[v5,14/20] vfio/ap: Make vfio cdev pre-openable by passing a file handle

Commit Message

Duan, Zhenzhong Nov. 9, 2023, 11:45 a.m. UTC

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 <[e-mail]>
---
 hw/vfio/ap.c | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

Comments

Matthew Rosato Nov. 9, 2023, 10:57 p.m. UTC | #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 <[e-mail]>

Reviewed-by: Matthew Rosato <[e-mail]>

Patch

diff --git a/hw/vfio/ap.c b/hw/vfio/ap.c
index 80629609ae..7a44b41d10 100644
--- a/hw/vfio/ap.c
+++ b/hw/vfio/ap.c
@@ -30,6 +30,7 @@ 
 #include "hw/s390x/ap-bridge.h"
 #include "exec/address-spaces.h"
 #include "qom/object.h"
+#include "monitor/monitor.h"
 
 #define TYPE_VFIO_AP_DEVICE      "vfio-ap"
 
@@ -160,7 +161,10 @@  static void vfio_ap_realize(DeviceState *dev, Error **errp)
     VFIOAPDevice *vapdev = VFIO_AP_DEVICE(dev);
     VFIODevice *vbasedev = &vapdev->vdev;
 
-    vbasedev->name = g_path_get_basename(vbasedev->sysfsdev);
+    if (vfio_device_get_name(vbasedev, errp)) {
+        return;
+    }
+
     vbasedev->ops = &vfio_ap_ops;
     vbasedev->type = VFIO_DEVICE_TYPE_AP;
     vbasedev->dev = dev;
@@ -230,11 +234,36 @@  static const VMStateDescription vfio_ap_vmstate = {
     .unmigratable = 1,
 };
 
+static void vfio_ap_instance_init(Object *obj)
+{
+    VFIOAPDevice *vapdev = VFIO_AP_DEVICE(obj);
+
+    vapdev->vdev.fd = -1;
+}
+
+#ifdef CONFIG_IOMMUFD
+static void vfio_ap_set_fd(Object *obj, const char *str, Error **errp)
+{
+    VFIOAPDevice *vapdev = VFIO_AP_DEVICE(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;
+    }
+    vapdev->vdev.fd = fd;
+}
+#endif
+
 static void vfio_ap_class_init(ObjectClass *klass, void *data)
 {
     DeviceClass *dc = DEVICE_CLASS(klass);
 
     device_class_set_props(dc, vfio_ap_properties);
+#ifdef CONFIG_IOMMUFD
+    object_class_property_add_str(klass, "fd", NULL, vfio_ap_set_fd);
+#endif
     dc->vmsd = &vfio_ap_vmstate;
     dc->desc = "VFIO-based AP device assignment";
     set_bit(DEVICE_CATEGORY_MISC, dc->categories);
@@ -249,6 +278,7 @@  static const TypeInfo vfio_ap_info = {
     .name = TYPE_VFIO_AP_DEVICE,
     .parent = TYPE_AP_DEVICE,
     .instance_size = sizeof(VFIOAPDevice),
+    .instance_init = vfio_ap_instance_init,
     .class_init = vfio_ap_class_init,
 };