[libvirt] [PATCH] network: Defer online of macvtap during qemu migration

[Laine Stump]

On 05/13/2014 04:31 PM, Matthew Rosato wrote:
> On 05/05/2014 12:33 PM, Matthew Rosato wrote:
>> On 05/05/2014 12:26 PM, Matthew Rosato wrote:
>>> When generating macvtaps via virNetDevMacVLanCreateWithVPortProfile,
>>> the macvtap device is unconditionally set to the up state.  However,
>>> during migration, this results in a case where both the source and
>>> target system are simultaneously up with the same MAC address.  This
>>> patch defers bringing the target macvtap up until later in the
>>> migration to shrink this window.
>>>
>>> Signed-off-by: Matthew Rosato <mjrosato at linux.vnet.ibm.com>
>> Forgot to mention that this patch is associated with what Wangrui
>> reported here:
>>
>> http://www.redhat.com/archives/libvir-list/2014-March/msg01054.html
>>
>> and follows Viktor's suggested solution mentioned here:
>>
>> http://www.redhat.com/archives/libvir-list/2014-March/msg01654.html
>>
>>
> Ping.

Review coming up. Sorry for the delay. (I'm looking to see if the fix
can be simplified to bring up the macvtap interfaces *always*, rather
than just during migration.)

BTW, there is an open BZ for this:

https://bugzilla.redhat.com/show_bug.cgi?id=1081461


>
>>> ---
>>>  src/qemu/qemu_migration.c   |   18 ++++++++++++++++++
>>>  src/util/virnetdevmacvlan.c |   11 ++++++++---
>>>  2 files changed, 26 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/src/qemu/qemu_migration.c b/src/qemu/qemu_migration.c
>>> index a9f7fea..aee803a 100644
>>> --- a/src/qemu/qemu_migration.c
>>> +++ b/src/qemu/qemu_migration.c
>>> @@ -56,6 +56,7 @@
>>>  #include "virhook.h"
>>>  #include "virstring.h"
>>>  #include "virtypedparam.h"
>>> +#include "virnetdev.h"
>>>
>>>  #define VIR_FROM_THIS VIR_FROM_QEMU
>>>
>>> @@ -4468,6 +4469,8 @@ qemuMigrationFinish(virQEMUDriverPtr driver,
>>>      virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
>>>      virCapsPtr caps = NULL;
>>>      unsigned short port;
>>> +    virDomainNetDefPtr net;
>>> +    size_t i;
>>>
>>>      VIR_DEBUG("driver=%p, dconn=%p, vm=%p, cookiein=%s, cookieinlen=%d, "
>>>                "cookieout=%p, cookieoutlen=%p, flags=%lx, retcode=%d",
>>> @@ -4574,6 +4577,21 @@ qemuMigrationFinish(virQEMUDriverPtr driver,
>>>          }
>>>
>>>          if (!(flags & VIR_MIGRATE_PAUSED) && !(flags & VIR_MIGRATE_OFFLINE)) {
>>> +            /* Macvtaps were previously left offline, bring them online now */
>>> +            for (i = 0; i < vm->def->nnets; i++) {
>>> +                net = vm->def->nets[i];
>>> +                if (virDomainNetGetActualType(net) == VIR_DOMAIN_NET_TYPE_DIRECT) {
>>> +                    if (virNetDevSetOnline(net->ifname, true) < 0) {
>>> +                        ignore_value(virNetDevVPortProfileDisassociate(net->ifname,
>>> +                                                                       virDomainNetGetActualVirtPortProfile(net),
>>> +                                                                       &net->mac,
>>> +                                                                       virDomainNetGetActualDirectDev(net),
>>> +                                                                       -1,
>>> +                                                                       VIR_NETDEV_VPORT_PROFILE_OP_MIGRATE_IN_FINISH));
>>> +                        ignore_value(virNetDevMacVLanDelete(net->ifname));
>>> +                    }
>>> +                }
>>> +            }
>>>              /* run 'cont' on the destination, which allows migration on qemu
>>>               * >= 0.10.6 to work properly.  This isn't strictly necessary on
>>>               * older qemu's, but it also doesn't hurt anything there
>>> diff --git a/src/util/virnetdevmacvlan.c b/src/util/virnetdevmacvlan.c
>>> index 7bbf540..3da845b 100644
>>> --- a/src/util/virnetdevmacvlan.c
>>> +++ b/src/util/virnetdevmacvlan.c
>>> @@ -898,9 +898,14 @@ int virNetDevMacVLanCreateWithVPortProfile(const char *tgifname,
>>>          goto link_del_exit;
>>>      }
>>>
>>> -    if (virNetDevSetOnline(cr_ifname, true) < 0) {
>>> -        rc = -1;
>>> -        goto disassociate_exit;
>>> +    /* If this device is being created as part of an inbound
>>> +     * migration, leave the device offline for now.
>>> +     */
>>> +    if (vmOp != VIR_NETDEV_VPORT_PROFILE_OP_MIGRATE_IN_START) {
>>> +        if (virNetDevSetOnline(cr_ifname, true) < 0) {
>>> +            rc = -1;
>>> +            goto disassociate_exit;
>>> +        }
>>>      }
>>>
>>>      if (withTap) {
>>>
>> --
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>>
>>
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