[Qemu-stable] [PATCH 95/99] virtio-rng: process pending requests on DRIVER_OK

[Michael Roth]

From: Pankaj Gupta <address@hidden>

virtio-rng device causes old guest kernels(2.6.32) to hang on latest qemu.
The driver attempts to read from the virtio-rng device too early in it's
initialization. Qemu detects guest is not ready and returns, resulting in
hang.

To fix handle pending requests when guest is running and driver status is
set to 'VIRTIO_CONFIG_S_DRIVER_OK'.

CC: address@hidden
Reported-by: Sergio lopez <address@hidden>
Signed-off-by: Stefan Hajnoczi <address@hidden>
Signed-off-by: Pankaj Gupta <address@hidden>
Reviewed-by: Michael S. Tsirkin <address@hidden>
Signed-off-by: Michael S. Tsirkin <address@hidden>
(cherry picked from commit 5d9c9ea22ab4f3b3ee497523e34b6f4d3281f62d)
Signed-off-by: Michael Roth <address@hidden>
---
 hw/virtio/virtio-rng.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
index 289bbcac03..855f1b41d1 100644
--- a/hw/virtio/virtio-rng.c
+++ b/hw/virtio/virtio-rng.c
@@ -156,6 +156,19 @@ static void check_rate_limit(void *opaque)
     vrng->activate_timer = true;
 }
 
+static void virtio_rng_set_status(VirtIODevice *vdev, uint8_t status)
+{
+    VirtIORNG *vrng = VIRTIO_RNG(vdev);
+
+    if (!vdev->vm_running) {
+        return;
+    }
+    vdev->status = status;
+
+    /* Something changed, try to process buffers */
+    virtio_rng_process(vrng);
+}
+
 static void virtio_rng_device_realize(DeviceState *dev, Error **errp)
 {
     VirtIODevice *vdev = VIRTIO_DEVICE(dev);
@@ -261,6 +274,7 @@ static void virtio_rng_class_init(ObjectClass *klass, void 
*data)
     vdc->realize = virtio_rng_device_realize;
     vdc->unrealize = virtio_rng_device_unrealize;
     vdc->get_features = get_features;
+    vdc->set_status = virtio_rng_set_status;
 }
 
 static const TypeInfo virtio_rng_info = {
-- 
2.17.1