is always-enabled without being
able to disable it via iommu domain op.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
---
 drivers/iommu/iommufd/hw_pagetable.c    | 24 +++++++++++++++++
 drivers/iommu/iommufd/io_pagetable.c    | 36 +++++++++++++++++++++++++
 drivers/iommu/iommufd/iommufd_private.h | 11 ++++++++
 drivers/iommu/iommufd/main.c            |  3 +++
 include/uapi/linux/iommufd.h            | 27 +++++++++++++++++++
 5 files changed, 101 insertions(+)

diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c
index 4f0b72737ae2..7acbd88d05b7 100644
--- a/drivers/iommu/iommufd/hw_pagetable.c
+++ b/drivers/iommu/iommufd/hw_pagetable.c
@@ -200,3 +200,27 @@ int iommufd_hwpt_alloc(struct iommufd_ucmd *ucmd)
 	iommufd_put_object(&idev->obj);
 	return rc;
 }
+
+int iommufd_hwpt_set_dirty(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_hwpt_set_dirty *cmd = ucmd->cmd;
+	struct iommufd_hw_pagetable *hwpt;
+	struct iommufd_ioas *ioas;
+	int rc = -EOPNOTSUPP;
+	bool enable;
+
+	hwpt = iommufd_get_hwpt(ucmd, cmd->hwpt_id);
+	if (IS_ERR(hwpt))
+		return PTR_ERR(hwpt);
+
+	if (!hwpt->enforce_dirty)
+		return -EOPNOTSUPP;
+
+	ioas = hwpt->ioas;
+	enable = cmd->flags & IOMMU_DIRTY_TRACKING_ENABLED;
+
+	rc = iopt_set_dirty_tracking(&ioas->iopt, hwpt->domain, enable);
+
+	iommufd_put_object(&hwpt->obj);
+	return rc;
+}
diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c
index 187626e5f2bc..01adb0f7e4d0 100644
--- a/drivers/iommu/iommufd/io_pagetable.c
+++ b/drivers/iommu/iommufd/io_pagetable.c
@@ -479,6 +479,42 @@ int iopt_read_and_clear_dirty_data(struct io_pagetable *iopt,
 	down_read(&iopt->iova_rwsem);
 	ret = iommu_read_and_clear_dirty(domain, flags, bitmap);
 	up_read(&iopt->iova_rwsem);
+
+	return ret;
+}
+
+int iopt_set_dirty_tracking(struct io_pagetable *iopt,
+			    struct iommu_domain *domain, bool enable)
+{
+	const struct iommu_domain_ops *ops = domain->ops;
+	struct iommu_dirty_bitmap dirty;
+	struct iommu_iotlb_gather gather;
+	struct iopt_area *area;
+	int ret = 0;
+
+	if (!ops->set_dirty_tracking)
+		return -EOPNOTSUPP;
+
+	iommu_dirty_bitmap_init(&dirty, NULL, &gather);
+
+	down_write(&iopt->iova_rwsem);
+	for (area = iopt_area_iter_first(iopt, 0, ULONG_MAX);
+	     area && enable;
+	     area = iopt_area_iter_next(area, 0, ULONG_MAX)) {
+		ret = ops->read_and_clear_dirty(domain,
+						iopt_area_iova(area),
+						iopt_area_length(area), 0,
+						&dirty);
+		if (ret)
+			goto out_unlock;
+	}
+
+	iommu_iotlb_sync(domain, &gather);
+
+	ret = ops->set_dirty_tracking(domain, enable);
+
+out_unlock:
+	up_write(&iopt->iova_rwsem);
 	return ret;
 }
 
