[RFC 08/12] vfio: Add infrastructure for bind_iommufd and attach

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

This prepares to add ioctls for device cdev fd. This infrastructure includes:
    - vfio_iommufd_bind() to accept pt_id, and also return back dev_id to caller.
    - vfio_iommufd_attach() to support iommufd pgtable attach after bind_iommufd.

Signed-off-by: Yi Liu <yi.l.liu@intel.com>
---
 drivers/vfio/group.c     | 12 +++++-
 drivers/vfio/iommufd.c   | 79 ++++++++++++++++++++++++++++++----------
 drivers/vfio/vfio.h      | 15 ++++++--
 drivers/vfio/vfio_main.c | 10 +++--
 4 files changed, 88 insertions(+), 28 deletions(-)

diff --git a/drivers/vfio/group.c b/drivers/vfio/group.c
index 1030a0ad3cf1..c4d0564874f2 100644
--- a/drivers/vfio/group.c
+++ b/drivers/vfio/group.c
@@ -157,6 +157,8 @@ static int vfio_group_ioctl_set_container(struct vfio_group *group,
 static int vfio_device_group_open(struct vfio_device_file *df)
 {
 	struct vfio_device *device = df->device;
+	u32 ioas_id;
+	u32 *pt_id = NULL;
 	int ret;
 
 	mutex_lock(&device->group->group_lock);
@@ -165,6 +167,14 @@ static int vfio_device_group_open(struct vfio_device_file *df)
 		goto err_unlock_group;
 	}
 
+	if (device->group->iommufd) {
+		ret = iommufd_vfio_compat_ioas_id(device->group->iommufd,
+						  &ioas_id);
+		if (ret)
+			goto err_unlock_group;
+		pt_id = &ioas_id;
+	}
+
 	mutex_lock(&device->dev_set->lock);
 	/*
 	 * Here we pass the KVM pointer with the group under the lock.  If the
@@ -174,7 +184,7 @@ static int vfio_device_group_open(struct vfio_device_file *df)
 	df->kvm = device->group->kvm;
 	df->iommufd = device->group->iommufd;
 
-	ret = vfio_device_open(df);
+	ret = vfio_device_open(df, NULL, pt_id);
 	if (ret)
 		goto err_unlock_device;
 	mutex_unlock(&device->dev_set->lock);
diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
index 4f82a6fa7c6c..2d8ac65ad7e3 100644
--- a/drivers/vfio/iommufd.c
+++ b/drivers/vfio/iommufd.c
@@ -10,9 +10,17 @@
 MODULE_IMPORT_NS(IOMMUFD);
 MODULE_IMPORT_NS(IOMMUFD_VFIO);
 
-int vfio_iommufd_bind(struct vfio_device *vdev, struct iommufd_ctx *ictx)
+/* @pt_id == NULL impplies detach */
+int vfio_iommufd_attach(struct vfio_device *vdev, u32 *pt_id)
+{
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	return vdev->ops->attach_ioas(vdev, pt_id);
+}
+
+int vfio_iommufd_bind(struct vfio_device *vdev, struct iommufd_ctx *ictx,
+		      u32 *dev_id, u32 *pt_id)
 {
-	u32 ioas_id;
 	u32 device_id;
 	int ret;
 
@@ -29,17 +37,14 @@ int vfio_iommufd_bind(struct vfio_device *vdev, struct iommufd_ctx *ictx)
 	if (ret)
 		return ret;
 
-	ret = iommufd_vfio_compat_ioas_id(ictx, &ioas_id);
-	if (ret)
-		goto err_unbind;
-	ret = vdev->ops->attach_ioas(vdev, &ioas_id);
-	if (ret)
-		goto err_unbind;
+	if (pt_id) {
+		ret = vfio_iommufd_attach(vdev, pt_id);
+		if (ret)
+			goto err_unbind;
+	}
 
-	/*
-	 * The legacy path has no way to return the device id or the selected
-	 * pt_id
-	 */
+	if (dev_id)
+		*dev_id = device_id;
 	return 0;
 
 err_unbind:
@@ -74,14 +79,18 @@ int vfio_iommufd_physical_bind(struct vfio_device *vdev,
 }
 EXPORT_SYMBOL_GPL(vfio_iommufd_physical_bind);
 
+static void __vfio_iommufd_detach(struct vfio_device *vdev)
+{
+	iommufd_device_detach(vdev->iommufd_device);
+	vdev->iommufd_attached = false;
+}
+
 void vfio_iommufd_physical_unbind(struct vfio_device *vdev)
 {
 	lockdep_assert_held(&vdev->dev_set->lock);
 
-	if (vdev->iommufd_attached) {
-		iommufd_device_detach(vdev->iommufd_device);
-		vdev->iommufd_attached = false;
-	}
+	if (vdev->iommufd_attached)
+		__vfio_iommufd_detach(vdev);
 	iommufd_device_unbind(vdev->iommufd_device);
 	vdev->iommufd_device = NULL;
 }
@@ -91,6 +100,20 @@ int vfio_iommufd_physical_attach_ioas(struct vfio_device *vdev, u32 *pt_id)
 {
 	int rc;
 
