Windows drivers from 22 Jan 2013 and older fail when config size != 32,
which was the size before max_virtqueue_pairs was added.
Force config size to a value these drivers expect to avoid
breakage unless we really need max_virtqueue_pairs.
Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
---
hw/virtio-net.c | 15 ++++++++++++---
hw/virtio-net.h | 6 +++++-
2 files changed, 17 insertions(+), 4 deletions(-)
diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 510a0f6..2464cd5 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -1287,9 +1287,18 @@ VirtIODevice *virtio_net_init(DeviceState *dev, NICConf
*conf,
{
VirtIONet *n;
int i;
-
- n = (VirtIONet *)virtio_common_init("virtio-net", VIRTIO_ID_NET,
- sizeof(struct virtio_net_config),
+ size_t config_size;
+
+ /*
+ * Windows drivers from 22 Jan 2013 and older fail when config size != 32,
+ * which was the size before max_virtqueue_pairs was added.
+ * Force config size to a value these drivers expect to avoid
+ * breakage unless we really need max_virtqueue_pairs.
+ */
+ config_size = conf->queues > 1 ? sizeof(struct virtio_net_config) :
+ offsetof(struct virtio_net_config, max_virtqueue_pairs);
+
+ n = (VirtIONet *)virtio_common_init("virtio-net", VIRTIO_ID_NET,
config_size,
sizeof(VirtIONet));
n->vdev.get_config = virtio_net_get_config;
diff --git a/hw/virtio-net.h b/hw/virtio-net.h
index 414365d..799b2ca 100644
--- a/hw/virtio-net.h
+++ b/hw/virtio-net.h
@@ -75,7 +75,11 @@ struct virtio_net_config
uint8_t mac[ETH_ALEN];
/* See VIRTIO_NET_F_STATUS and VIRTIO_NET_S_* above */
uint16_t status;
- /* Max virtqueue pairs supported by the device */
+ /*
+ * Fields below need special handling because of driver bugs.
+ * See virtio_net_init.
+ * Max virtqueue pairs supported by the device.
+ */
uint16_t max_virtqueue_pairs;
} QEMU_PACKED;
--
MST
