[RFC 03/12] vfio: Accept vfio device file in the driver facing kAPI

[Yi Liu <yi.l.liu@xxxxxxxxx>]

This makes the vfio file kAPIs to accepte vfio device files, also a
preparation for vfio device cdev support.

Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
---
 drivers/vfio/vfio.h      |  1 +
 drivers/vfio/vfio_main.c | 64 +++++++++++++++++++++++++++++++++++++---
 2 files changed, 61 insertions(+), 4 deletions(-)

diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index 69d0fd7e351e..f0e411995997 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -18,6 +18,7 @@ struct vfio_container;
 
 struct vfio_device_file {
 	struct vfio_device *device;
+	struct kvm *kvm;
 };
 
 void vfio_device_put_registration(struct vfio_device *device);
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index 7d13c5f0bfab..481502a6964a 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -1029,16 +1029,40 @@ const struct file_operations vfio_device_fops = {
 	.mmap		= vfio_device_fops_mmap,
 };
 
+static struct vfio_device *vfio_device_from_file(struct file *file)
+{
+	struct vfio_device_file *df = file->private_data;
+
+	if (file->f_op != &vfio_device_fops)
+		return NULL;
+	return df->device;
+}
+
 /**
  * vfio_file_is_valid - True if the file is usable with VFIO aPIS
  * @file: VFIO group file or VFIO device file
  */
 bool vfio_file_is_valid(struct file *file)
 {
-	return vfio_group_from_file(file);
+	return vfio_group_from_file(file) ||
+	       vfio_device_from_file(file);
 }
 EXPORT_SYMBOL_GPL(vfio_file_is_valid);
 
+static bool vfio_device_enforced_coherent(struct vfio_device *device)
+{
+	bool ret;
+
+	if (!vfio_device_try_get_registration(device))
+		return true;
+
+	ret = device_iommu_capable(device->dev,
+				   IOMMU_CAP_ENFORCE_CACHE_COHERENCY);
+
+	vfio_device_put_registration(device);
+	return ret;
+}
+
 /**
  * vfio_file_enforced_coherent - True if the DMA associated with the VFIO file
  *        is always CPU cache coherent
@@ -1050,15 +1074,36 @@ EXPORT_SYMBOL_GPL(vfio_file_is_valid);
  */
 bool vfio_file_enforced_coherent(struct file *file)
 {
-	struct vfio_group *group = vfio_group_from_file(file);
+	struct vfio_group *group;
+	struct vfio_device *device;
 
+	group = vfio_group_from_file(file);
 	if (group)
 		return vfio_group_enforced_coherent(group);
 
+	device = vfio_device_from_file(file);
+	if (device)
+		return vfio_device_enforced_coherent(device);
+
 	return true;
 }
 EXPORT_SYMBOL_GPL(vfio_file_enforced_coherent);
 
+static void vfio_device_file_set_kvm(struct file *file, struct kvm *kvm)
+{
+	struct vfio_device_file *df = file->private_data;
+	struct vfio_device *device = df->device;
+
+	/*
+	 * The kvm is first recorded in the df, and will be propagated
+	 * to vfio_device::kvm when the file binds iommufd successfully in
+	 * the vfio device cdev path.
+	 */
+	mutex_lock(&device->dev_set->lock);
+	df->kvm = kvm;
+	mutex_unlock(&device->dev_set->lock);
+}
+
 /**
  * vfio_file_set_kvm - Link a kvm with VFIO drivers
  * @file: VFIO group file or device file
@@ -1067,10 +1112,14 @@ EXPORT_SYMBOL_GPL(vfio_file_enforced_coherent);
  */
 void vfio_file_set_kvm(struct file *file, struct kvm *kvm)
 {
-	struct vfio_group *group = vfio_group_from_file(file);
+	struct vfio_group *group;
 
+	group = vfio_group_from_file(file);
 	if (group)
 		vfio_group_set_kvm(group, kvm);
+
+	if (vfio_device_from_file(file))
+		vfio_device_file_set_kvm(file, kvm);
 }
 EXPORT_SYMBOL_GPL(vfio_file_set_kvm);
 
@@ -1083,10 +1132,17 @@ EXPORT_SYMBOL_GPL(vfio_file_set_kvm);
  */
 bool vfio_file_has_dev(struct file *file, struct vfio_device *device)
 {
-	struct vfio_group *group = vfio_group_from_file(file);
+	struct vfio_group *group;
+	struct vfio_device *vdev;
 
+	group = vfio_group_from_file(file);
 	if (group)
 		return vfio_group_has_dev(group, device);
+
+	vdev = vfio_device_from_file(file);
+	if (device)
+		return vdev == device;
+
 	return false;
 }
 EXPORT_SYMBOL_GPL(vfio_file_has_dev);
-- 
2.34.1