Sridhar Samudrala
2017-Dec-19 00:40 UTC
[RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
This patch enables virtio to switch over to a VF datapath when a VF netdev
is present with the same MAC address. It allows live migration of a VM
with a direct attached VF without the need to setup a bond/team between a
VF and virtio net device in the guest.
The hypervisor needs to unplug the VF device from the guest on the source
host and reset the MAC filter of the VF to initiate failover of datapath to
virtio before starting the migration. After the migration is completed, the
destination hypervisor sets the MAC filter on the VF and plugs it back to
the guest to switch over to VF datapath.
It is entirely based on netvsc implementation and it should be possible to
make this code generic and move it to a common location that can be shared
by netvsc and virtio.
Also, i think we should make this a negotiated feature that is off by
default via a new feature bit.
This patch is based on the discussion initiated by Jesse on this thread.
https://marc.info/?l=linux-virtualization&m=151189725224231&w=2
Signed-off-by: Sridhar Samudrala <sridhar.samudrala at intel.com>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg at intel.com>
---
drivers/net/virtio_net.c | 341 ++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 339 insertions(+), 2 deletions(-)
diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 559b215c0169..a34c717bb15b 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -31,6 +31,8 @@
#include <linux/average.h>
#include <linux/filter.h>
#include <net/route.h>
+#include <linux/netdevice.h>
+#include <linux/netpoll.h>
static int napi_weight = NAPI_POLL_WEIGHT;
module_param(napi_weight, int, 0444);
@@ -56,6 +58,8 @@ module_param(napi_tx, bool, 0644);
*/
DECLARE_EWMA(pkt_len, 0, 64)
+#define VF_TAKEOVER_INT (HZ / 10)
+
#define VIRTNET_DRIVER_VERSION "1.0.0"
static const unsigned long guest_offloads[] = {
@@ -117,6 +121,15 @@ struct receive_queue {
char name[40];
};
+struct virtnet_vf_pcpu_stats {
+ u64 rx_packets;
+ u64 rx_bytes;
+ u64 tx_packets;
+ u64 tx_bytes;
+ struct u64_stats_sync syncp;
+ u32 tx_dropped;
+};
+
struct virtnet_info {
struct virtio_device *vdev;
struct virtqueue *cvq;
@@ -179,6 +192,11 @@ struct virtnet_info {
u32 speed;
unsigned long guest_offloads;
+
+ /* State to manage the associated VF interface. */
+ struct net_device __rcu *vf_netdev;
+ struct virtnet_vf_pcpu_stats __percpu *vf_stats;
+ struct delayed_work vf_takeover;
};
struct padded_vnet_hdr {
@@ -1300,16 +1318,51 @@ static int xmit_skb(struct send_queue *sq, struct
sk_buff *skb)
return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, skb, GFP_ATOMIC);
}
+/* Send skb on the slave VF device. */
+static int virtnet_vf_xmit(struct net_device *dev, struct net_device
*vf_netdev,
+ struct sk_buff *skb)
+{
+ struct virtnet_info *vi = netdev_priv(dev);
+ unsigned int len = skb->len;
+ int rc;
+
+ skb->dev = vf_netdev;
+ skb->queue_mapping = qdisc_skb_cb(skb)->slave_dev_queue_mapping;
+
+ rc = dev_queue_xmit(skb);
+ if (likely(rc == NET_XMIT_SUCCESS || rc == NET_XMIT_CN)) {
+ struct virtnet_vf_pcpu_stats *pcpu_stats
+ = this_cpu_ptr(vi->vf_stats);
+
+ u64_stats_update_begin(&pcpu_stats->syncp);
+ pcpu_stats->tx_packets++;
+ pcpu_stats->tx_bytes += len;
+ u64_stats_update_end(&pcpu_stats->syncp);
+ } else {
+ this_cpu_inc(vi->vf_stats->tx_dropped);
+ }
+
+ return rc;
+}
+
static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev)
{
struct virtnet_info *vi = netdev_priv(dev);
int qnum = skb_get_queue_mapping(skb);
struct send_queue *sq = &vi->sq[qnum];
+ struct net_device *vf_netdev;
int err;
struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum);
bool kick = !skb->xmit_more;
bool use_napi = sq->napi.weight;
+ /* if VF is present and up then redirect packets
+ * called with rcu_read_lock_bh
+ */
+ vf_netdev = rcu_dereference_bh(vi->vf_netdev);
+ if (vf_netdev && netif_running(vf_netdev) &&
!netpoll_tx_running(dev))
+ return virtnet_vf_xmit(dev, vf_netdev, skb);
+
/* Free up any pending old buffers before queueing new ones. */
free_old_xmit_skbs(sq);
@@ -1456,10 +1509,41 @@ static int virtnet_set_mac_address(struct net_device
*dev, void *p)
return ret;
}
+static void virtnet_get_vf_stats(struct net_device *dev,
+ struct virtnet_vf_pcpu_stats *tot)
+{
+ struct virtnet_info *vi = netdev_priv(dev);
+ int i;
+
+ memset(tot, 0, sizeof(*tot));
+
+ for_each_possible_cpu(i) {
