[Qemu-devel] [PATCH 06/12] virtio-ccw: Check the number of vqs in CCW_CMD_SET_IND

[Cornelia Huck]

From: Halil Pasic <address@hidden>

We cannot support more than 64 virtqueues with the 64 bits provided by
classic indicators. If a driver tries to setup classic indicators
(which it is free to do even for virtio-1 devices) for a device with
more than 64 virtqueues, we should reject the attempt so that the
driver does not end up with an unusable device.

This is in preparation for bumping the number of supported virtqueues
on the ccw transport.

Signed-off-by: Halil Pasic <address@hidden>
Reviewed-by: Cornelia Huck <address@hidden>
Reviewed-by: Christian Borntraeger <address@hidden>
Signed-off-by: Cornelia Huck <address@hidden>
---
 hw/s390x/virtio-ccw.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/hw/s390x/virtio-ccw.c b/hw/s390x/virtio-ccw.c
index 613d8c6615..771411ea3c 100644
--- a/hw/s390x/virtio-ccw.c
+++ b/hw/s390x/virtio-ccw.c
@@ -35,6 +35,8 @@
 #include "trace.h"
 #include "hw/s390x/css-bridge.h"
 
+#define NR_CLASSIC_INDICATOR_BITS 64
+
 static void virtio_ccw_bus_new(VirtioBusState *bus, size_t bus_size,
                                VirtioCcwDevice *dev);
 
@@ -509,6 +511,11 @@ static int virtio_ccw_cb(SubchDev *sch, CCW1 ccw)
             ret = -ENOSYS;
             break;
         }
+        if (virtio_get_num_queues(vdev) > NR_CLASSIC_INDICATOR_BITS) {
+            /* More queues than indicator bits --> trigger a reject */
+            ret = -ENOSYS;
+            break;
+        }
         if (!ccw.cda) {
             ret = -EFAULT;
         } else {
-- 
2.11.0