From 4b784cf8b4f2deadd3c6074eb3ce6e571b09eee8 Mon Sep 17 00:00:00 2001
From: Miguel Di Ciurcio Filho <miguel.filho@gmail.com>
Date: Thu, 2 Dec 2010 14:00:10 -0200
Subject: [PATCH] kvm: Improve network syntax and tests

The current syntax when defining a NIC uses a pair of arguments, like this:

-net tap,vlan=0 -net nic,vlan=0,model=virtio

When using this pair, internally KVM will create a VLANState structure to send
ethernet frames between the guest NIC and the host tap device. This is
suboptimal and is going to be removed in the future. Plus, this combination
breaks vhost-net support.

The new syntax does not need the vlan craziness anymore, creating a direct 1:1
relationship between the backend device and the frontend device.

-netdev tap,id=netdev0 -device virtio-net-pci,mac=52:54:00:56:6c:55,netdev=netdev0

The current code does not verify if vhost_net is available before starting an
instance. All this tests are done verifying the KVM version installed on the
node.

Signed-off-by: Miguel Di Ciurcio Filho <miguel.filho@gmail.com>
Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>
---
 lib/hypervisor/hv_kvm.py | 34 +++++++++++++++++++++++++++-------
 1 file changed, 27 insertions(+), 7 deletions(-)

diff --git a/lib/hypervisor/hv_kvm.py b/lib/hypervisor/hv_kvm.py
index 671b8dfd5..bd969cf87 100644
--- a/lib/hypervisor/hv_kvm.py
+++ b/lib/hypervisor/hv_kvm.py
@@ -722,6 +722,12 @@ class KVMHypervisor(hv_base.BaseHypervisor):
     kvm_cmd, kvm_nics, up_hvp = kvm_runtime
     up_hvp = objects.FillDict(conf_hvp, up_hvp)
 
+    kvm_version = self._GetKVMVersion()
+    if kvm_version:
+      _, v_major, v_min, v_rev = kvm_version
+    else:
+      raise errors.HypervisorError("Unable to get KVM version")
+
     # We know it's safe to run as a different user upon migration, so we'll use
     # the latest conf, from conf_hvp.
     security_model = conf_hvp[constants.HV_SECURITY_MODEL]
@@ -737,19 +743,33 @@ class KVMHypervisor(hv_base.BaseHypervisor):
       tap_extra = ""
       nic_type = up_hvp[constants.HV_NIC_TYPE]
       if nic_type == constants.HT_NIC_PARAVIRTUAL:
-        nic_model = "model=virtio"
+        # From version 0.12.0, kvm uses a new sintax for network configuration.
+        if (v_major, v_min) >= (0,12):
+          nic_model = "virtio-net-pci"
+        else:
+          nic_model = "virtio"
+
         if up_hvp[constants.HV_VHOST_NET]:
-          tap_extra = ",vhost=on"
+          # vhost_net is only available from version 0.13.0 or newer
+          if (v_major, v_min) >= (0,13):
+            tap_extra = ",vhost=on"
+          else:
+            raise errors.HypervisorError("vhost_net is configured"
+                                        " but it is not available")
       else:
-        nic_model = "model=%s" % nic_type
+        nic_model = nic_type
 
       for nic_seq, nic in enumerate(kvm_nics):
-        nic_val = "nic,vlan=%s,macaddr=%s,%s" % (nic_seq, nic.mac, nic_model)
         script = self._WriteNetScriptFile(instance, nic_seq, nic)
-        tap_val = "tap,vlan=%s,script=%s%s" % (nic_seq, script, tap_extra)
-        kvm_cmd.extend(["-net", nic_val])
-        kvm_cmd.extend(["-net", tap_val])
         temp_files.append(script)
+        if (v_major, v_min) >= (0,12):
+          nic_val = "%s,mac=%s,netdev=netdev%s" % (nic_model, nic.mac, nic_seq)
+          tap_val = "type=tap,id=netdev%s,script=%s%s" % (nic_seq, script, tap_extra)
+          kvm_cmd.extend(["-netdev", tap_val, "-device", nic_val])
+        else:
+          nic_val = "nic,vlan=%s,macaddr=%s,model=%s" % (nic_seq, nic.mac, nic_model)
+          tap_val = "tap,vlan=%s,script=%s" % (nic_seq, script)
+          kvm_cmd.extend(["-net", tap_val, "-net", nic_val])
 
     if incoming:
       target, port = incoming
-- 
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