+ const struct virtnet_vf_pcpu_stats *stats
+ = per_cpu_ptr(vi->vf_stats, i);
+ u64 rx_packets, rx_bytes, tx_packets, tx_bytes;
+ unsigned int start;
+
+ do {
+ start = u64_stats_fetch_begin_irq(&stats->syncp);
+ rx_packets = stats->rx_packets;
+ tx_packets = stats->tx_packets;
+ rx_bytes = stats->rx_bytes;
+ tx_bytes = stats->tx_bytes;
+ } while (u64_stats_fetch_retry_irq(&stats->syncp, start));
+
+ tot->rx_packets += rx_packets;
+ tot->tx_packets += tx_packets;
+ tot->rx_bytes += rx_bytes;
+ tot->tx_bytes += tx_bytes;
+ tot->tx_dropped += stats->tx_dropped;
+ }
+}
+
static void virtnet_stats(struct net_device *dev,
struct rtnl_link_stats64 *tot)
{
struct virtnet_info *vi = netdev_priv(dev);
+ struct virtnet_vf_pcpu_stats vf_stats;
int cpu;
unsigned int start;
@@ -1490,6 +1574,13 @@ static void virtnet_stats(struct net_device *dev,
tot->rx_dropped = dev->stats.rx_dropped;
tot->rx_length_errors = dev->stats.rx_length_errors;
tot->rx_frame_errors = dev->stats.rx_frame_errors;
+
+ virtnet_get_vf_stats(dev, &vf_stats);
+ tot->rx_packets += vf_stats.rx_packets;
+ tot->tx_packets += vf_stats.tx_packets;
+ tot->rx_bytes += vf_stats.rx_bytes;
+ tot->tx_bytes += vf_stats.tx_bytes;
+ tot->tx_dropped += vf_stats.tx_dropped;
}
#ifdef CONFIG_NET_POLL_CONTROLLER
@@ -2508,6 +2599,47 @@ static int virtnet_validate(struct virtio_device *vdev)
return 0;
}
+static void __virtnet_vf_setup(struct net_device *ndev,
+ struct net_device *vf_netdev)
+{
+ int ret;
+
+ /* Align MTU of VF with master */
+ ret = dev_set_mtu(vf_netdev, ndev->mtu);
+ if (ret)
+ netdev_warn(vf_netdev,
+ "unable to change mtu to %u\n", ndev->mtu);
+
+ if (netif_running(ndev)) {
+ ret = dev_open(vf_netdev);
+ if (ret)
+ netdev_warn(vf_netdev,
+ "unable to open: %d\n", ret);
+ }
+}
+
+/* Setup VF as slave of the virtio device.
+ * Runs in workqueue to avoid recursion in netlink callbacks.
+ */
+static void virtnet_vf_setup(struct work_struct *w)
+{
+ struct virtnet_info *vi
+ = container_of(w, struct virtnet_info, vf_takeover.work);
+ struct net_device *ndev = vi->dev;
+ struct net_device *vf_netdev;
+
+ if (!rtnl_trylock()) {
+ schedule_delayed_work(&vi->vf_takeover, 0);
+ return;
+ }
+
+ vf_netdev = rtnl_dereference(vi->vf_netdev);
+ if (vf_netdev)
+ __virtnet_vf_setup(ndev, vf_netdev);
+
+ rtnl_unlock();
+}
+
static int virtnet_probe(struct virtio_device *vdev)
{
int i, err;
@@ -2600,6 +2732,11 @@ static int virtnet_probe(struct virtio_device *vdev)
}
INIT_WORK(&vi->config_work, virtnet_config_changed_work);
+ INIT_DELAYED_WORK(&vi->vf_takeover, virtnet_vf_setup);
+
+ vi->vf_stats = netdev_alloc_pcpu_stats(struct virtnet_vf_pcpu_stats);
+ if (!vi->vf_stats)
+ goto free_stats;
/* If we can receive ANY GSO packets, we must allocate large ones. */
if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) ||
@@ -2634,7 +2771,7 @@ static int virtnet_probe(struct virtio_device *vdev)
*/
dev_err(&vdev->dev, "device MTU appears to have changed "
"it is now %d < %d", mtu, dev->min_mtu);
- goto free_stats;
+ goto free_vf_stats;
}
dev->mtu = mtu;
@@ -2658,7 +2795,7 @@ static int virtnet_probe(struct virtio_device *vdev)
/* Allocate/initialize the rx/tx queues, and invoke find_vqs */
err = init_vqs(vi);
if (err)
- goto free_stats;
+ goto free_vf_stats;
#ifdef CONFIG_SYSFS
if (vi->mergeable_rx_bufs)
@@ -2712,6 +2849,8 @@ static int virtnet_probe(struct virtio_device *vdev)
cancel_delayed_work_sync(&vi->refill);
free_receive_page_frags(vi);
virtnet_del_vqs(vi);
+free_vf_stats:
+ free_percpu(vi->vf_stats);
free_stats:
free_percpu(vi->stats);
free:
@@ -2733,19 +2872,178 @@ static void remove_vq_common(struct virtnet_info *vi)
virtnet_del_vqs(vi);
}
+static struct net_device *get_virtio_bymac(const u8 *mac)
+{
+ struct net_device *dev;
+
+ ASSERT_RTNL();
+
+ for_each_netdev(&init_net, dev) {
+ if (dev->netdev_ops != &virtnet_netdev)
+ continue; /* not a virtio_net device */
+
+ if (ether_addr_equal(mac, dev->perm_addr))
+ return dev;
+ }
+
+ return NULL;
+}
+
+static struct net_device *get_virtio_byref(struct net_device *vf_netdev)
+{
+ struct net_device *dev;
+
+ ASSERT_RTNL();
+
+ for_each_netdev(&init_net, dev) {
+ struct virtnet_info *vi;
+
+ if (dev->netdev_ops != &virtnet_netdev)
+ continue; /* not a virtio_net device */
+
+ vi = netdev_priv(dev);
+ if (rtnl_dereference(vi->vf_netdev) == vf_netdev)
+ return dev; /* a match */
+ }
+
+ return NULL;
+}
+
+/* Called when VF is injecting data into network stack.
