vfio/pci: Extend VFIO_DEVICE_GET_PCI_HOT_RESET_INFO for vfio device cdev

This allows VFIO_DEVICE_GET_PCI_HOT_RESET_INFO ioctl use the iommufd_ctx
of the cdev device to check the ownership of the other affected devices.

When VFIO_DEVICE_GET_PCI_HOT_RESET_INFO is called on an IOMMUFD managed
device, the new flag VFIO_PCI_HOT_RESET_FLAG_DEV_ID is reported to indicate
the values returned are IOMMUFD devids rather than group IDs as used when
accessing vfio devices through the conventional vfio group interface.
Additionally the flag VFIO_PCI_HOT_RESET_FLAG_DEV_ID_OWNED will be reported
in this mode if all of the devices affected by the hot-reset are owned by
either virtue of being directly bound to the same iommufd context as the
calling device, or implicitly owned via a shared IOMMU group.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Suggested-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Yanting Jiang <yanting.jiang@intel.com>
Tested-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Link: https://lore.kernel.org/r/20230718105542.4138-9-yi.l.liu@intel.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

1 files changed, 44 insertions, 0 deletions

diff --git a/drivers/vfio/iommufd.c b/drivers/vfio/iommufd.c
index 88b00c501015..afda47ee9663 100644
--- a/drivers/vfio/iommufd.c
+++ b/drivers/vfio/iommufd.c
@@ -66,6 +66,50 @@ void vfio_iommufd_unbind(struct vfio_device *vdev)
 		vdev->ops->unbind_iommufd(vdev);
 }
 
+struct iommufd_ctx *vfio_iommufd_device_ictx(struct vfio_device *vdev)
+{
+	if (vdev->iommufd_device)
+		return iommufd_device_to_ictx(vdev->iommufd_device);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_device_ictx);
+
+static int vfio_iommufd_device_id(struct vfio_device *vdev)
+{
+	if (vdev->iommufd_device)
+		return iommufd_device_to_id(vdev->iommufd_device);
+	return -EINVAL;
+}
+
+/*
+ * Return devid for a device.
+ *  valid ID for the device that is owned by the ictx
+ *  -ENOENT = device is owned but there is no ID
+ *  -ENODEV or other error = device is not owned
+ */
+int vfio_iommufd_get_dev_id(struct vfio_device *vdev, struct iommufd_ctx *ictx)
+{
+	struct iommu_group *group;
+	int devid;
+
+	if (vfio_iommufd_device_ictx(vdev) == ictx)
+		return vfio_iommufd_device_id(vdev);
+
+	group = iommu_group_get(vdev->dev);
+	if (!group)
+		return -ENODEV;
+
+	if (iommufd_ctx_has_group(ictx, group))
+		devid = -ENOENT;
+	else
+		devid = -ENODEV;
+
+	iommu_group_put(group);
+
+	return devid;
+}
+EXPORT_SYMBOL_GPL(vfio_iommufd_get_dev_id);
+
 /*
  * The physical standard ops mean that the iommufd_device is bound to the
  * physical device vdev->dev that was provided to vfio_init_group_dev(). Drivers