Blame qemu-virtio-net-vhost-net-support.patch

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This connects virtio-net to vhost net backend.
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The code is structured in a way analogous to what we have with vnet
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header capability in tap.  We start/stop backend on driver start/stop as
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well as on save and vm start (for migration).
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Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
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---
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 hw/virtio-net.c |   67 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
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 1 files changed, 65 insertions(+), 2 deletions(-)
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diff --git a/hw/virtio-net.c b/hw/virtio-net.c
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index 02d9180..088029b 100644
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--- a/hw/virtio-net.c
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+++ b/hw/virtio-net.c
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@@ -17,6 +17,7 @@
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 #include "net/tap.h"
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 #include "qemu-timer.h"
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 #include "virtio-net.h"
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+#include "vhost_net.h"
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 #define VIRTIO_NET_VM_VERSION    11
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@@ -47,6 +48,8 @@ typedef struct VirtIONet
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     uint8_t nomulti;
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     uint8_t nouni;
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     uint8_t nobcast;
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+    uint8_t vhost_started;
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+    VMChangeStateEntry *vmstate;
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     struct {
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         int in_use;
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         int first_multi;
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@@ -114,6 +117,10 @@ static void virtio_net_reset(VirtIODevice *vdev)
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     n->nomulti = 0;
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     n->nouni = 0;
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     n->nobcast = 0;
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+    if (n->vhost_started) {
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+        vhost_net_stop(tap_get_vhost_net(n->nic->nc.peer), vdev);
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+        n->vhost_started = 0;
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+    }
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     /* Flush any MAC and VLAN filter table state */
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     n->mac_table.in_use = 0;
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@@ -172,7 +179,10 @@ static uint32_t virtio_net_get_features(VirtIODevice *vdev, uint32_t features)
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         features &= ~(0x1 << VIRTIO_NET_F_HOST_UFO);
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     }
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-    return features;
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+    if (!tap_get_vhost_net(n->nic->nc.peer)) {
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+        return features;
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+    }
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+    return vhost_net_get_features(tap_get_vhost_net(n->nic->nc.peer), features);
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 }
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 static uint32_t virtio_net_bad_features(VirtIODevice *vdev)
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@@ -690,6 +700,12 @@ static void virtio_net_save(QEMUFile *f, void *opaque)
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 {
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     VirtIONet *n = opaque;
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+    if (n->vhost_started) {
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+	/* TODO: should we really stop the backend?
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+	 * If we don't, it might keep writing to memory. */
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+        vhost_net_stop(tap_get_vhost_net(n->nic->nc.peer), &n->vdev);
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+	n->vhost_started = 0;
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+    }
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     virtio_save(&n->vdev, f);
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     qemu_put_buffer(f, n->mac, ETH_ALEN);
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@@ -802,7 +818,6 @@ static int virtio_net_load(QEMUFile *f, void *opaque, int version_id)
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         qemu_mod_timer(n->tx_timer,
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                        qemu_get_clock(vm_clock) + TX_TIMER_INTERVAL);
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     }
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-
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     return 0;
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 }
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@@ -822,6 +837,47 @@ static NetClientInfo net_virtio_info = {
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     .link_status_changed = virtio_net_set_link_status,
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 };
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+static void virtio_net_set_status(struct VirtIODevice *vdev)
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+{
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+    VirtIONet *n = to_virtio_net(vdev);
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+    if (!n->nic->nc.peer) {
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+        return;
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+    }
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+    if (n->nic->nc.peer->info->type != NET_CLIENT_TYPE_TAP) {
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+        return;
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+    }
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+
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+    if (!tap_get_vhost_net(n->nic->nc.peer)) {
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+        return;
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+    }
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+    if (!!n->vhost_started == !!(vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
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+        return;
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+    }
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+    if (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK) {
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+        int r = vhost_net_start(tap_get_vhost_net(n->nic->nc.peer), vdev);
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+        if (r < 0) {
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+            fprintf(stderr, "unable to start vhost net: %d: "
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+                    "falling back on userspace virtio\n", -r);
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+        } else {
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+            n->vhost_started = 1;
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+        }
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+    } else {
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+        vhost_net_stop(tap_get_vhost_net(n->nic->nc.peer), vdev);
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+        n->vhost_started = 0;
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+    }
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+}
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+
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+static void virtio_net_vmstate_change(void *opaque, int running, int reason)
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+{
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+	VirtIONet *n = opaque;
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+	if (!running) {
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+		return;
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+	}
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+	/* This is called when vm is started, it will start vhost backend if it
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+	 * appropriate e.g. after migration. */
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+	virtio_net_set_status(&n->vdev);
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+}
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+
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 VirtIODevice *virtio_net_init(DeviceState *dev, NICConf *conf)
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 {
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     VirtIONet *n;
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@@ -837,6 +893,7 @@ VirtIODevice *virtio_net_init(DeviceState *dev, NICConf *conf)
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     n->vdev.set_features = virtio_net_set_features;
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     n->vdev.bad_features = virtio_net_bad_features;
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     n->vdev.reset = virtio_net_reset;
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+    n->vdev.set_status = virtio_net_set_status;
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     n->rx_vq = virtio_add_queue(&n->vdev, 256, virtio_net_handle_rx);
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     n->tx_vq = virtio_add_queue(&n->vdev, 256, virtio_net_handle_tx);
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     n->ctrl_vq = virtio_add_queue(&n->vdev, 64, virtio_net_handle_ctrl);
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@@ -859,6 +916,7 @@ VirtIODevice *virtio_net_init(DeviceState *dev, NICConf *conf)
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     register_savevm("virtio-net", virtio_net_id++, VIRTIO_NET_VM_VERSION,
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                     virtio_net_save, virtio_net_load, n);
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+    n->vmstate = qemu_add_vm_change_state_handler(virtio_net_vmstate_change, n);
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     return &n->vdev;
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 }
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@@ -866,6 +924,11 @@ VirtIODevice *virtio_net_init(DeviceState *dev, NICConf *conf)
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 void virtio_net_exit(VirtIODevice *vdev)
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 {
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     VirtIONet *n = DO_UPCAST(VirtIONet, vdev, vdev);
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+    qemu_del_vm_change_state_handler(n->vmstate);
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+
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+    if (n->vhost_started) {
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+        vhost_net_stop(tap_get_vhost_net(n->nic->nc.peer), vdev);
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+    }
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     qemu_purge_queued_packets(&n->nic->nc);
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-- 
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1.6.6.144.g5c3af