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 2259b15340e4..e902197a6a42 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -10,6 +10,7 @@
 #include <linux/uaccess.h>
 #include <linux/iommu.h>
 #include <linux/iova_bitmap.h>
+#include <uapi/linux/iommufd.h>
 
 struct iommu_domain;
 struct iommu_group;
@@ -83,6 +84,8 @@ int iopt_read_and_clear_dirty_data(struct io_pagetable *iopt,
 				   struct iommu_domain *domain,
 				   unsigned long flags,
 				   struct iommufd_dirty_data *bitmap);
+int iopt_set_dirty_tracking(struct io_pagetable *iopt,
+			    struct iommu_domain *domain, bool enable);
 
 void iommufd_access_notify_unmap(struct io_pagetable *iopt, unsigned long iova,
 				 unsigned long length);
@@ -267,6 +270,14 @@ struct iommufd_hw_pagetable {
 	struct list_head hwpt_item;
 };
 
+static inline struct iommufd_hw_pagetable *iommufd_get_hwpt(
+					struct iommufd_ucmd *ucmd, u32 id)
+{
+	return container_of(iommufd_get_object(ucmd->ictx, id,
+					       IOMMUFD_OBJ_HW_PAGETABLE),
+			    struct iommufd_hw_pagetable, obj);
+}
+int iommufd_hwpt_set_dirty(struct iommufd_ucmd *ucmd);
 struct iommufd_hw_pagetable *
 iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
 			   struct iommufd_device *idev, bool immediate_attach,
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 3932fe26522b..8c4640df0547 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -277,6 +277,7 @@ union ucmd_buffer {
 	struct iommu_ioas_unmap unmap;
 	struct iommu_option option;
 	struct iommu_vfio_ioas vfio_ioas;
+	struct iommu_hwpt_set_dirty set_dirty;
 #ifdef CONFIG_IOMMUFD_TEST
 	struct iommu_test_cmd test;
 #endif
@@ -318,6 +319,8 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
 		 val64),
 	IOCTL_OP(IOMMU_VFIO_IOAS, iommufd_vfio_ioas, struct iommu_vfio_ioas,
 		 __reserved),
+	IOCTL_OP(IOMMU_HWPT_SET_DIRTY, iommufd_hwpt_set_dirty,
+		 struct iommu_hwpt_set_dirty, __reserved),
 #ifdef CONFIG_IOMMUFD_TEST
 	IOCTL_OP(IOMMU_TEST_CMD, iommufd_test, struct iommu_test_cmd, last),
 #endif
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 1cd9c54d0f64..85498f14b3ae 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -46,6 +46,7 @@ enum {
 	IOMMUFD_CMD_OPTION,
 	IOMMUFD_CMD_VFIO_IOAS,
 	IOMMUFD_CMD_HWPT_ALLOC,
+	IOMMUFD_CMD_HWPT_SET_DIRTY,
 };
 
 /**
@@ -379,4 +380,30 @@ struct iommu_hwpt_alloc {
 	__u32 __reserved;
 };
 #define IOMMU_HWPT_ALLOC _IO(IOMMUFD_TYPE, IOMMUFD_CMD_HWPT_ALLOC)
+
+/**
+ * enum iommufd_set_dirty_flags - Flags for steering dirty tracking
+ * @IOMMU_DIRTY_TRACKING_DISABLED: Disables dirty tracking
+ * @IOMMU_DIRTY_TRACKING_ENABLED: Enables dirty tracking
+ */
+enum iommufd_hwpt_set_dirty_flags {
+	IOMMU_DIRTY_TRACKING_DISABLED = 0,
+	IOMMU_DIRTY_TRACKING_ENABLED = 1,
+};
+
+/**
+ * struct iommu_hwpt_set_dirty - ioctl(IOMMU_HWPT_SET_DIRTY)
+ * @size: sizeof(struct iommu_hwpt_set_dirty)
+ * @flags: Flags to control dirty tracking status.
+ * @hwpt_id: HW pagetable ID that represents the IOMMU domain.
+ *
+ * Toggle dirty tracking on an HW pagetable.
+ */
+struct iommu_hwpt_set_dirty {
+	__u32 size;
+	__u32 flags;
+	__u32 hwpt_id;
+	__u32 __reserved;
+};
+#define IOMMU_HWPT_SET_DIRTY _IO(IOMMUFD_TYPE, IOMMUFD_CMD_HWPT_SET_DIRTY)
 #endif
-- 
2.17.2