[PATCH v5 2/4] iommufd: Add IOMMUFD_CMD_SET_DEV_DATA and IOMMUFD_CMD_UNSET_DEV_DATA

[Nicolin Chen]

Add a new pair of ioctls to allow user space to set and unset its iommu-
specific device data at the iommu that a passthrough device is behind.

On platforms with SMMUv3, this new uAPIs will be used to forward a user
space virtual Stream ID of a passthrough device to link to its physical
Stream ID and log into a lookup table, in order for the host kernel to
later run sanity on ATC invalidation requests from the user space, with
ATC_INV commands that have SID fields (virtual Stream IDs).

Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
---
 drivers/iommu/iommufd/device.c          |  2 +
 drivers/iommu/iommufd/iommufd_private.h |  1 +
 drivers/iommu/iommufd/main.c            | 85 +++++++++++++++++++++++++
 include/uapi/linux/iommufd.h            | 32 ++++++++++
 4 files changed, 120 insertions(+)

diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
index 7f238c583b61..37a234371645 100644
--- a/drivers/iommu/iommufd/device.c
+++ b/drivers/iommu/iommufd/device.c
@@ -136,6 +136,8 @@ void iommufd_device_destroy(struct iommufd_object *obj)
 	struct iommufd_device *idev =
 		container_of(obj, struct iommufd_device, obj);
 
+	if (idev->has_user_data)
+		dev_iommu_ops(idev->dev)->unset_dev_user_data(idev->dev);
 	iommu_device_release_dma_owner(idev->dev);
 	iommufd_put_group(idev->igroup);
 	if (!iommufd_selftest_is_mock_dev(idev->dev))
diff --git a/drivers/iommu/iommufd/iommufd_private.h b/drivers/iommu/iommufd/iommufd_private.h
index 9ae6edea697f..b8abf664d3f8 100644
--- a/drivers/iommu/iommufd/iommufd_private.h
+++ b/drivers/iommu/iommufd/iommufd_private.h
@@ -313,6 +313,7 @@ struct iommufd_device {
 	/* always the physical device */
 	struct device *dev;
 	bool enforce_cache_coherency;
+	bool has_user_data;
 };
 
 static inline struct iommufd_device *
diff --git a/drivers/iommu/iommufd/main.c b/drivers/iommu/iommufd/main.c
index 255e8a3c5b0e..d49837397dfa 100644
--- a/drivers/iommu/iommufd/main.c
+++ b/drivers/iommu/iommufd/main.c
@@ -387,6 +387,85 @@ static int iommufd_option(struct iommufd_ucmd *ucmd)
 	return 0;
 }
 