+	lockdep_assert_held(&vdev->dev_set->lock);
+
+	if (!vdev->iommufd_device)
+		return -EINVAL;
+
+	if (!pt_id) {
+		if (vdev->iommufd_attached)
+			__vfio_iommufd_detach(vdev);
+		return 0;
+	}
+
+	if (vdev->iommufd_attached)
+		return -EBUSY;
+
 	rc = iommufd_device_attach(vdev->iommufd_device, pt_id);
 	if (rc)
 		return rc;
@@ -129,14 +152,18 @@ int vfio_iommufd_emulated_bind(struct vfio_device *vdev,
 }
 EXPORT_SYMBOL_GPL(vfio_iommufd_emulated_bind);
 
+static void __vfio_iommufd_access_destroy(struct vfio_device *vdev)
+{
+	iommufd_access_destroy(vdev->iommufd_access);
+	vdev->iommufd_access = NULL;
+}
+
 void vfio_iommufd_emulated_unbind(struct vfio_device *vdev)
 {
 	lockdep_assert_held(&vdev->dev_set->lock);
 
-	if (vdev->iommufd_access) {
-		iommufd_access_destroy(vdev->iommufd_access);
-		vdev->iommufd_access = NULL;
-	}
+	if (vdev->iommufd_access)
+		__vfio_iommufd_access_destroy(vdev);
 	iommufd_ctx_put(vdev->iommufd_ictx);
 	vdev->iommufd_ictx = NULL;
 }
@@ -148,6 +175,18 @@ int vfio_iommufd_emulated_attach_ioas(struct vfio_device *vdev, u32 *pt_id)
 
 	lockdep_assert_held(&vdev->dev_set->lock);
 
+	if (!vdev->iommufd_ictx)
+		return -EINVAL;
+
+	if (!pt_id) {
+		if (vdev->iommufd_access)
+			__vfio_iommufd_access_destroy(vdev);
+		return 0;
+	}
+
+	if (vdev->iommufd_access)
+		return -EBUSY;
+
 	user = iommufd_access_create(vdev->iommufd_ictx, *pt_id, &vfio_user_ops,
 				     vdev);
 	if (IS_ERR(user))
diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 4f29e3a89f64..c099aa4e7d78 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -25,7 +25,8 @@ struct vfio_device_file {
 
 void vfio_device_put_registration(struct vfio_device *device);
 bool vfio_device_try_get_registration(struct vfio_device *device);
-int vfio_device_open(struct vfio_device_file *df);
+int vfio_device_open(struct vfio_device_file *df,
+		     u32 *dev_id, u32 *pt_id);
 void vfio_device_close(struct vfio_device_file *device);
 
 struct vfio_device_file *
@@ -230,11 +231,14 @@ static inline void vfio_container_cleanup(void)
 #endif
 
 #if IS_ENABLED(CONFIG_IOMMUFD)
-int vfio_iommufd_bind(struct vfio_device *device, struct iommufd_ctx *ictx);
+int vfio_iommufd_bind(struct vfio_device *device, struct iommufd_ctx *ictx,
+		      u32 *dev_id, u32 *pt_id);
 void vfio_iommufd_unbind(struct vfio_device *device);
+int vfio_iommufd_attach(struct vfio_device *vdev, u32 *pt_id);
 #else
 static inline int vfio_iommufd_bind(struct vfio_device *device,
-				    struct iommufd_ctx *ictx)
+				    struct iommufd_ctx *ictx,
+				    u32 *dev_id, u32 *pt_id)
 {
 	return -EOPNOTSUPP;
 }
@@ -242,6 +246,11 @@ static inline int vfio_iommufd_bind(struct vfio_device *device,
 static inline void vfio_iommufd_unbind(struct vfio_device *device)
 {
 }
+
+static inline int vfio_iommufd_attach(struct vfio_device *vdev, u32 *pt_id)
+{
+	return -EOPNOTSUPP;
+}
 #endif
 
 #ifdef CONFIG_VFIO_NOIOMMU
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index bd1d9621af46..304633eee589 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -372,7 +372,8 @@ vfio_allocate_device_file(struct vfio_device *device)
 	return df;
 }
 
-static int vfio_device_first_open(struct vfio_device_file *df)
+static int vfio_device_first_open(struct vfio_device_file *df,
+				  u32 *dev_id, u32 *pt_id)
 {
 	struct vfio_device *device = df->device;
 	struct iommufd_ctx *iommufd = df->iommufd;
@@ -385,7 +386,7 @@ static int vfio_device_first_open(struct vfio_device_file *df)
 		return -ENODEV;
 
 	if (iommufd)
-		ret = vfio_iommufd_bind(device, iommufd);
+		ret = vfio_iommufd_bind(device, iommufd, dev_id, pt_id);
 	else
 		ret = vfio_device_group_use_iommu(device);
 	if (ret)
@@ -427,7 +428,8 @@ static void vfio_device_last_close(struct vfio_device_file *df)
 	module_put(device->dev->driver->owner);
 }
 
-int vfio_device_open(struct vfio_device_file *df)
+int vfio_device_open(struct vfio_device_file *df,
+		     u32 *dev_id, u32 *pt_id)
 {
 	struct vfio_device *device = df->device;
 
@@ -437,7 +439,7 @@ int vfio_device_open(struct vfio_device_file *df)
 	if (device->open_count == 1) {
 		int ret;
 
-		ret = vfio_device_first_open(df);
+		ret = vfio_device_first_open(df, dev_id, pt_id);
 		if (ret) {
 			device->open_count--;
 			return ret;
-- 
2.34.1