[RFC 2/3] vfio: Add VFIO_DEVICE_PASID_[AT|DE]TACH_IOMMUFD_PT

[Yi Liu <yi.l.liu@intel.com>]

This adds ioctls for the userspace to attach a given pasid of a vfio
device to/from an IOAS/HWPT.

Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
 drivers/vfio/device_cdev.c | 45 +++++++++++++++++++++++++++++++
 drivers/vfio/vfio.h        |  4 +++
 drivers/vfio/vfio_main.c   |  8 ++++++
 include/uapi/linux/vfio.h  | 55 ++++++++++++++++++++++++++++++++++++++
 4 files changed, 112 insertions(+)

diff --git a/drivers/vfio/device_cdev.c b/drivers/vfio/device_cdev.c
index e75da0a70d1f..c2ac7ed44537 100644
--- a/drivers/vfio/device_cdev.c
+++ b/drivers/vfio/device_cdev.c
@@ -210,6 +210,51 @@ int vfio_df_ioctl_detach_pt(struct vfio_device_file *df,
 	return 0;
 }
 
+int vfio_df_ioctl_pasid_attach_pt(struct vfio_device_file *df,
+				  struct vfio_device_pasid_attach_iommufd_pt __user *arg)
+{
+	struct vfio_device *device = df->device;
+	struct vfio_device_pasid_attach_iommufd_pt attach;
+	unsigned long minsz;
+	int ret;
+
+	minsz = offsetofend(struct vfio_device_pasid_attach_iommufd_pt, pt_id);
+
+	if (copy_from_user(&attach, arg, minsz))
+		return -EFAULT;
+
+	if (attach.argsz < minsz || attach.flags)
+		return -EINVAL;
+
+	mutex_lock(&device->dev_set->lock);
+	ret = device->ops->pasid_attach_ioas(device, attach.pasid, &attach.pt_id);
+	mutex_unlock(&device->dev_set->lock);
+
+	return ret;
+}
+
+int vfio_df_ioctl_pasid_detach_pt(struct vfio_device_file *df,
+				  struct vfio_device_pasid_detach_iommufd_pt __user *arg)
+{
+	struct vfio_device *device = df->device;
+	struct vfio_device_pasid_detach_iommufd_pt detach;
+	unsigned long minsz;
+
+	minsz = offsetofend(struct vfio_device_pasid_detach_iommufd_pt, flags);
+
+	if (copy_from_user(&detach, arg, minsz))
+		return -EFAULT;
+
+	if (detach.argsz < minsz || detach.flags)
+		return -EINVAL;
+
+	mutex_lock(&device->dev_set->lock);
+	device->ops->pasid_detach_ioas(device, detach.pasid);
+	mutex_unlock(&device->dev_set->lock);
+
+	return 0;
+}
+
 static char *vfio_device_devnode(const struct device *dev, umode_t *mode)
 {
 	return kasprintf(GFP_KERNEL, "vfio/devices/%s", dev_name(dev));
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 307e3f29b527..d228cdb6b345 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -353,6 +353,10 @@ int vfio_df_ioctl_attach_pt(struct vfio_device_file *df,
 			    struct vfio_device_attach_iommufd_pt __user *arg);
 int vfio_df_ioctl_detach_pt(struct vfio_device_file *df,
 			    struct vfio_device_detach_iommufd_pt __user *arg);
+int vfio_df_ioctl_pasid_attach_pt(struct vfio_device_file *df,
+				  struct vfio_device_pasid_attach_iommufd_pt __user *arg);
+int vfio_df_ioctl_pasid_detach_pt(struct vfio_device_file *df,
+				  struct vfio_device_pasid_detach_iommufd_pt __user *arg);
 