+static int iommufd_set_dev_data(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_set_dev_data *cmd = ucmd->cmd;
+	struct iommufd_device *idev;
+	const struct iommu_ops *ops;
+	void *data = NULL;
+	int rc;
+
+	if (!cmd->data_uptr || !cmd->data_len)
+		return -EINVAL;
+
+	idev = iommufd_get_device(ucmd, cmd->dev_id);
+	if (IS_ERR(idev))
+		return PTR_ERR(idev);
+
+	mutex_lock(&idev->igroup->lock);
+	if (idev->has_user_data) {
+		rc = -EEXIST;
+		goto out_unlock;
+	}
+
+	ops = dev_iommu_ops(idev->dev);
+	if (!ops->dev_user_data_len ||
+	    !ops->set_dev_user_data ||
+	    !ops->unset_dev_user_data) {
+		rc = -EOPNOTSUPP;
+		goto out_unlock;
+	}
+
+	data = kzalloc(ops->dev_user_data_len, GFP_KERNEL);
+	if (!data) {
+		rc = -ENOMEM;
+		goto out_unlock;
+	}
+
+	if (copy_struct_from_user(data, ops->dev_user_data_len,
+				  u64_to_user_ptr(cmd->data_uptr),
+				  cmd->data_len)) {
+		rc = -EFAULT;
+		goto out_free_data;
+	}
+
+	rc = ops->set_dev_user_data(idev->dev, data);
+	if (rc)
+		goto out_free_data;
+
+	idev->has_user_data = true;
+out_free_data:
+	kfree(data);
+out_unlock:
+	mutex_unlock(&idev->igroup->lock);
+	iommufd_put_object(&idev->obj);
+	return rc;
+}
+
+static int iommufd_unset_dev_data(struct iommufd_ucmd *ucmd)
+{
+	struct iommu_unset_dev_data *cmd = ucmd->cmd;
+	struct iommufd_device *idev;
+	int rc = 0;
+
+	idev = iommufd_get_device(ucmd, cmd->dev_id);
+	if (IS_ERR(idev))
+		return PTR_ERR(idev);
+
+	mutex_lock(&idev->igroup->lock);
+	if (!idev->has_user_data) {
+		rc = -ENOENT;
+		goto out_unlock;
+	}
+
+	dev_iommu_ops(idev->dev)->unset_dev_user_data(idev->dev);
+	idev->has_user_data = false;
+out_unlock:
+	mutex_unlock(&idev->igroup->lock);
+	iommufd_put_object(&idev->obj);
+	return rc;
+}
+
 union ucmd_buffer {
 	struct iommu_destroy destroy;
 	struct iommu_hw_info info;
@@ -400,6 +479,8 @@ union ucmd_buffer {
 	struct iommu_ioas_unmap unmap;
 	struct iommu_option option;
 	struct iommu_resv_iova_ranges resv_ranges;
+	struct iommu_set_dev_data set_dev_data;
+	struct iommu_unset_dev_data unset_dev_data;
 	struct iommu_vfio_ioas vfio_ioas;
 #ifdef CONFIG_IOMMUFD_TEST
 	struct iommu_test_cmd test;
@@ -446,6 +527,10 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = {
 		 val64),
 	IOCTL_OP(IOMMU_RESV_IOVA_RANGES, iommufd_resv_iova_ranges,
 		 struct iommu_resv_iova_ranges, resv_iovas),
+	IOCTL_OP(IOMMU_SET_DEV_DATA, iommufd_set_dev_data,
+		 struct iommu_set_dev_data, data_len),
+	IOCTL_OP(IOMMU_UNSET_DEV_DATA, iommufd_unset_dev_data,
+		 struct iommu_unset_dev_data, dev_id),
 	IOCTL_OP(IOMMU_VFIO_IOAS, iommufd_vfio_ioas, struct iommu_vfio_ioas,
 		 __reserved),
 #ifdef CONFIG_IOMMUFD_TEST
diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h
index 034da283cd3a..ede822e5acbb 100644
--- a/include/uapi/linux/iommufd.h
+++ b/include/uapi/linux/iommufd.h
@@ -49,6 +49,8 @@ enum {
 	IOMMUFD_CMD_GET_HW_INFO,
 	IOMMUFD_CMD_RESV_IOVA_RANGES,
 	IOMMUFD_CMD_HWPT_INVALIDATE,
+	IOMMUFD_CMD_SET_DEV_DATA,
+	IOMMUFD_CMD_UNSET_DEV_DATA,
 };
 
 /**
@@ -508,4 +510,34 @@ struct iommu_hwpt_invalidate {
 	__aligned_u64 data_uptr;
 };
 #define IOMMU_HWPT_INVALIDATE _IO(IOMMUFD_TYPE, IOMMUFD_CMD_HWPT_INVALIDATE)
+
+/**
+ * struct iommu_set_dev_data - ioctl(IOMMU_SET_DEV_DATA)
+ * @size: sizeof(struct iommu_set_dev_data)
+ * @dev_id: The device to set an iommu specific device data
+ * @data_uptr: User pointer of the device user data
+ * @data_len: Length of the device user data
+ *
+ * The device data must be unset using ioctl(IOMMU_UNSET_DEV_DATA), before
+ * another ioctl(IOMMU_SET_DEV_DATA) call or before the device itself gets
+ * unbind'd from the iommufd context.
+ */
+struct iommu_set_dev_data {
+	__u32 size;
+	__u32 dev_id;
+	__aligned_u64 data_uptr;
+	__u32 data_len;
+};
+#define IOMMU_SET_DEV_DATA _IO(IOMMUFD_TYPE, IOMMUFD_CMD_SET_DEV_DATA)
+
+/**
+ * struct iommu_unset_dev_data - ioctl(IOMMU_UNSET_DEV_DATA)
+ * @size: sizeof(struct iommu_unset_dev_data)
+ * @dev_id: The device to unset its device user data
+ */
+struct iommu_unset_dev_data {
+	__u32 size;
+	__u32 dev_id;
+};
+#define IOMMU_UNSET_DEV_DATA _IO(IOMMUFD_TYPE, IOMMUFD_CMD_UNSET_DEV_DATA)
 #endif
-- 
2.41.0