[Intel-gfx] [PATCH v6 03/24] vfio: Accept vfio device file in the KVM facing kAPI

[Yi Liu]

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

For the kvm set with vfio device file, kvm pointer is stored in struct
vfio_device_file, and use kvm_ref_lock to protect kvm set and kvm
pointer usage within VFIO. This kvm pointer will be set to vfio_device
after device file is bound to iommufd in the cdev path.

Signed-off-by: Yi Liu <yi.l.liu at intel.com>
Reviewed-by: Kevin Tian <kevin.tian at intel.com>
Reviewed-by: Jason Gunthorpe <jgg at nvidia.com>
Tested-by: Terrence Xu <terrence.xu at intel.com>
Tested-by: Nicolin Chen <nicolinc at nvidia.com>
Tested-by: Matthew Rosato <mjrosato at linux.ibm.com>
---
 drivers/vfio/vfio.h      |  2 ++
 drivers/vfio/vfio_main.c | 42 +++++++++++++++++++++++++++++++++++++---
 2 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/drivers/vfio/vfio.h b/drivers/vfio/vfio.h
index b1e327a85a32..69e1a0692b06 100644
--- a/drivers/vfio/vfio.h
+++ b/drivers/vfio/vfio.h
@@ -18,6 +18,8 @@ struct vfio_container;
 
 struct vfio_device_file {
 	struct vfio_device *device;
+	spinlock_t kvm_ref_lock; /* protect kvm field */
+	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 edadfac9be49..03d5b2979f79 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -414,6 +414,7 @@ vfio_allocate_device_file(struct vfio_device *device)
 		return ERR_PTR(-ENOMEM);
 
 	df->device = device;
+	spin_lock_init(&df->kvm_ref_lock);
 
 	return df;
 }
@@ -1175,13 +1176,23 @@ 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 valid vfio file
  * @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);
 
@@ -1196,15 +1207,36 @@ 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 device_iommu_capable(device->dev,
+					    IOMMU_CAP_ENFORCE_CACHE_COHERENCY);
+
 	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;
+
+	/*
+	 * The kvm is first recorded in the vfio_device_file, and will
+	 * be propagated to vfio_device::kvm when the file is bound to
+	 * iommufd successfully in the vfio device cdev path.
+	 */
+	spin_lock(&df->kvm_ref_lock);
+	df->kvm = kvm;
+	spin_unlock(&df->kvm_ref_lock);
+}
+
 /**
  * vfio_file_set_kvm - Link a kvm with VFIO drivers
  * @file: VFIO group file or VFIO device file
@@ -1213,10 +1245,14 @@ 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);
 
-- 
2.34.1