 #if IS_ENABLED(CONFIG_VFIO_DEVICE_CDEV)
 void vfio_init_device_cdev(struct vfio_device *device);
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 40732e8ed4c6..850bbaebdd29 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -1230,6 +1230,14 @@ static long vfio_device_fops_unl_ioctl(struct file *filep,
 		case VFIO_DEVICE_DETACH_IOMMUFD_PT:
 			ret = vfio_df_ioctl_detach_pt(df, uptr);
 			goto out;
+
+		case VFIO_DEVICE_PASID_ATTACH_IOMMUFD_PT:
+			ret = vfio_df_ioctl_pasid_attach_pt(df, uptr);
+			goto out;
+
+		case VFIO_DEVICE_PASID_DETACH_IOMMUFD_PT:
+			ret = vfio_df_ioctl_pasid_detach_pt(df, uptr);
+			goto out;
 		}
 	}
 
diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h
index 97ab68a175e0..474bb314d135 100644
--- a/include/uapi/linux/vfio.h
+++ b/include/uapi/linux/vfio.h
@@ -975,6 +975,61 @@ struct vfio_device_detach_iommufd_pt {
 
 #define VFIO_DEVICE_DETACH_IOMMUFD_PT		_IO(VFIO_TYPE, VFIO_BASE + 20)
 
+/*
+ * VFIO_DEVICE_PASID_ATTACH_IOMMUFD_PT - _IOW(VFIO_TYPE, VFIO_BASE + 21,
+ *					      struct vfio_device_pasid_attach_iommufd_pt)
+ * @argsz:	User filled size of this data.
+ * @flags:	Must be 0.
+ * @pasid:	The pasid to be attached.
+ * @pt_id:	Input the target id which can represent an ioas or a hwpt
+ *		allocated via iommufd subsystem.
+ *		Output the input ioas id or the attached hwpt id which could
+ *		be the specified hwpt itself or a hwpt automatically created
+ *		for the specified ioas by kernel during the attachment.
+ *
+ * Associate a pasid (of a cdev device) with an address space within the
+ * bound iommufd. Undo by VFIO_DEVICE_PASID_DETACH_IOMMUFD_PT or device fd
+ * close. This is only allowed on cdev fds.
+ *
+ * If a pasid is currently attached to a valid hw_pagetable (hwpt), without
+ * doing a VFIO_DEVICE_PASID_DETACH_IOMMUFD_PT, a second
+ * VFIO_DEVICE_PASID_ATTACH_IOMMUFD_PT ioctl passing in another hwpt id is
+ * allowed. This action, also known as a hwpt replacement, will replace the
+ * pasid's currently attached hwpt with a new hwpt corresponding to the given
+ * @pt_id.
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+struct vfio_device_pasid_attach_iommufd_pt {
+	__u32	argsz;
+	__u32	flags;
+	__u32	pasid;
+	__u32	pt_id;
+};
+
+#define VFIO_DEVICE_PASID_ATTACH_IOMMUFD_PT	_IO(VFIO_TYPE, VFIO_BASE + 21)
+
+/*
+ * VFIO_DEVICE_PASID_DETACH_IOMMUFD_PT - _IOW(VFIO_TYPE, VFIO_BASE + 22,
+ *					      struct vfio_device_pasid_detach_iommufd_pt)
+ * @argsz:	User filled size of this data.
+ * @flags:	Must be 0.
+ * @pasid:	The pasid to be detached.
+ *
+ * Remove the association of a pasid (of a cdev device) and its current
+ * associated address space.  After it, the pasid of the device should be in
+ * a blocking DMA state.  This is only allowed on cdev fds.
+ *
+ * Return: 0 on success, -errno on failure.
+ */
+struct vfio_device_pasid_detach_iommufd_pt {
+	__u32	argsz;
+	__u32	flags;
+	__u32	pasid;
+};
+
+#define VFIO_DEVICE_PASID_DETACH_IOMMUFD_PT	_IO(VFIO_TYPE, VFIO_BASE + 22)
+
 /*
  * Provide support for setting a PCI VF Token, which is used as a shared
  * secret between PF and VF drivers.  This feature may only be set on a
-- 
2.34.1