2 files changed, 28 insertions, 34 deletions

diff --git a/Documentation/virtual/lguest/lguest.c b/Documentation/virtual/lguest/lguest.c
index e3b9bb7a644..80261d34da3 100644
--- a/Documentation/virtual/lguest/lguest.c
+++ b/Documentation/virtual/lguest/lguest.c
@@ -1095,9 +1095,10 @@ static void update_device_status(struct device *dev)
                 warnx("Device %s configuration FAILED", dev->name);
                 if (dev->running)
                         reset_device(dev);
-        } else if (dev->desc->status & VIRTIO_CONFIG_S_DRIVER_OK) {
-                if (!dev->running)
-                        start_device(dev);
+        } else {
+                if (dev->running)
+                        err(1, "Device %s features finalized twice", dev->name);
+                start_device(dev);
         }
 }
 
@@ -1122,25 +1123,11 @@ static void handle_output(unsigned long addr)
                         return;
                 }
 
-                /*
-                 * Devices *can* be used before status is set to DRIVER_OK.
-                 * The original plan was that they would never do this: they
-                 * would always finish setting up their status bits before
-                 * actually touching the virtqueues.  In practice, we allowed
-                 * them to, and they do (eg. the disk probes for partition
-                 * tables as part of initialization).
-                 *
-                 * If we see this, we start the device: once it's running, we
-                 * expect the device to catch all the notifications.
-                 */
+                /* Devices should not be used before features are finalized. */
                 for (vq = i->vq; vq; vq = vq->next) {
                         if (addr != vq->config.pfn*getpagesize())
                                 continue;
-                        if (i->running)
-                                errx(1, "Notification on running %s", i->name);
-                        /* This just calls create_thread() for each virtqueue */
-                        start_device(i);
-                        return;
+                        errx(1, "Notification on %s before setup!", i->name);
                 }
         }
 
diff --git a/drivers/lguest/lguest_device.c b/drivers/lguest/lguest_device.c
index 69c84a1d88e..5289ffa2e50 100644
--- a/drivers/lguest/lguest_device.c
+++ b/drivers/lguest/lguest_device.c
@@ -109,6 +109,17 @@ static u32 lg_get_features(struct virtio_device *vdev)
 }
 
 /*
+ * To notify on reset or feature finalization, we (ab)use the NOTIFY
+ * hypercall, with the descriptor address of the device.
+ */
+static void status_notify(struct virtio_device *vdev)
+{
+        unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
+
+        hcall(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset, 0, 0, 0);
+}
+
+/*
  * The virtio core takes the features the Host offers, and copies the ones
  * supported by the driver into the vdev->features array.  Once that's all
  * sorted out, this routine is called so we can tell the Host which features we
@@ -135,6 +146,9 @@ static void lg_finalize_features(struct virtio_device *vdev)
                 if (test_bit(i, vdev->features))
                         out_features[i / 8] |= (1 << (i % 8));
         }
+
+        /* Tell Host we've finished with this device's feature negotiation */
+        status_notify(vdev);
 }
 
 /* Once they've found a field, getting a copy of it is easy. */
@@ -168,28 +182,21 @@ static u8 lg_get_status(struct virtio_device *vdev)
         return to_lgdev(vdev)->desc->status;
 }
 
-/*
- * To notify on status updates, we (ab)use the NOTIFY hypercall, with the
- * descriptor address of the device.  A zero status means "reset".
- */
-static void set_status(struct virtio_device *vdev, u8 status)
-{
-        unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
-
-        /* We set the status. */
-        to_lgdev(vdev)->desc->status = status;
-        hcall(LHCALL_NOTIFY, (max_pfn << PAGE_SHIFT) + offset, 0, 0, 0);
-}
-
 static void lg_set_status(struct virtio_device *vdev, u8 status)
 {
         BUG_ON(!status);
-        set_status(vdev, status);
+        to_lgdev(vdev)->desc->status = status;
+
+        /* Tell Host immediately if we failed. */
+        if (status & VIRTIO_CONFIG_S_FAILED)
+                status_notify(vdev);
 }
 
 static void lg_reset(struct virtio_device *vdev)
 {
-        set_status(vdev, 0);
+        /* 0 status means "reset" */
+        to_lgdev(vdev)->desc->status = 0;
+        status_notify(vdev);
 }
 
 /*