kvm: remove last version-based feature detection

This was left behind because it required a different kvm invocation.
Now that we can add new ones cheaply (two constants) it's easy to get
rid of it. Differently than in other cases we support old version which
don't have the actual option, and error out when it's invoked.

This also removes two hardcoded strings, and brings them at constant
level. A lot more are present, but two is megl che one (cit).

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>

diff --git a/lib/hypervisor/hv_kvm.py b/lib/hypervisor/hv_kvm.py
index a25c32d..53a23c4 100644 (file)
--- a/lib/hypervisor/hv_kvm.py
+++ b/lib/hypervisor/hv_kvm.py
@@ -543,6 +543,9 @@ class KVMHypervisor(hv_base.BaseHypervisor):
     constants.HV_KVM_MACHINE_VERSION: hv_base.NO_CHECK,
     }
 
+  _VIRTIO = "virtio"
+  _VIRTIO_NET_PCI = "virtio-net-pci"
+
   _MIGRATION_STATUS_RE = re.compile("Migration\s+status:\s+(\w+)",
                                     re.M | re.I)
   _MIGRATION_PROGRESS_RE = \
@@ -569,6 +572,7 @@ class KVMHypervisor(hv_base.BaseHypervisor):
   _ENABLE_KVM_RE = re.compile(r"^-enable-kvm\s", re.M)
   _DISABLE_KVM_RE = re.compile(r"^-disable-kvm\s", re.M)
   _NETDEV_RE = re.compile(r"^-netdev\s", re.M)
+  _NEW_VIRTIO_RE = re.compile(r"^name \"%s\"" % _VIRTIO_NET_PCI, re.M)
   # match  -drive.*boot=on|off on different lines, but in between accept only
   # dashes not preceeded by a new line (which would mean another option
   # different than -drive is starting)
@@ -584,9 +588,11 @@ class KVMHypervisor(hv_base.BaseHypervisor):
   # Supported kvm options to get output from
   _KVMOPT_HELP = "help"
   _KVMOPT_MLIST = "mlist"
+  _KVMOPT_DEVICELIST = "devicelist"
   _KVMOPTS_CMDS = {
     _KVMOPT_HELP: ["--help"],
     _KVMOPT_MLIST: ["-M", "?"],
+    _KVMOPT_DEVICELIST: ["-device", "?"],
   }
 
   def __init__(self):
@@ -1466,10 +1472,10 @@ class KVMHypervisor(hv_base.BaseHypervisor):
     temp_files = []
 
     kvm_cmd, kvm_nics, up_hvp = kvm_runtime
+    # the first element of kvm_cmd is always the path to the kvm binary
+    kvm_path = kvm_cmd[0]
     up_hvp = objects.FillDict(conf_hvp, up_hvp)
 
-    _, v_major, v_min, _ = self._ParseKVMVersion(kvmhelp)
-
     # 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]
@@ -1498,12 +1504,16 @@ class KVMHypervisor(hv_base.BaseHypervisor):
       tap_extra = ""
       nic_type = up_hvp[constants.HV_NIC_TYPE]
       if nic_type == constants.HT_NIC_PARAVIRTUAL:
-        # 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"
-          vnet_hdr = True
-        else:
-          nic_model = "virtio"
+        nic_model = self._VIRTIO
+        try:
+          devlist = self._GetKVMOutput(kvm_path, self._KVMOPT_DEVICELIST)
+          if self._NEW_VIRTIO_RE.search(devlist):
+            nic_model = self._VIRTIO_NET_PCI
+            vnet_hdr = True
+        except errors.HypervisorError, _:
+          # Older versions of kvm don't support DEVICE_LIST, but they don't
+          # have new virtio syntax either.
+          pass
 
         if up_hvp[constants.HV_VHOST_NET]:
           # check for vhost_net support