+ * Change the associated network device from VF to virtio.
+ * note: already called with rcu_read_lock
+ */
+static rx_handler_result_t virtnet_vf_handle_frame(struct sk_buff **pskb)
+{
+ struct sk_buff *skb = *pskb;
+ struct net_device *ndev = rcu_dereference(skb->dev->rx_handler_data);
+ struct virtnet_info *vi = netdev_priv(ndev);
+ struct virtnet_vf_pcpu_stats *pcpu_stats + this_cpu_ptr(vi->vf_stats);
+
+ skb->dev = ndev;
+
+ u64_stats_update_begin(&pcpu_stats->syncp);
+ pcpu_stats->rx_packets++;
+ pcpu_stats->rx_bytes += skb->len;
+ u64_stats_update_end(&pcpu_stats->syncp);
+
+ return RX_HANDLER_ANOTHER;
+}
+
+static int virtnet_vf_join(struct net_device *vf_netdev,
+ struct net_device *ndev)
+{
+ struct virtnet_info *vi = netdev_priv(ndev);
+ int ret;
+
+ ret = netdev_rx_handler_register(vf_netdev,
+ virtnet_vf_handle_frame, ndev);
+ if (ret != 0) {
+ netdev_err(vf_netdev,
+ "can not register virtio VF receive handler (err = %d)\n",
+ ret);
+ goto rx_handler_failed;
+ }
+
+ ret = netdev_upper_dev_link(vf_netdev, ndev, NULL);
+ if (ret != 0) {
+ netdev_err(vf_netdev,
+ "can not set master device %s (err = %d)\n",
+ ndev->name, ret);
+ goto upper_link_failed;
+ }
+
+ /* set slave flag before open to prevent IPv6 addrconf */
+ vf_netdev->flags |= IFF_SLAVE;
+
+ schedule_delayed_work(&vi->vf_takeover, VF_TAKEOVER_INT);
+
+ call_netdevice_notifiers(NETDEV_JOIN, vf_netdev);
+
+ netdev_info(vf_netdev, "joined to %s\n", ndev->name);
+ return 0;
+
+upper_link_failed:
+ netdev_rx_handler_unregister(vf_netdev);
+rx_handler_failed:
+ return ret;
+}
+
+static int virtnet_register_vf(struct net_device *vf_netdev)
+{
+ struct net_device *ndev;
+ struct virtnet_info *vi;
+
+ if (vf_netdev->addr_len != ETH_ALEN)
+ return NOTIFY_DONE;
+
+ /* We will use the MAC address to locate the virtio_net interface to
+ * associate with the VF interface. If we don't find a matching
+ * virtio interface, move on.
+ */
+ ndev = get_virtio_bymac(vf_netdev->perm_addr);
+ if (!ndev)
+ return NOTIFY_DONE;
+
+ vi = netdev_priv(ndev);
+ if (rtnl_dereference(vi->vf_netdev))
+ return NOTIFY_DONE;
+
+ if (virtnet_vf_join(vf_netdev, ndev) != 0)
+ return NOTIFY_DONE;
+
+ netdev_info(ndev, "VF registering %s\n", vf_netdev->name);
+
+ dev_hold(vf_netdev);
+ rcu_assign_pointer(vi->vf_netdev, vf_netdev);
+
+ return NOTIFY_OK;
+}
+
+static int virtnet_unregister_vf(struct net_device *vf_netdev)
+{
+ struct net_device *ndev;
+ struct virtnet_info *vi;
+
+ ndev = get_virtio_byref(vf_netdev);
+ if (!ndev)
+ return NOTIFY_DONE;
+
+ vi = netdev_priv(ndev);
+ cancel_delayed_work_sync(&vi->vf_takeover);
+
+ netdev_info(ndev, "VF unregistering %s\n", vf_netdev->name);
+
+ netdev_rx_handler_unregister(vf_netdev);
+ netdev_upper_dev_unlink(vf_netdev, ndev);
+ RCU_INIT_POINTER(vi->vf_netdev, NULL);
+ dev_put(vf_netdev);
+
+ return NOTIFY_OK;
+}
+
static void virtnet_remove(struct virtio_device *vdev)
{
struct virtnet_info *vi = vdev->priv;
+ struct net_device *vf_netdev;
virtnet_cpu_notif_remove(vi);
/* Make sure no work handler is accessing the device. */
flush_work(&vi->config_work);
+ rtnl_lock();
+ vf_netdev = rtnl_dereference(vi->vf_netdev);
+ if (vf_netdev)
+ virtnet_unregister_vf(vf_netdev);
+ rtnl_unlock();
+
unregister_netdev(vi->dev);
remove_vq_common(vi);
+ free_percpu(vi->vf_stats);
