This gives management tools like libvirt a chance to open the vfio
cdev with privilege and pass FD to qemu. This way qemu never needs
to have privilege to open a VFIO or iommu cdev node.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
---
 hw/vfio/ccw.c | 34 +++++++++++++++++++++++++++++++---
 1 file changed, 31 insertions(+), 3 deletions(-)

diff --git a/hw/vfio/ccw.c b/hw/vfio/ccw.c
index d2d58bb677..a566aad404 100644
--- a/hw/vfio/ccw.c
+++ b/hw/vfio/ccw.c
@@ -31,6 +31,7 @@
 #include "qemu/error-report.h"
 #include "qemu/main-loop.h"
 #include "qemu/module.h"
+#include "monitor/monitor.h"
 
 struct VFIOCCWDevice {
     S390CCWDevice cdev;
@@ -590,11 +591,12 @@ static void vfio_ccw_realize(DeviceState *dev, Error **errp)
         }
     }
 
+    if (vfio_device_get_name(vbasedev, errp)) {
+        return;
+    }
+
     vbasedev->ops = &vfio_ccw_ops;
     vbasedev->type = VFIO_DEVICE_TYPE_CCW;
-    vbasedev->name = g_strdup_printf("%x.%x.%04x", vcdev->cdev.hostid.cssid,
-                           vcdev->cdev.hostid.ssid,
-                           vcdev->cdev.hostid.devid);
     vbasedev->dev = dev;
 
     /*
@@ -691,12 +693,37 @@ static const VMStateDescription vfio_ccw_vmstate = {
     .unmigratable = 1,
 };
 
+static void vfio_ccw_instance_init(Object *obj)
+{
+    VFIOCCWDevice *vcdev = VFIO_CCW(obj);
+
+    vcdev->vdev.fd = -1;
+}
+
+#ifdef CONFIG_IOMMUFD
+static void vfio_ccw_set_fd(Object *obj, const char *str, Error **errp)
+{
+    VFIOCCWDevice *vcdev = VFIO_CCW(obj);
+    int fd = -1;
+
+    fd = monitor_fd_param(monitor_cur(), str, errp);
+    if (fd == -1) {
+        error_prepend(errp, "Could not parse remote object fd %s:", str);
+        return;
+    }
+    vcdev->vdev.fd = fd;
+}
+#endif
+
 static void vfio_ccw_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
     S390CCWDeviceClass *cdc = S390_CCW_DEVICE_CLASS(klass);
 
     device_class_set_props(dc, vfio_ccw_properties);
+#ifdef CONFIG_IOMMUFD
+    object_class_property_add_str(klass, "fd", NULL, vfio_ccw_set_fd);
+#endif
     dc->vmsd = &vfio_ccw_vmstate;
     dc->desc = "VFIO-based subchannel assignment";
     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
@@ -714,6 +741,7 @@ static const TypeInfo vfio_ccw_info = {
     .name = TYPE_VFIO_CCW,
     .parent = TYPE_S390_CCW,
     .instance_size = sizeof(VFIOCCWDevice),
+    .instance_init = vfio_ccw_instance_init,
     .class_init = vfio_ccw_class_init,
 };
 
-- 
2.34.1

On 11/9/23 6:45 AM, Zhenzhong Duan wrote:
> This gives management tools like libvirt a chance to open the vfio
> cdev with privilege and pass FD to qemu. This way qemu never needs
> to have privilege to open a VFIO or iommu cdev node.
> 
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>

Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>