@@ -736,7 +736,7 @@ VirtIODevice *virtio_serial_init(DeviceState *dev, uint32_t max_nr_ports)
{
VirtIOSerial *vser;
VirtIODevice *vdev;
- uint32_t i, max_supported_ports;
+ uint32_t i, max_supported_ports, cvq_len;
if (!max_nr_ports)
return NULL;
@@ -769,10 +769,17 @@ VirtIODevice *virtio_serial_init(DeviceState *dev, uint32_t max_nr_ports)
/* Add a queue for guest to host transfers for port 0 (backward compat) */
vser->ovqs[0] = virtio_add_queue(vdev, 128, handle_output);
+ /*
+ * The number of descriptors to use should always be a power of
+ * two. Use the next power of 2 of max_nr_ports to keep the
+ * entries to a minimum.
+ */
+ cvq_len = 1 << qemu_fls(max_nr_ports - 1);
+
/* control queue: host to guest */
- vser->c_ivq = virtio_add_queue(vdev, 16, control_in);
+ vser->c_ivq = virtio_add_queue(vdev, cvq_len, control_in);
/* control queue: guest to host */
- vser->c_ovq = virtio_add_queue(vdev, 16, control_out);
+ vser->c_ovq = virtio_add_queue(vdev, cvq_len, control_out);
for (i = 1; i < vser->bus->max_nr_ports; i++) {
/* Add a per-port queue for host to guest transfers */
The current default of 16 buffers for the control vq is too small for the default max_nr_ports of 32. We can get more entries in there, example when asking the guest to add max. allowed ports. Default to using the minimum required (next power of 2) of the max_nr_ports in use. Signed-off-by: Amit Shah <amit.shah@redhat.com> --- hw/virtio-serial-bus.c | 13 ++++++++++--- 1 files changed, 10 insertions(+), 3 deletions(-)