[libvirt-users] [libvirt] How to configure MacVtap passthrough mode to SR-IOV VF?

[Jincheng Miao]

> Hi guys.
> These days I'm doing research on SR-IOV & Live migration. As we all know
> there is big problem that SR-IOV & Live migration can not exist at the same
> time.
> I heard that KVM + SRIOV + MacVtap can solve this problem. So I want to try.
> My environment:
> Host: Dell R610, OS: RHEL 6.4 ( kernel 2.6.32)
> NIC: intel 82599
> I follow a document from intel guy, it said that I should write xml like
> below:
> ============================
> <network>
> <name>macvtap_passthrough’</name>
> <forward mode=’passthrough>
> <interface dev=’vf0’ />
> <interface dev=’vf1’ />
> .. ..
> </forward>
> </network>
> ============================
> I guess here the vf0 & vf1 should be the VFs of Intel 82599.
> What make me confused is that we know we can not see the vf 0 & vf 1 directly
> from the host server with "ifconfig", that is to say, vf 0 & vf1 are not a
> real physical interface.

Why vf0 can be seen from 'ifconfig'? 
In our testing, after inserting the ixgbe driver, we can see the VF network devices. 
And for the <interface dev='XX'> part, 'XX' is your VF network device name. 

> I try #: virsh net-define macvtap_passthrough.xml
> #: virsh net-start macvtap_passthrough

> When I try to configure macvtap_passthrough for a VNIC of a VM, the
> virt-manager told : "Can't get vf 0, no such a device".
> When I try from virt-manager: add hardware--->network--->host device
> (macvtap_passthrough:pass_through network), I got error like : "Error adding
> device: xmlParseDoc() failed".
> I guess I can not write like this " <interface dev=’vf0’ /> " in the xml.
> I try to change as below, but the result is same.
> ============================
> <network>
> <name>macvtap_passthrough’</name>
> <forward mode=’passthrough>
> <pf dev=’p2p1’ /> // p2p1 is intel sriov physical nic
> </forward>
> </network>
> ============================

> I don't know how to write correctly. Please help me.
> You can refer to intel document as below.
> Many thanks.
> ==========document from intel========================
> Linux/KVM VM Live Migration (SRIOV And MacVtap)
> By Waseem Ahmad ( waseem.ahmad at intel.com
> In this scenario we are using 3 machines:
>  Server 1: DNS/NFS – nfs.vtt.priv
>  Server 2: Hv1
>  Server3: Hv2
> HV1 and HV2 are Linux/KVM machines. We will get to them in a minute however
> we first must address kvm and nfs.
> NFS:
>  Create a storage area, where both HV1, and HV2 can access it. There are
> several methods available for this (FCOE/ISCSI/NFS). For this write-up use
> nfs.
> Configure NFS:
>  Create a directory on nfs.vtt.priv where you want your storage to be. In
> this case used /home/vmstorage
>  Edit /etc/exports and add the following
> /home/vmstorage 172.0.0.0/1(rw,no_root_squash,sync)
>  Now to /etc/sysconfig/nfs
> Uncomment RPCNFSDARGS=”-N 4”
> This will disable nfs v4. If you don’t do this you will have issues with not
> being able to access the share from within VirtManager.
>  Add all three machines ip addresses to each machines /hosts file.
> MIGRATION WILL NOT WORK WITHOUT FULLY QUALIFIED DOMAIN NAMES.
> KVM:
> On both HV1, and HV2 servers:
>  Edit /etc/selinux/config
> SELINUX=disabled
>  Edit /etc/libvirt/qemu.conf
> Change security_driver=none
>  On HV1 and HV2 start Virtual Machine Manager
>  Double click on localhost(QEMU)
>  Then click on the storage tab at the top of the window that pops up
>  Down in the left hand corner is a box with a + sign in it, click on that. A
> new window will appear entitled Add a New Storage Pool
>  In the name box type vmstorage, then click on the type box and select
> netfs: Network Exported Directory, now click next.
>  You will see the last step of the network Storage Pool Dialog. The first
> option is the target path. This is the path where we will mount our storage
> on the local server. I have chosen to leave this alone.
>  The next option is format, leave this set on auto:
> Host name: nfs.vtt.priv
> Source path: /home/vmstorage
>  Click on finish
>  Repeat the above steps on HV2 server
> Create vms
>  On HV1 server go back to the connection details screen, (this is the one
> that showed up when you double clicked on localhost (qemu), and click on the
> storage tab again.
>  Click on vmstorage then click on new volume at the bottom.
>  A new dialog will appear entitled add a storage volume.
>  In the Name box type vm1
>  In the Max Capacity box type 20000
>  And do the same in the allocation box then click finish.
>  Now you can close the connection details box by click on the x in the
> corner.
>  Now click on the terminal in the corner, right underneath file, and type
> the name of our vm in the box that is entitled Name, vm1 choose how your
> installation media, probably local install media, and click forward. Click
> on use cdrom or dvd, and place a rh6.2 dvd in the dvd player on HV1. Select
> Linux, for the OS type, and Red Hat Enterprise Linux 6 for the version.
> Memory I chose to leave this at its default of 1024, and assigned 1 cpu to
> the guest. Click forward, select “select managed or other existing storage”
> and click the browse button. Click on vmstoarge, and select vm1.img then
> click forward. Then click on finish.
>  We will configure network after we make sure migration between the two
> servers works properly.
>  Now go ahead and install the operating system as you would normally.
> Create networks
> Create a file that looks like the following < there is no support for adding
> a macvtap interface from the gui as of yet, this is the only manual step in
> the process. Create a file named macvtap_passthrough.xml with the following
> contents.
> <network>
> <name>macvtap_passthrough’</name>
> <forward mode=’passthrough>
> <interface dev=’vf0’ />
> <interface dev=’vf1’ />
> .. ..
> </forward>
> </network>
> <network> <name>’macvtap_bridge’</name> <forward mode=’bridge’> <interface
> dev=’p3p1’/> </forward>
> </network>
> Save it and run the following commands:
>  virsh net-define macvtap_passthrough.xml
>  virsh net-start macvtap_passthrough
> Make sure all of your virtual interfaces that you used in the xml file are
> up.
> for i in $(ifconfig –a | awk ‘/eth/ {print $1}’); do ifconfig $i up; done
> Then double click on your vm and click on the big blue i
> On the next screen click on add hardware, then on network, then select
> Virtual network “macvtap_passthrough”
> Then click on finish.
> Start your vm and make sure that the macvtap was created on the host by doing
> ip link | grep ‘macvtap’
> In the vm configure the ip information for the virtio adapter.
> In the virtual machine manager click on file, add connection.
> Then check the connect to remote host fill in the username and hostname, then
> click on connect
> Right click on your VM and select Migrate, select the host you want to
> migrate the machine to, then click on advanced options, check the address
> box, and type the ip address of the machine you want to migrate to, and
> click the migrate button.

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