[Qemu-devel] [PATCHv2] virtio-net: remove mq feature flag

[Michael S. Tsirkin]

mq flag is not needed: we can look at the number of queues and set
the flag accordingly.
Removing this feature removes ambiguity (what does it mean to have
queues=2 with mq=off?), and simplifies compatibility hacks.
work-around for buggy windows
guests.

Signed-off-by: Michael S. Tsirkin <address@hidden>
---
 hw/pc_piix.c    |  4 ----
 hw/virtio-net.c |  8 +++++++-
 hw/virtio-net.h | 15 ++++++++++++---
 3 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/hw/pc_piix.c b/hw/pc_piix.c
index 0af436c..ba09714 100644
--- a/hw/pc_piix.c
+++ b/hw/pc_piix.c
@@ -313,10 +313,6 @@ static QEMUMachine pc_i440fx_machine_v1_4 = {
             .driver   = "virtio-net-pci",\
             .property = "ctrl_mac_addr",\
             .value    = "off",      \
-        },{ \
-            .driver   = "virtio-net-pci", \
-            .property = "mq", \
-            .value    = "off", \
         }
 
 static QEMUMachine pc_machine_v1_3 = {
diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index e37358a..8db1787 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -346,6 +346,10 @@ static uint32_t virtio_net_get_features(VirtIODevice 
*vdev, uint32_t features)
 
     features |= (1 << VIRTIO_NET_F_MAC);
 
+    if (n->max_queues > 1) {
+        features |= (0x1 << VIRTIO_NET_F_MQ);
+    }
+
     if (!peer_has_vnet_hdr(n)) {
         features &= ~(0x1 << VIRTIO_NET_F_CSUM);
         features &= ~(0x1 << VIRTIO_NET_F_HOST_TSO4);
@@ -1285,7 +1289,9 @@ VirtIODevice *virtio_net_init(DeviceState *dev, NICConf 
*conf,
     int i;
 
     n = (VirtIONet *)virtio_common_init("virtio-net", VIRTIO_ID_NET,
-                                        sizeof(struct virtio_net_config),
+                                        conf->queues > 1 ?
+                                            sizeof(struct virtio_net_config) :
+                                            sizeof(struct 
virtio_net_config_compat),
                                         sizeof(VirtIONet));
 
     n->vdev.get_config = virtio_net_get_config;
diff --git a/hw/virtio-net.h b/hw/virtio-net.h
index f5fea6e..b1f7647 100644
--- a/hw/virtio-net.h
+++ b/hw/virtio-net.h
@@ -69,6 +69,17 @@ typedef struct virtio_net_conf
 /* Maximum packet size we can receive from tap device: header + 64k */
 #define VIRTIO_NET_MAX_BUFSIZE (sizeof(struct virtio_net_hdr) + (64 << 10))
 
+/*
+ * Windows drivers from 22 Jan 2013 and older fail when config size != 32.
+ */
+struct virtio_net_config_compat
+{
+    /* The config defining mac address ($ETH_ALEN bytes) */
+    uint8_t mac[ETH_ALEN];
+    /* See VIRTIO_NET_F_STATUS and VIRTIO_NET_S_* above */
+    uint16_t status;
+} QEMU_PACKED;
+
 struct virtio_net_config
 {
     /* The config defining mac address ($ETH_ALEN bytes) */
@@ -190,7 +201,5 @@ struct virtio_net_ctrl_mq {
         DEFINE_PROP_BIT("ctrl_rx", _state, _field, VIRTIO_NET_F_CTRL_RX, 
true), \
         DEFINE_PROP_BIT("ctrl_vlan", _state, _field, VIRTIO_NET_F_CTRL_VLAN, 
true), \
         DEFINE_PROP_BIT("ctrl_rx_extra", _state, _field, 
VIRTIO_NET_F_CTRL_RX_EXTRA, true), \
-        DEFINE_PROP_BIT("ctrl_mac_addr", _state, _field, 
VIRTIO_NET_F_CTRL_MAC_ADDR, true), \
-        DEFINE_PROP_BIT("mq", _state, _field, VIRTIO_NET_F_MQ, true)
-
+        DEFINE_PROP_BIT("ctrl_mac_addr", _state, _field, 
VIRTIO_NET_F_CTRL_MAC_ADDR, true)
 #endif
-- 
MST