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

[Matthew Rosato]

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.

>> ---
>>  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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