2 files changed, 28 insertions, 15 deletions

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index e9851add6f4e..964ad572aaee 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -1056,19 +1056,21 @@ struct vfio_devices {
 static int vfio_pci_get_devs(struct pci_dev *pdev, void *data)
 {
 	struct vfio_devices *devs = data;
-	struct pci_driver *pci_drv = ACCESS_ONCE(pdev->driver);
-
-	if (pci_drv != &vfio_pci_driver)
-		return -EBUSY;
+	struct vfio_device *device;
 
 	if (devs->cur_index == devs->max_index)
 		return -ENOSPC;
 
-	devs->devices[devs->cur_index] = vfio_device_get_from_dev(&pdev->dev);
-	if (!devs->devices[devs->cur_index])
+	device = vfio_device_get_from_dev(&pdev->dev);
+	if (!device)
 		return -EINVAL;
 
-	devs->cur_index++;
+	if (pci_dev_driver(pdev) != &vfio_pci_driver) {
+		vfio_device_put(device);
+		return -EBUSY;
+	}
+
+	devs->devices[devs->cur_index++] = device;
 	return 0;
 }
 
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index e1278fe04b1e..2fb29dfeffbd 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -661,18 +661,29 @@ int vfio_add_group_dev(struct device *dev,
 EXPORT_SYMBOL_GPL(vfio_add_group_dev);
 
 /**
- * Get a reference to the vfio_device for a device that is known to
- * be bound to a vfio driver.  The driver implicitly holds a
- * vfio_device reference between vfio_add_group_dev and
- * vfio_del_group_dev.  We can therefore use drvdata to increment
- * that reference from the struct device.  This additional
- * reference must be released by calling vfio_device_put.
+ * Get a reference to the vfio_device for a device.  Even if the
+ * caller thinks they own the device, they could be racing with a
+ * release call path, so we can't trust drvdata for the shortcut.
+ * Go the long way around, from the iommu_group to the vfio_group
+ * to the vfio_device.
  */
 struct vfio_device *vfio_device_get_from_dev(struct device *dev)
 {
-	struct vfio_device *device = dev_get_drvdata(dev);
+	struct iommu_group *iommu_group;
+	struct vfio_group *group;
+	struct vfio_device *device;
+
+	iommu_group = iommu_group_get(dev);
+	if (!iommu_group)
+		return NULL;
 
-	vfio_device_get(device);
+	group = vfio_group_get_from_iommu(iommu_group);
+	iommu_group_put(iommu_group);
+	if (!group)
+		return NULL;
+
+	device = vfio_group_get_device(group, dev);
+	vfio_group_put(group);
 
 	return device;
 }