free_percpu(vi->stats);
free_netdev(vi->dev);
}
@@ -2823,6 +3121,42 @@ static struct virtio_driver virtio_net_driver = {
#endif
};
+static int virtio_netdev_event(struct notifier_block *this,
+ unsigned long event, void *ptr)
+{
+ struct net_device *event_dev = netdev_notifier_info_to_dev(ptr);
+
+ /* Skip our own events */
+ if (event_dev->netdev_ops == &virtnet_netdev)
+ return NOTIFY_DONE;
+
+ /* Avoid non-Ethernet type devices */
+ if (event_dev->type != ARPHRD_ETHER)
+ return NOTIFY_DONE;
+
+ /* Avoid Vlan dev with same MAC registering as VF */
+ if (is_vlan_dev(event_dev))
+ return NOTIFY_DONE;
+
+ /* Avoid Bonding master dev with same MAC registering as VF */
+ if ((event_dev->priv_flags & IFF_BONDING) &&
+ (event_dev->flags & IFF_MASTER))
+ return NOTIFY_DONE;
+
+ switch (event) {
+ case NETDEV_REGISTER:
+ return virtnet_register_vf(event_dev);
+ case NETDEV_UNREGISTER:
+ return virtnet_unregister_vf(event_dev);
+ default:
+ return NOTIFY_DONE;
+ }
+}
+
+static struct notifier_block virtio_netdev_notifier = {
+ .notifier_call = virtio_netdev_event,
+};
+
static __init int virtio_net_driver_init(void)
{
int ret;
@@ -2841,6 +3175,8 @@ static __init int virtio_net_driver_init(void)
ret = register_virtio_driver(&virtio_net_driver);
if (ret)
goto err_virtio;
+
+ register_netdevice_notifier(&virtio_netdev_notifier);
return 0;
err_virtio:
cpuhp_remove_multi_state(CPUHP_VIRT_NET_DEAD);
@@ -2853,6 +3189,7 @@ module_init(virtio_net_driver_init);
static __exit void virtio_net_driver_exit(void)
{
+ unregister_netdevice_notifier(&virtio_netdev_notifier);
unregister_virtio_driver(&virtio_net_driver);
cpuhp_remove_multi_state(CPUHP_VIRT_NET_DEAD);
cpuhp_remove_multi_state(virtionet_online);
--
2.14.3
Michael S. Tsirkin
2017-Dec-19 15:47 UTC
[RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
I'll need to look at this more, in particular the feature bit is missing here. For now one question: On Mon, Dec 18, 2017 at 04:40:36PM -0800, Sridhar Samudrala wrote:> @@ -56,6 +58,8 @@ module_param(napi_tx, bool, 0644); > */ > DECLARE_EWMA(pkt_len, 0, 64) > > +#define VF_TAKEOVER_INT (HZ / 10) > + > #define VIRTNET_DRIVER_VERSION "1.0.0" > > static const unsigned long guest_offloads[] = {Why is this delay necessary? And why by 100ms?
Samudrala, Sridhar
2017-Dec-19 17:41 UTC
[RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
On 12/19/2017 7:47 AM, Michael S. Tsirkin wrote:> I'll need to look at this more, in particular the feature > bit is missing here. For now one question: > > On Mon, Dec 18, 2017 at 04:40:36PM -0800, Sridhar Samudrala wrote: >> @@ -56,6 +58,8 @@ module_param(napi_tx, bool, 0644); >> */ >> DECLARE_EWMA(pkt_len, 0, 64) >> >> +#define VF_TAKEOVER_INT (HZ / 10) >> + >> #define VIRTNET_DRIVER_VERSION "1.0.0" >> >> static const unsigned long guest_offloads[] = { > Why is this delay necessary? And why by 100ms?This is based on netvsc implementation and here is the commit that added this delay.? Not sure if this needs to be 100ms. commit 6123c66854c174e4982f98195100c1d990f9e5e6 Author: stephen hemminger <stephen at networkplumber.org> Date:?? Wed Aug 9 17:46:03 2017 -0700 ??? netvsc: delay setup of VF device ??? When VF device is discovered, delay bring it automatically up in ??? order to allow userspace to some simple changes (like renaming).
