virtio-serial: Check if more max_ports specified than we can handle

Currently virtio-serial supports a maximum of 31 ports. Specifying the
'max_ports' parameter to be > 31 on the cmd line causes badness.

Ensure we initialise virtio-serial only if max_ports is within the
supported range.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

diff --git a/hw/virtio-serial-bus.c b/hw/virtio-serial-bus.c
index 8e611c0..0586b89 100644 (file)
--- a/hw/virtio-serial-bus.c
+++ b/hw/virtio-serial-bus.c
@@ -734,11 +734,19 @@ VirtIODevice *virtio_serial_init(DeviceState *dev, uint32_t max_nr_ports)
 {
     VirtIOSerial *vser;
     VirtIODevice *vdev;
-    uint32_t i;
+    uint32_t i, max_supported_ports;
 
     if (!max_nr_ports)
         return NULL;
 
+    /* Each port takes 2 queues, and one pair is for the control queue */
+    max_supported_ports = VIRTIO_PCI_QUEUE_MAX / 2 - 1;
+
+    if (max_nr_ports > max_supported_ports) {
+        error_report("maximum ports supported: %u", max_supported_ports);
+        return NULL;
+    }
+
     vdev = virtio_common_init("virtio-serial", VIRTIO_ID_CONSOLE,
                               sizeof(struct virtio_console_config),
                               sizeof(VirtIOSerial));