[V4,1/3] virtio: get_features() can fail

diff --git a/hw/9pfs/virtio-9p-device.c b/hw/9pfs/virtio-9p-device.c
index 3f4c9e7..93a407c 100644
--- a/hw/9pfs/virtio-9p-device.c
+++ b/hw/9pfs/virtio-9p-device.c
@@ -21,7 +21,8 @@ 
 #include "virtio-9p-coth.h"
 #include "hw/virtio/virtio-access.h"
 
-static uint64_t virtio_9p_get_features(VirtIODevice *vdev, uint64_t features)
+static uint64_t virtio_9p_get_features(VirtIODevice *vdev, uint64_t features,
+                                       Error **errp)
 {
     virtio_add_feature(&features, VIRTIO_9P_MOUNT_TAG);
     return features;
diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c
index 015b9b5..a6cf008 100644
--- a/hw/block/virtio-blk.c
+++ b/hw/block/virtio-blk.c
@@ -722,7 +722,8 @@  static void virtio_blk_set_config(VirtIODevice *vdev, const uint8_t *config)
     aio_context_release(blk_get_aio_context(s->blk));
 }
 
-static uint64_t virtio_blk_get_features(VirtIODevice *vdev, uint64_t features)
+static uint64_t virtio_blk_get_features(VirtIODevice *vdev, uint64_t features,
+                                        Error **errp)
 {
     VirtIOBlock *s = VIRTIO_BLK(vdev);
 
diff --git a/hw/char/virtio-serial-bus.c b/hw/char/virtio-serial-bus.c
index 929e49c..bc56f5d 100644
--- a/hw/char/virtio-serial-bus.c
+++ b/hw/char/virtio-serial-bus.c
@@ -500,7 +500,8 @@  static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
     }
 }
 
-static uint64_t get_features(VirtIODevice *vdev, uint64_t features)
+static uint64_t get_features(VirtIODevice *vdev, uint64_t features,
+                             Error **errp)
 {
     VirtIOSerial *vser;
 
diff --git a/hw/display/virtio-gpu.c b/hw/display/virtio-gpu.c
index 990a26b..a67d927 100644
--- a/hw/display/virtio-gpu.c
+++ b/hw/display/virtio-gpu.c
@@ -89,7 +89,8 @@  static void virtio_gpu_set_config(VirtIODevice *vdev, const uint8_t *config)
     }
 }
 
-static uint64_t virtio_gpu_get_features(VirtIODevice *vdev, uint64_t features)
+static uint64_t virtio_gpu_get_features(VirtIODevice *vdev, uint64_t features,
+                                        Error **errp)
 {
     return features;
 }
diff --git a/hw/input/virtio-input.c b/hw/input/virtio-input.c
index 7f5b8d6..7b25d27 100644
--- a/hw/input/virtio-input.c
+++ b/hw/input/virtio-input.c
@@ -166,7 +166,8 @@  static void virtio_input_set_config(VirtIODevice *vdev,
     virtio_notify_config(vdev);
 }
 
-static uint64_t virtio_input_get_features(VirtIODevice *vdev, uint64_t f)
+static uint64_t virtio_input_get_features(VirtIODevice *vdev, uint64_t f,
+                                          Error **errp)
 {
     return f;
 }
diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index e203058..1510839 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -446,7 +446,8 @@  static void virtio_net_set_queues(VirtIONet *n)
 
 static void virtio_net_set_multiqueue(VirtIONet *n, int multiqueue);
 
-static uint64_t virtio_net_get_features(VirtIODevice *vdev, uint64_t features)
+static uint64_t virtio_net_get_features(VirtIODevice *vdev, uint64_t features,
+                                        Error **errp)
 {
     VirtIONet *n = VIRTIO_NET(vdev);
     NetClientState *nc = qemu_get_queue(n->nic);
diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c
index 52549f8..a69918b 100644
--- a/hw/scsi/vhost-scsi.c
+++ b/hw/scsi/vhost-scsi.c
@@ -153,7 +153,8 @@  static void vhost_scsi_stop(VHostSCSI *s)
 }
 
 static uint64_t vhost_scsi_get_features(VirtIODevice *vdev,
-                                        uint64_t features)
+                                        uint64_t features,
+                                        Error **errp)
 {
     VHostSCSI *s = VHOST_SCSI(vdev);
 
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index d17698d..811c3da 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -629,7 +629,8 @@  static void virtio_scsi_set_config(VirtIODevice *vdev,
 }
 
 static uint64_t virtio_scsi_get_features(VirtIODevice *vdev,
-                                         uint64_t requested_features)
+                                         uint64_t requested_features,
+                                         Error **errp)
 {
     VirtIOSCSI *s = VIRTIO_SCSI(vdev);
 
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 2990f8d..3577b7a 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -310,7 +310,8 @@  static void virtio_balloon_set_config(VirtIODevice *vdev,
     trace_virtio_balloon_set_config(dev->actual, oldactual);
 }
 
-static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f)
+static uint64_t virtio_balloon_get_features(VirtIODevice *vdev, uint64_t f,
+                                            Error **errp)
 {
     VirtIOBalloon *dev = VIRTIO_BALLOON(vdev);
     f |= dev->host_features;
diff --git a/hw/virtio/virtio-bus.c b/hw/virtio/virtio-bus.c
index 3926f7e..febda76 100644
--- a/hw/virtio/virtio-bus.c
+++ b/hw/virtio/virtio-bus.c
@@ -54,7 +54,8 @@  void virtio_bus_device_plugged(VirtIODevice *vdev, Error **errp)
 
     /* Get the features of the plugged device. */
     assert(vdc->get_features != NULL);
-    vdev->host_features = vdc->get_features(vdev, vdev->host_features);
+    vdev->host_features = vdc->get_features(vdev, vdev->host_features,
+                                            errp);
 }
 
 /* Reset the virtio_bus */
diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
index 6e5f022..97d1541 100644
--- a/hw/virtio/virtio-rng.c
+++ b/hw/virtio/virtio-rng.c
@@ -104,7 +104,7 @@  static void handle_input(VirtIODevice *vdev, VirtQueue *vq)
     virtio_rng_process(vrng);
 }
 
-static uint64_t get_features(VirtIODevice *vdev, uint64_t f)
+static uint64_t get_features(VirtIODevice *vdev, uint64_t f, Error **errp)
 {
     return f;
 }
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index ff91711..59f0763 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -101,7 +101,9 @@  typedef struct VirtioDeviceClass {
     /* This is what a VirtioDevice must implement */
     DeviceRealize realize;
     DeviceUnrealize unrealize;
-    uint64_t (*get_features)(VirtIODevice *vdev, uint64_t requested_features);
+    uint64_t (*get_features)(VirtIODevice *vdev,
+                             uint64_t requested_features,
+                             Error **errp);
     uint64_t (*bad_features)(VirtIODevice *vdev);
     void (*set_features)(VirtIODevice *vdev, uint64_t val);
     int (*validate_features)(VirtIODevice *vdev);