[libvirt] [PATCH 2/2] qemu: change macvtap multicast list in response to NIC_RX_FILTER_CHANGED

[Laine Stump]

On 10/06/2014 05:37 PM, akrowiak at linux.vnet.ibm.com wrote:
> From: Tony Krowiak <akrowiak at linux.vnet.ibm.com>
>
> This patch adds functionality to processNicRxFilterChangedEvent().
> The old and new multicast lists are compared and the filters in
> the macvtap are programmed to match the guest's filters.
>
> Signed-off-by: Tony Krowiak <akrowiak at linux.vnet.ibm.com>
> ---
>  src/qemu/qemu_driver.c |  138 +++++++++++++++++++++++++++++++++++++++--------
>  1 files changed, 114 insertions(+), 24 deletions(-)
>
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index 4e2b356..7ff9c38 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -4147,6 +4147,106 @@ processDeviceDeletedEvent(virQEMUDriverPtr driver,
>  
>  
>  static void
> +syncNicRxFilterMacAddr(char *ifname, virNetDevRxFilterPtr guestFilter,
> +                       virNetDevRxFilterPtr hostFilter)
> +{
> +    char newMacStr[VIR_MAC_STRING_BUFLEN];
> +
> +    if (virMacAddrCmp(&hostFilter->mac, &guestFilter->mac)) {
> +        virMacAddrFormat(&guestFilter->mac, newMacStr);
> +
> +        /* set new MAC address from guest to associated macvtap device */
> +        if (virNetDevSetMAC(ifname, &guestFilter->mac)) {
> +            VIR_WARN("Couldn't set new MAC address %s to device %s "
> +                     "while responding to NIC_RX_FILTER_CHANGED",
> +                     newMacStr, ifname);
> +        } else {
> +            VIR_DEBUG("device %s MAC address set to %s", ifname, newMacStr);
> +        }
> +    }
> +}
> +
> +
> +static void
> +syncNicRxFilterGuestMulticast(char *ifname, virNetDevRxFilterPtr guestFilter,
> +                              virNetDevRxFilterPtr hostFilter)
> +{
> +    size_t i, j;
> +    bool found;
> +    char macstr[VIR_MAC_STRING_BUFLEN];
> +
> +    for (i = 0; i < guestFilter->multicast.nTable; i++) {
> +        found = false;
> +
> +        for (j = 0; j < hostFilter->multicast.nTable; j++) {
> +            if (virMacAddrCmp(&guestFilter->multicast.table[i],
> +                              &hostFilter->multicast.table[j]) == 0) {
> +                found = true;
> +                break;
> +            }
> +        }
> +
> +        if (!found) {
> +            virMacAddrFormat(&guestFilter->multicast.table[i], macstr);
> +
> +            if (virNetDevAddMulti(ifname, &guestFilter->multicast.table[i])) {
> +                VIR_WARN("Couldn't add new multicast MAC address %s to "
> +                         "device %s while responding to NIC_RX_FILTER_CHANGED",
> +                         macstr, ifname);
> +            } else {
> +                VIR_DEBUG("Added multicast MAC %s to %s interface",
> +                          macstr, ifname);
> +            }
> +        }
> +    }
> +}
> +
> +
> +static void
> +syncNicRxFilterHostMulticast(char *ifname, virNetDevRxFilterPtr guestFilter,
> +                             virNetDevRxFilterPtr hostFilter)
> +{
> +    size_t i, j;
> +    bool found;
> +    char macstr[VIR_MAC_STRING_BUFLEN];
> +
> +    for (i = 0; i < hostFilter->multicast.nTable; i++) {
> +        found = false;
> +
> +        for (j = 0; j < guestFilter->multicast.nTable; j++) {
> +            if (virMacAddrCmp(&hostFilter->multicast.table[i],
> +                              &guestFilter->multicast.table[j]) == 0) {
> +                found = true;
> +                break;
> +            }
> +        }
> +
> +        if (!found) {
> +            virMacAddrFormat(&hostFilter->multicast.table[i], macstr);
> +
> +            if (virNetDevDelMulti(ifname, &hostFilter->multicast.table[i])) {
> +                VIR_WARN("Couldn't delete multicast MAC address %s from "
> +                         "device %s while responding to NIC_RX_FILTER_CHANGED",
> +                         macstr, ifname);
> +            } else {
> +                VIR_DEBUG("Deleted multicast MAC %s from %s interface",
> +                          macstr, ifname);
> +            }
> +        }
> +    }
> +}
> +
> +
> +static void
> +syncNicRxFilterMulticast(char *ifname,
> +                         virNetDevRxFilterPtr guestFilter,
> +                         virNetDevRxFilterPtr hostFilter)
> +{
> +    syncNicRxFilterGuestMulticast(ifname, guestFilter, hostFilter);
> +    syncNicRxFilterHostMulticast(ifname, guestFilter, hostFilter);

Interesting method. I had planned to sort both lists, then do a single
loop that went through the two in parallel, deleting/adding from the
host interface filter at each step as necessary. Yours works, too,
though. :-)

ACK to this patch. I'll push it along with 1/2 once a new eversion of
that patch has gotten ACK.

