On Sun, Feb 03, 2013 at 04:57:38PM -0600, Anthony Liguori wrote:
> "Michael S. Tsirkin" <m...@redhat.com> writes:
>
> > On Sun, Feb 03, 2013 at 03:09:39PM -0600, Anthony Liguori wrote:
> >> Michael Tokarev <m...@tls.msk.ru> writes:
> >>
> >> > 03.02.2013 17:23, Yan Vugenfirer wrote:
> >> >
> >> >>> If it helps, mq changes the config size from 8 to 16 bytes. If the
> >> >>> driver was making an assumption about an 8-byte config size, that's
> >> >>> likely what the problem is.
> >> >>>
> >> >> That's exactly the problem.
> >> >
> >> > So what do we do? It isn't nice to break existing setups.
> >> > Maybe mq can be disabled by default (together with Antony's
> >> > patch) until fixed drivers will be more widely available?
> >>
> >> I've got a patch that does exactly like this. It's pretty ugly though
> >> because of the relationship between virtio-pci and virtio-net. I'm
> >> going to try to see if I can find a cleaner way to do it on Monday.
> >>
> >> I'm also contemplating just disabling mq by default. Since a special
> >> command line is needed to enable it anyway (on the backend), having to
> >> specify mq=on for the device doesn't seem so bad.
> >
> >
> > It's after midnight here so didn't test yet, but wouldn't the following
> > achieve this in a way that is a bit cleaner?
> >
> > Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
> >
> >
> > diff --git a/hw/virtio-net.c b/hw/virtio-net.c
> > index 5699f5e..3342a76 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);
> > + }
> > +
>
> This is too late because the config size has already been set.
>
> > if (!peer_has_vnet_hdr(n)) {
> > features &= ~(0x1 << VIRTIO_NET_F_CSUM);
> > features &= ~(0x1 << VIRTIO_NET_F_HOST_TSO4);
> > @@ -1284,7 +1288,9 @@ 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));
>
> This makes me a bit nervous. It relies on setting the config size to
> one thing before we've masked a feature.
>
> What do you think about just defaulting mq=off? The more I think about
> it, the nicer of an option that is.
>
> I'm not a huge fan of automagically changing the value of a feature bit
> so I think defaulting it off is a bit more straight forward.
>
> We can certainly revisit for 1.5+.
>
> Regards,
>
> Anthony Liguori
Thinking about it some more, we have the queues option so
adding an mq option as well is not useful.
Let's clear it unless # of queues is set?
What do you think about the below?
This time tested with an sq guest but not an mq guest yet.
Signed-off-by: Michael S. Tsirkin <m...@redhat.com>
---
diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 5699f5e..b8c8439 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);
@@ -1284,7 +1288,9 @@ 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 1d5c721..19f63cf 100644
--- a/hw/virtio-net.h
+++ b/hw/virtio-net.h
@@ -69,6 +69,14 @@ 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))
+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) */
@@ -190,6 +199,5 @@ 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