Jakub Kicinski
2017-Dec-20 22:33 UTC
[RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
On Mon, 18 Dec 2017 16:40:36 -0800, Sridhar Samudrala wrote:> +static int virtio_netdev_event(struct notifier_block *this, > + unsigned long event, void *ptr) > +{ > + struct net_device *event_dev = netdev_notifier_info_to_dev(ptr); > + > + /* Skip our own events */ > + if (event_dev->netdev_ops == &virtnet_netdev) > + return NOTIFY_DONE;I wonder how does this work WRT loop prevention. What if I have two virtio devices with the same MAC, what is preventing them from claiming each other? Is it only the check above (not sure what is "own" in comment referring to)? I'm worried the check above will not stop virtio from enslaving hyperv interfaces and vice versa, potentially leading to a loop, no? There is also the fact that it would be preferable to share the code between paravirt drivers, to avoid duplicated bugs. My suggestion during the previous discussion was to create a paravirt bond device, which will explicitly tell the OS which interfaces to bond, regardless of which driver they're using. Could be some form of ACPI/FW driver too, I don't know enough about x86 FW to suggest something fully fleshed :(
Michael S. Tsirkin
2017-Dec-21 00:14 UTC
[RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
On Mon, Dec 18, 2017 at 04:40:36PM -0800, Sridhar Samudrala wrote:> This patch enables virtio to switch over to a VF datapath when a VF netdev > is present with the same MAC address.I prefer saying "a passthrough device" here. Does not have to be a VF at all.> It allows live migration of a VM > with a direct attached VF without the need to setup a bond/team between a > VF and virtio net device in the guest. > > The hypervisor needs to unplug the VF device from the guest on the source > host and reset the MAC filter of the VF to initiate failover of datapath to > virtio before starting the migration. After the migration is completed, the > destination hypervisor sets the MAC filter on the VF and plugs it back to > the guest to switch over to VF datapath. > > It is entirely based on netvsc implementation and it should be possible to > make this code generic and move it to a common location that can be shared > by netvsc and virtio. > > Also, i think we should make this a negotiated feature that is off by > default via a new feature bit.So please include this. A copy needs to go to virtio TC to reserve the bit. Enabling this by default risks breaking too many configurations.> > This patch is based on the discussion initiated by Jesse on this thread. > https://marc.info/?l=linux-virtualization&m=151189725224231&w=2 > > Signed-off-by: Sridhar Samudrala <sridhar.samudrala at intel.com> > Reviewed-by: Jesse Brandeburg <jesse.brandeburg at intel.com> > --- > drivers/net/virtio_net.c | 341 ++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 339 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 559b215c0169..a34c717bb15b 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -31,6 +31,8 @@ > #include <linux/average.h> > #include <linux/filter.h> > #include <net/route.h> > +#include <linux/netdevice.h> > +#include <linux/netpoll.h> > > static int napi_weight = NAPI_POLL_WEIGHT; > module_param(napi_weight, int, 0444); > @@ -56,6 +58,8 @@ module_param(napi_tx, bool, 0644); > */ > DECLARE_EWMA(pkt_len, 0, 64) > > +#define VF_TAKEOVER_INT (HZ / 10) > + > #define VIRTNET_DRIVER_VERSION "1.0.0" > > static const unsigned long guest_offloads[] = { > @@ -117,6 +121,15 @@ struct receive_queue { > char name[40]; > }; > > +struct virtnet_vf_pcpu_stats { > + u64 rx_packets; > + u64 rx_bytes; > + u64 tx_packets; > + u64 tx_bytes; > + struct u64_stats_sync syncp; > + u32 tx_dropped; > +}; > + > struct virtnet_info { > struct virtio_device *vdev; > struct virtqueue *cvq; > @@ -179,6 +192,11 @@ struct virtnet_info { > u32 speed; > > unsigned long guest_offloads; > + > + /* State to manage the associated VF interface. */ > + struct net_device __rcu *vf_netdev; > + struct virtnet_vf_pcpu_stats __percpu *vf_stats; > + struct delayed_work vf_takeover; > }; > > struct padded_vnet_hdr { > @@ -1300,16 +1318,51 @@ static int xmit_skb(struct send_queue *sq, struct sk_buff *skb) > return virtqueue_add_outbuf(sq->vq, sq->sg, num_sg, skb, GFP_ATOMIC); > } > > +/* Send skb on the slave VF device. */ > +static int virtnet_vf_xmit(struct net_device *dev, struct net_device *vf_netdev, > + struct sk_buff *skb) > +{ > + struct virtnet_info *vi = netdev_priv(dev); > + unsigned int len = skb->len; > + int