BTW, once we're programming the multicast filter, do we need to set any
other mode of the macvtap device in order for this to have a positive
impact on performance? Or does multicast simply not work properly
without this patch (I don't use multicast for anything, and don't have
any tests setup to use multicast).

> +}
> +
> +static void
>  processNicRxFilterChangedEvent(virQEMUDriverPtr driver,
>                                 virDomainObjPtr vm,
>                                 char *devAlias)
> @@ -4155,9 +4255,8 @@ processNicRxFilterChangedEvent(virQEMUDriverPtr driver,
>      qemuDomainObjPrivatePtr priv = vm->privateData;
>      virDomainDeviceDef dev;
>      virDomainNetDefPtr def;
> -    virNetDevRxFilterPtr filter = NULL;
> -    virMacAddr oldMAC;
> -    char newMacStr[VIR_MAC_STRING_BUFLEN];
> +    virNetDevRxFilterPtr guestFilter = NULL;
> +    virNetDevRxFilterPtr hostFilter = NULL;
>      int ret;
>  
>      VIR_DEBUG("Received NIC_RX_FILTER_CHANGED event for device %s "
> @@ -4202,37 +4301,27 @@ processNicRxFilterChangedEvent(virQEMUDriverPtr driver,
>                "device %s in domain %s", def->info.alias, vm->def->name);
>  
>      qemuDomainObjEnterMonitor(driver, vm);
> -    ret = qemuMonitorQueryRxFilter(priv->mon, devAlias, &filter);
> +    ret = qemuMonitorQueryRxFilter(priv->mon, devAlias, &guestFilter);
>      qemuDomainObjExitMonitor(driver, vm);
>      if (ret < 0)
>          goto endjob;
>  
> -    virMacAddrFormat(&filter->mac, newMacStr);
> -
>      if (virDomainNetGetActualType(def) == VIR_DOMAIN_NET_TYPE_DIRECT) {
>  
> -        /* For macvtap connections, set the macvtap device's MAC
> -         * address to match that of the guest device.
> -         */
> -
> -        if (virNetDevGetMAC(def->ifname, &oldMAC) < 0) {
> -            VIR_WARN("Couldn't get current MAC address of device %s "
> +        if (virNetDevGetRxFilter(def->ifname, &hostFilter)) {
> +            VIR_WARN("Couldn't get current RX filter for device %s "
>                       "while responding to NIC_RX_FILTER_CHANGED",
>                       def->ifname);
>              goto endjob;
>          }
>  
> -        if (virMacAddrCmp(&oldMAC, &filter->mac)) {
> -            /* set new MAC address from guest to associated macvtap device */
> -            if (virNetDevSetMAC(def->ifname, &filter->mac) < 0) {
> -                VIR_WARN("Couldn't set new MAC address %s to device %s "
> -                         "while responding to NIC_RX_FILTER_CHANGED",
> -                         newMacStr, def->ifname);
> -            } else {
> -                VIR_DEBUG("device %s MAC address set to %s",
> -                          def->ifname, newMacStr);
> -            }
> -        }
> +        /* For macvtap connections, set the following macvtap network device
> +         * attributes to match those of the guest network device:
> +         * - MAC address
> +         * - Multicast MAC address table
> +         */
> +        syncNicRxFilterMacAddr(def->ifname, guestFilter, hostFilter);
> +        syncNicRxFilterMulticast(def->ifname, guestFilter, hostFilter);
>      }
>  
>   endjob:
> @@ -4242,7 +4331,8 @@ processNicRxFilterChangedEvent(virQEMUDriverPtr driver,
>      ignore_value(qemuDomainObjEndJob(driver, vm));
>  
>   cleanup:
> -    virNetDevRxFilterFree(filter);
> +    virNetDevRxFilterFree(hostFilter);
> +    virNetDevRxFilterFree(guestFilter);
>      VIR_FREE(devAlias);
>      virObjectUnref(cfg);
>  }