This method will create and open a macvtap device using the `ip-link`
command.
It takes as arguments the name of the device to be created, its mac
address, the macvtap mode, the link where the macvtap device will be
attached to, and a dictionary of features to be enabled for the device.
Currently, these features are vhost, and multiqueue. The vnet_hdr is
enabled by default and there is no way to disable it, after creating the
device.
Also, we've created a helper method to get the fds of the /dev/vhost-net
device, since that part of code will be used by both the OpenMacVTap and
OpenTap methods.
Signed-off-by: Dimitris Bliablias <db...@skroutz.gr>
---
lib/hypervisor/hv_kvm/netdev.py | 99 +++++++++++++++++++++++++++++++++++++----
1 file changed, 90 insertions(+), 9 deletions(-)
diff --git a/lib/hypervisor/hv_kvm/netdev.py b/lib/hypervisor/hv_kvm/netdev.py
index 852d48f..c65aef8 100644
--- a/lib/hypervisor/hv_kvm/netdev.py
+++ b/lib/hypervisor/hv_kvm/netdev.py
@@ -37,7 +37,9 @@ import logging
import struct
import fcntl
+from ganeti import utils
from ganeti import errors
+from ganeti import constants
# TUN/TAP driver constants, taken from <linux/if_tun.h>
@@ -124,6 +126,21 @@ def _ProbeTapMqVirtioNet(fd, _features_fn=_GetTunFeatures):
return result
+def _GetVhostFd():
+ """Return a /dev/vhost-net file descriptor.
+
+ This is done regularly by the qemu process if vhost=on was passed with
+ --netdev option. Still, in case of hotplug and if the process does not
+ run with root privileges, we have to get the fds and pass them via
+ SCM_RIGHTS prior to qemu using them.
+
+ """
+ try:
+ return os.open("/dev/vhost-net", os.O_RDWR)
+ except EnvironmentError:
+ raise errors.HypervisorError("Failed to open /dev/vhost-net")
+
+
def OpenTap(name="", features=None):
"""Open a new tap device and return its file descriptor.
@@ -177,15 +194,7 @@ def OpenTap(name="", features=None):
err)
if vhost:
- # This is done regularly by the qemu process if vhost=on was passed with
- # --netdev option. Still, in case of hotplug and if the process does not
- # run with root privileges, we have to get the fds and pass them via
- # SCM_RIGHTS prior to qemu using them.
- try:
- vhostfd = os.open("/dev/vhost-net", os.O_RDWR)
- vhostfds.append(vhostfd)
- except EnvironmentError:
- raise errors.HypervisorError("Failed to open /dev/vhost-net")
+ vhostfds.append(_GetVhostFd())
tapfds.append(tapfd)
@@ -193,3 +202,75 @@ def OpenTap(name="", features=None):
ifname = struct.unpack("16sh", res)[0].strip("\x00")
return (ifname, tapfds, vhostfds)
+
+
+def OpenMacVTap(name, link, mac, macvtap_mode, features=None):
+ """Open a new macvtap device and return its file descriptor.
+
+ This is intended to be used by a qemu-type hypervisor together with the
+ -netdev type=tap,fd=<fd>,id=<id> -device virtio-net-pci,netdev=<id>,mac=<mac>
+ command line parameter.
+
+ @type name: string
+ @param name: name for the macvtap interface to be created; name created
+ using the L{hv_base.GenerateTapName} helper method
+ @type link: string
+ @param link: specifies the physical device to operate on
+ @type mac: string
+ @param mac: specifies the MAC address of the macvtap interface
+ @type macvtap_mode: string
+ @param macvtap_mode: specifies the type of the new device; vepa, bridge,
+ private, or passthru
+ @type features: dict
+ @param features: A dict denoting whether vhost or mq netdev features
+ are enabled or not
+
+ @rtype: tuple
+ @return: (ifname, [tapfd], [vhostfd])
+
+ """
+ ifname = name
+ tapfd = []
+ vhostfd = []
+
+ if features is None:
+ features = {}
+ vhost = features.get("vhost", False)
+ _, virtio_net_queues = features.get("mq", (False, 1))
+
+ if not ifname:
+ raise errors.HypervisorError("Cannot create macvtap device: device name"
+ " is empty")
+
+ # Construct the ip-link command for the macvtap interface
+ cmd = ["ip", "link", "add"]
+ cmd.extend(["link", link])
+ cmd.extend(["name", name])
+ cmd.extend(["address", mac])
+ if virtio_net_queues > 1:
+ cmd.extend(["numtxqueues", virtio_net_queues])
+ cmd.extend(["numrxqueues", virtio_net_queues])
+ cmd.extend(["type", constants.NIC_MODE_MACVTAP])
+ cmd.extend(["mode", macvtap_mode])
+
+ result = utils.RunCmd(cmd)
+ if result.failed:
+ raise errors.HypervisorError("Failed to create macvtap device: %s (%s)" %
+ (ifname, result.fail_reason))
+
+ try:
+ with open(utils.PathJoin("/sys/class/net", name, "ifindex"), "r") as fd:
+ ifindex = fd.read().strip()
+ except IOError, err:
+ raise errors.HypervisorError("Failed to read from sysfs %s: %s" %
+ (name, err))
+
+ try:
+ tapfd.append(os.open("/dev/tap%s" % ifindex, os.O_RDWR))
+ except EnvironmentError:
+ raise errors.HypervisorError("Failed to open /dev/tap%s" % ifindex)
+
+ if vhost:
+ vhostfd = [_GetVhostFd()]
+
+ return (ifname, tapfd, vhostfd)
--
2.1.4