rc; > + > + skb->dev = vf_netdev; > + skb->queue_mapping = qdisc_skb_cb(skb)->slave_dev_queue_mapping; > + > + rc = dev_queue_xmit(skb); > + if (likely(rc == NET_XMIT_SUCCESS || rc == NET_XMIT_CN)) { > + struct virtnet_vf_pcpu_stats *pcpu_stats > + = this_cpu_ptr(vi->vf_stats); > + > + u64_stats_update_begin(&pcpu_stats->syncp); > + pcpu_stats->tx_packets++; > + pcpu_stats->tx_bytes += len; > + u64_stats_update_end(&pcpu_stats->syncp); > + } else { > + this_cpu_inc(vi->vf_stats->tx_dropped); > + } > + > + return rc; > +} > + > static netdev_tx_t start_xmit(struct sk_buff *skb, struct net_device *dev) > { > struct virtnet_info *vi = netdev_priv(dev); > int qnum = skb_get_queue_mapping(skb); > struct send_queue *sq = &vi->sq[qnum]; > + struct net_device *vf_netdev; > int err; > struct netdev_queue *txq = netdev_get_tx_queue(dev, qnum); > bool kick = !skb->xmit_more; > bool use_napi = sq->napi.weight; > > + /* if VF is present and up then redirect packets > + * called with rcu_read_lock_bh > + */ > + vf_netdev = rcu_dereference_bh(vi->vf_netdev); > + if (vf_netdev && netif_running(vf_netdev) && !netpoll_tx_running(dev)) > + return virtnet_vf_xmit(dev, vf_netdev, skb); > + > /* Free up any pending old buffers before queueing new ones. */ > free_old_xmit_skbs(sq); > > @@ -1456,10 +1509,41 @@ static int virtnet_set_mac_address(struct net_device *dev, void *p) > return ret; > } > > +static void virtnet_get_vf_stats(struct net_device *dev, > + struct virtnet_vf_pcpu_stats *tot) > +{ > + struct virtnet_info *vi = netdev_priv(dev); > + int i; > + > + memset(tot, 0, sizeof(*tot)); > + > + for_each_possible_cpu(i) { > + const struct virtnet_vf_pcpu_stats *stats > + = per_cpu_ptr(vi->vf_stats, i); > + u64 rx_packets, rx_bytes, tx_packets, tx_bytes; > + unsigned int start; > + > + do { > + start = u64_stats_fetch_begin_irq(&stats->syncp); > + rx_packets = stats->rx_packets; > + tx_packets = stats->tx_packets; > + rx_bytes = stats->rx_bytes; > + tx_bytes = stats->tx_bytes; > + } while (u64_stats_fetch_retry_irq(&stats->syncp, start)); > + > + tot->rx_packets += rx_packets; > + tot->tx_packets += tx_packets; > + tot->rx_bytes += rx_bytes; > + tot->tx_bytes += tx_bytes; > + tot->tx_dropped += stats->tx_dropped; > + } > +} > + > static void virtnet_stats(struct net_device *dev, > struct rtnl_link_stats64 *tot) > { > struct virtnet_info *vi = netdev_priv(dev); > + struct virtnet_vf_pcpu_stats vf_stats; > int cpu; > unsigned int start; > > @@ -1490,6 +1574,13 @@ static void virtnet_stats(struct net_device *dev, > tot->rx_dropped = dev->stats.rx_dropped; > tot->rx_length_errors = dev->stats.rx_length_errors; > tot->rx_frame_errors = dev->stats.rx_frame_errors; > + > + virtnet_get_vf_stats(dev, &vf_stats); > + tot->rx_packets += vf_stats.rx_packets; > + tot->tx_packets += vf_stats.tx_packets; > + tot->rx_bytes += vf_stats.rx_bytes; > + tot->tx_bytes += vf_stats.tx_bytes; > + tot->tx_dropped += vf_stats.tx_dropped; > } > > #ifdef CONFIG_NET_POLL_CONTROLLER > @@ -2508,6 +2599,47 @@ static int virtnet_validate(struct virtio_device *vdev) > return 0; > } > > +static void __virtnet_vf_setup(struct net_device *ndev, > + struct net_device *vf_netdev) > +{ > + int ret; > + > + /* Align MTU of VF with master */ > + ret = dev_set_mtu(vf_netdev, ndev->mtu); > + if (ret) > + netdev_warn(vf_netdev, > + "unable to change mtu to %u\n", ndev->mtu); > + > + if (netif_running(ndev)) { > + ret = dev_open(vf_netdev); > + if (ret) > + netdev_warn(vf_netdev, > + "unable to open: %d\n", ret); > + } > +} > + > +/* Setup VF as slave of the virtio device. > + * Runs in workqueue to avoid recursion in netlink callbacks. > + */ > +static void virtnet_vf_setup(struct work_struct *w) > +{ > + struct virtnet_info *vi > + = container_of(w, struct virtnet_info, vf_takeover.work); > + struct net_device *ndev = vi->dev; > + struct net_device *vf_netdev; > + > + if (!rtnl_trylock()) { > + schedule_delayed_work(&vi->vf_takeover, 0); > + return; > + } > + > + vf_netdev = rtnl_dereference(vi->vf_netdev); > + if (vf_netdev) > + __virtnet_vf_setup(ndev, vf_netdev); > + > + rtnl_unlock(); > +} > + > static int virtnet_probe(struct virtio_device *vdev) > { > int i, err; > @@ -2600,6 +2732,11 @@ static int virtnet_probe(struct virtio_device *vdev) > } > > INIT_WORK(&vi->config_work, virtnet_config_changed_work); > + INIT_DELAYED_WORK(&vi->vf_takeover, virtnet_vf_setup); > + > + vi->vf_stats = netdev_alloc_pcpu_stats(struct virtnet_vf_pcpu_stats); > + if (!vi->vf_stats) > + goto free_stats; > > /* If we can receive ANY GSO