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From 28648492db9520d5914ea20eaa8425aae3d1627d Mon Sep 17 00:00:00 2001
From: Pankaj Gupta <pagupta@redhat.com>
Date: Fri, 13 Jul 2018 12:52:28 +0200
Subject: [PATCH 216/268] virtio-rng: process pending requests on DRIVER_OK

RH-Author: Pankaj Gupta <pagupta@redhat.com>
Message-id: <20180713125228.14458-1-pagupta@redhat.com>
Patchwork-id: 81347
O-Subject: [RHEL7.6 qemu-kvm-rhev PATCH] virtio-rng: process pending requests on DRIVER_OK
Bugzilla: 1576743
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>

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: qemu-stable@nongnu.org
Reported-by: Sergio lopez <slopezpa@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit 5d9c9ea22ab4f3b3ee497523e34b6f4d3281f62d)
Signed-off-by: Pankaj Gupta <pagupta@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 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 289bbca..855f1b4 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 = {
-- 
1.8.3.1