On Mon, 2011-04-25 at 10:41 -0600, David Ahern wrote: > > On 04/25/11 10:37, Alex Williamson wrote: > > On Mon, 2011-04-25 at 10:28 -0600, David Ahern wrote: > >> Running qemu-kvm.git as of today (ffce28f, April 18, 2011) the virtual > >> function passed to the VM is losing its assigned mac address. That is, > >> prior to launching qemu-kvm, the following command is run to set the MAC > >> address: > >> > >> ip link set dev eth2 vf 0 mac 02:12:34:56:79:20 > >> > >> Yet, when the VM boots the MAC address is random which is what happens > >> when the VF is reset. Looking through the commit logs between 0.13.0 -- > >> the version in Fedora 14 -- and latest git I found the following: > >> > >> commit d9488459ff2ab113293586c1c36b1679bb15deee > >> Author: Alex Williamson <alex.williamson@xxxxxxxxxx> > >> Date: Thu Mar 17 15:24:31 2011 -0600 > >> > >> device-assignment: Reset device on system reset > >> > >> On system reset, we currently try to quiesce DMA by clearing the > >> command register. This assumes that nothing re-enables bus master > >> support without first de-programming the device. Use a bigger > >> hammer to help the guest not shoot itself by issuing a function > >> reset via sysfs on each system reset. > >> > >> Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx> > >> Acked-by: Chris Wright <chrisw@xxxxxxxxxx> > >> Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx> > >> > >> > >> Is this the cause of the MAC address reset and is this behavior intended? > > > > Ugh, I hope not, it's certainly not an intended side effect. Can you > > see if the problem still happens if you revert this patch? If it does, > > I commented out the write() in the reset function and indeed the mac > address was not reset on VM boot. Ok, here's what I see on my system: # modprobe igbvf # dmesg | grep "igbvf 0000\:01\:11.5\: Address\:" igbvf 0000:01:11.5: Address: d2:c8:17:d6:97:f7 # modprobe -r igbvf # echo 1 > /sys/bus/pci/devices/0000:01:11.5/reset # modprobe igbvf # dmesg | grep "igbvf 0000\:01\:11.5\: Address\:" igbvf 0000:01:11.5: Address: d2:c8:17:d6:97:f7 igbvf 0000:01:11.5: Address: 4e:ee:2a:d8:12:7c So yes, it does change. However, if I set the VF mac instead of using a randomly generated one, I get: # modprobe -r igbvf # ip link set eth2 vf 6 mac 02:00:10:91:73:01 # modprobe igbvf # dmesg | grep "igbvf 0000\:01\:11.5\: Address\:" igbvf 0000:01:11.5: Address: d2:c8:17:d6:97:f7 igbvf 0000:01:11.5: Address: 4e:ee:2a:d8:12:7c igbvf 0000:01:11.5: Address: 02:00:10:91:73:01 # modprobe -r igbvf # echo 1 > /sys/bus/pci/devices/0000:01:11.5/reset # modprobe igbvf # dmesg | grep "igbvf 0000\:01\:11.5\: Address\:" igbvf 0000:01:11.5: Address: d2:c8:17:d6:97:f7 igbvf 0000:01:11.5: Address: 4e:ee:2a:d8:12:7c igbvf 0000:01:11.5: Address: 02:00:10:91:73:01 igbvf 0000:01:11.5: Address: 02:00:10:91:73:01 So now it sticks. You're going to get random mac addresses on the VFs every time you reload the igb driver (ie. ever boot) anyway (at least with these sr-iov cards), so if you need consistent macs, they probably need to be set before launching the VM anyway. Thanks, Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