packets, we must allocate large ones. */ > if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) || > @@ -2634,7 +2771,7 @@ static int virtnet_probe(struct virtio_device *vdev) > */ > dev_err(&vdev->dev, "device MTU appears to have changed " > "it is now %d < %d", mtu, dev->min_mtu); > - goto free_stats; > + goto free_vf_stats; > } > > dev->mtu = mtu; > @@ -2658,7 +2795,7 @@ static int virtnet_probe(struct virtio_device *vdev) > /* Allocate/initialize the rx/tx queues, and invoke find_vqs */ > err = init_vqs(vi); > if (err) > - goto free_stats; > + goto free_vf_stats; > > #ifdef CONFIG_SYSFS > if (vi->mergeable_rx_bufs) > @@ -2712,6 +2849,8 @@ static int virtnet_probe(struct virtio_device *vdev) > cancel_delayed_work_sync(&vi->refill); > free_receive_page_frags(vi); > virtnet_del_vqs(vi); > +free_vf_stats: > + free_percpu(vi->vf_stats); > free_stats: > free_percpu(vi->stats); > free: > @@ -2733,19 +2872,178 @@ static void remove_vq_common(struct virtnet_info *vi) > virtnet_del_vqs(vi); > } > > +static struct net_device *get_virtio_bymac(const u8 *mac) > +{ > + struct net_device *dev; > + > + ASSERT_RTNL(); > + > + for_each_netdev(&init_net, dev) { > + if (dev->netdev_ops != &virtnet_netdev) > + continue; /* not a virtio_net device */ > + > + if (ether_addr_equal(mac, dev->perm_addr)) > + return dev; > + } > + > + return NULL; > +} > + > +static struct net_device *get_virtio_byref(struct net_device *vf_netdev) > +{ > + struct net_device *dev; > + > + ASSERT_RTNL(); > + > + for_each_netdev(&init_net, dev) { > + struct virtnet_info *vi; > + > + if (dev->netdev_ops != &virtnet_netdev) > + continue; /* not a virtio_net device */ > + > + vi = netdev_priv(dev); > + if (rtnl_dereference(vi->vf_netdev) == vf_netdev) > + return dev; /* a match */ > + } > + > + return NULL; > +} > + > +/* Called when VF is injecting data into network stack. > + * Change the associated network device from VF to virtio. > + * note: already called with rcu_read_lock > + */ > +static rx_handler_result_t virtnet_vf_handle_frame(struct sk_buff **pskb) > +{ > + struct sk_buff *skb = *pskb; > + struct net_device *ndev = rcu_dereference(skb->dev->rx_handler_data); > + struct virtnet_info *vi = netdev_priv(ndev); > + struct virtnet_vf_pcpu_stats *pcpu_stats > + this_cpu_ptr(vi->vf_stats); > + > + skb->dev = ndev; > + > + u64_stats_update_begin(&pcpu_stats->syncp); > + pcpu_stats->rx_packets++; > + pcpu_stats->rx_bytes += skb->len; > + u64_stats_update_end(&pcpu_stats->syncp); > + > + return RX_HANDLER_ANOTHER; > +} > + > +static int virtnet_vf_join(struct net_device *vf_netdev, > + struct net_device *ndev) > +{ > + struct virtnet_info *vi = netdev_priv(ndev); > + int ret; > + > + ret = netdev_rx_handler_register(vf_netdev, > + virtnet_vf_handle_frame, ndev); > + if (ret != 0) { > + netdev_err(vf_netdev, > + "can not register virtio VF receive handler (err = %d)\n", > + ret); > + goto rx_handler_failed; > + } > + > + ret = netdev_upper_dev_link(vf_netdev, ndev, NULL); > + if (ret != 0) { > + netdev_err(vf_netdev, > + "can not set master device %s (err = %d)\n", > + ndev->name, ret); > + goto upper_link_failed; > + } > + > + /* set slave flag before open to prevent IPv6 addrconf */ > + vf_netdev->flags |= IFF_SLAVE; > + > + schedule_delayed_work(&vi->vf_takeover, VF_TAKEOVER_INT); > + > + call_netdevice_notifiers(NETDEV_JOIN, vf_netdev); > + > + netdev_info(vf_netdev, "joined to %s\n", ndev->name); > + return 0; > + > +upper_link_failed: > + netdev_rx_handler_unregister(vf_netdev); > +rx_handler_failed: > + return ret; > +} > + > +static int virtnet_register_vf(struct net_device *vf_netdev) > +{ > + struct net_device *ndev; > + struct virtnet_info *vi; > + > + if (vf_netdev->addr_len != ETH_ALEN) > + return NOTIFY_DONE; > + > + /* We will use the MAC address to locate the virtio_net interface to > + * associate with the VF interface. If we don't find a matching > + * virtio interface, move on. > + */ > + ndev = get_virtio_bymac(vf_netdev->perm_addr); > + if (!ndev) > + return NOTIFY_DONE; > + > + vi = netdev_priv(ndev); > + if (rtnl_dereference(vi->vf_netdev)) > + return NOTIFY_DONE; > + > + if (virtnet_vf_join(vf_netdev, ndev) != 0) > + return NOTIFY_DONE; > + > + netdev_info(ndev, "VF registering %s\n", vf_netdev->name); > + > + dev_hold(vf_netdev); > + rcu_assign_pointer(vi->vf_netdev, vf_netdev); > + > + return NOTIFY_OK; > +} > + > +static int virtnet_unregister_vf(struct net_device *vf_netdev) > +{ > + struct net_device *ndev; > + struct virtnet_info *vi; > + > + ndev = get_virtio_byref(vf_netdev); > + if (!ndev) > + return NOTIFY_DONE; > + > + vi = netdev_priv(ndev); > + cancel_delayed_work_sync(&vi->vf_takeover); > + > + netdev_info(ndev, "VF unregistering %s\n", vf_netdev->name); > + > + netdev_rx_handler_unregister(vf_netdev); > + netdev_upper_dev_unlink(vf_netdev, ndev); > + RCU_INIT_POINTER(vi->vf_netdev, NULL); > + dev_put(vf_netdev); > + > + return NOTIFY_OK; > +} > + > static void virtnet_remove(struct virtio_device *vdev) > { > struct virtnet_info *vi = vdev->priv; > + struct net_device *vf_netdev; > > virtnet_cpu_notif_remove(vi); > > /* Make sure no work handler is accessing the device. */ > flush_work(&vi->config_work); > > + rtnl_lock(); > + vf_netdev = rtnl_dereference(vi->vf_netdev); > + if (vf_netdev) > + virtnet_unregister_vf(vf_netdev); > + rtnl_unlock(); > + > unregister_netdev(vi->dev); > > remove_vq_common(vi); > > + free_percpu(vi->vf_stats); > free_percpu(vi->stats); > free_netdev(vi->dev); > } > @@ -2823,6 +3121,42 @@ static struct virtio_driver virtio_net_driver = { > #endif > }; > > +static int virtio_netdev_event(struct notifier_block *this, > + unsigned long event, void *ptr) > +{ > + struct net_device *event_dev = netdev_notifier_info_to_dev(ptr); > + > + /* Skip our own events */ > + if (event_dev->netdev_ops == &virtnet_netdev) > + return NOTIFY_DONE; > + > + /* Avoid non-Ethernet type devices */ > + if (event_dev->type != ARPHRD_ETHER) > + return NOTIFY_DONE; > + > + /* Avoid Vlan dev with same MAC registering as VF */ > + if (is_vlan_dev(event_dev)) > + return NOTIFY_DONE; > + > + /* Avoid Bonding master dev with same MAC registering as VF */ > + if ((event_dev->priv_flags & IFF_BONDING) && > + (event_dev->flags & IFF_MASTER)) > + return NOTIFY_DONE; > + > + switch (event) { > + case NETDEV_REGISTER: > + return virtnet_register_vf(event_dev); > + case NETDEV_UNREGISTER: > + return virtnet_unregister_vf(event_dev); > + default: > + return NOTIFY_DONE; > + } > +} > + > +static struct notifier_block virtio_netdev_notifier = { > + .notifier_call = virtio_netdev_event, > +}; > + > static __init int virtio_net_driver_init(void) > { > int ret; > @@ -2841,6 +3175,8 @@ static __init int virtio_net_driver_init(void) > ret = register_virtio_driver(&virtio_net_driver); > if (ret) > goto err_virtio; > + > + register_netdevice_notifier(&virtio_netdev_notifier); > return 0; > err_virtio: > cpuhp_remove_multi_state(CPUHP_VIRT_NET_DEAD); > @@ -2853,6 +3189,7 @@ module_init(virtio_net_driver_init); > > static __exit void virtio_net_driver_exit(void) > { > + unregister_netdevice_notifier(&virtio_netdev_notifier); > unregister_virtio_driver(&virtio_net_driver); > cpuhp_remove_multi_state(CPUHP_VIRT_NET_DEAD); > cpuhp_remove_multi_state(virtionet_online); > -- > 2.14.3
Michael S. Tsirkin
2017-Dec-21 00:15 UTC
[RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
On Wed, Dec 20, 2017 at 02:33:34PM -0800, Jakub Kicinski wrote:> On Mon, 18 Dec 2017 16:40:36 -0800, Sridhar Samudrala wrote: > > +static int virtio_netdev_event(struct notifier_block *this, > > + unsigned long event, void *ptr) > > +{ > > + struct net_device *event_dev = netdev_notifier_info_to_dev(ptr); > > + > > + /* Skip our own events */ > > + if (event_dev->netdev_ops == &virtnet_netdev) > > + return NOTIFY_DONE; > > I wonder how does this work WRT loop prevention. What if I have two > virtio devices with the same MAC, what is preventing them from claiming > each other? Is it only the check above (not sure what is "own" in > comment referring to)?I expect we will add a feature bit (VIRTIO_NET_F_MASTER) and it will be host's responsibility not to add more than 1 such device.> I'm worried the check above will not stop virtio from enslaving hyperv > interfaces and vice versa, potentially leading to a loop, no? There is > also the fact that it would be preferable to share the code between > paravirt drivers, to avoid duplicated bugs. > > My suggestion during the previous discussion was to create a paravirt > bond device, which will explicitly tell the OS which interfaces to > bond, regardless of which driver they're using. Could be some form of > ACPI/FW driver too, I don't know enough about x86 FW to suggest > something fully fleshed :(
Possibly Parallel Threads
- [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
- [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
- [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
- [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available
- [RFC PATCH] virtio_net: Extend virtio to use VF datapath when available