From 16ba1d0258765d9c3b5e2da666ed6d4d933e26d9 Mon Sep 17 00:00:00 2001

Message-Id: <16ba1d0258765d9c3b5e2da666ed6d4d933e26d9@dist-git>

From: Laine Stump <laine@redhat.com>

Date: Thu, 30 Jan 2020 14:12:41 -0500

Subject: [PATCH] qemu: support interface <teaming> functionality

MIME-Version: 1.0

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Content-Transfer-Encoding: 8bit

The QEMU driver uses the 

persistent='blah'/> element to setup a "failover" pair of devices -

the persistent device must be a virtio emulated NIC, with the only

extra configuration being the addition of ",failover=on" to the device

commandline, and the transient device must be a hostdev NIC

(<interface type='hostdev'> or <interface type='network'> with a

network that is a pool of SRIOV VFs) where the extra configuration is

the addition of ",failover_pair_id=$aliasOfVirtio" to the device

commandline. These new options are supported in QEMU 4.2.0 and later.

Extra qemu-specific validation is added to ensure that the device

type/model is appropriate and that the qemu binary supports these

commandline options.

The result of this will be:

1) The virtio device presented to the guest will have an extra bit set

in its PCI capabilities indicating that it can be used as a failover

backup device. The virtio guest driver will need to be equipped to do

something with this information - this is included in the Linux

virtio-net driver in kernel 4.18 and above (and also backported to

some older distro kernels). Unfortunately there is no way for libvirt

to learn whether or not the guest driver supports failover - if it

doesn't then the extra PCI capability will be ignored and the guest OS

will just see two independent devices. (NB: the current virtio guest

driver also requires that the MAC addresses of the two NICs match in

order to pair them into a bond).

2) When a migration is requested, QEMu will automatically unplug the

transient/hostdev NIC from the guest on the source host before

starting migration, and automatically re-plug a similar device after

restarting the guest CPUs on the destination host. While the transient

NIC is unplugged, all network traffic will go through the

persistent/virtio device, but when the hostdev NIC is plugged in, it

will get all the traffic. This means that in normal circumstances the

guest gets the performance advantage of vfio-assigned "real hardware"

networking, but it can still be migrated with the only downside being

a performance penalty (due to using an emulated NIC) during the

migration.

Signed-off-by: Laine Stump <laine@redhat.com>

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

(cherry picked from commit eb9f6cc4b3464707cf689fda9812e5129003bf27)

https://bugzilla.redhat.com/1693587

Signed-off-by: Laine Stump <laine@redhat.com>

Message-Id: <20200130191244.24174-4-laine@redhat.com>

Reviewed-by: Jiri Denemark <jdenemar@redhat.com>

---

 src/qemu/qemu_command.c                       |  9 +++++

 src/qemu/qemu_domain.c                        | 36 +++++++++++++++--

 .../qemuxml2argvdata/net-virtio-teaming.args  | 40 +++++++++++++++++++

 tests/qemuxml2argvtest.c                      |  4 ++

 4 files changed, 86 insertions(+), 3 deletions(-)

 create mode 100644 tests/qemuxml2argvdata/net-virtio-teaming.args

diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c

index 7a184c229e..d144855b0d 100644

--- a/src/qemu/qemu_command.c

+++ b/src/qemu/qemu_command.c

@@ -3833,6 +3833,8 @@ qemuBuildNicDevStr(virDomainDefPtr def,

         }

         virBufferAsprintf(&buf, ",host_mtu=%u", net->mtu);

     }

+    if (usingVirtio && net->teaming.type == VIR_DOMAIN_NET_TEAMING_TYPE_PERSISTENT)

+       virBufferAddLit(&buf, ",failover=on");

     virBufferAsprintf(&buf, ",netdev=host%s", net->info.alias);

     virBufferAsprintf(&buf, ",id=%s", net->info.alias);

@@ -4704,6 +4706,13 @@ qemuBuildPCIHostdevDevStr(const virDomainDef *def,

     if (qemuBuildRomStr(&buf, dev->info) < 0)

         return NULL;

+    if (dev->parentnet &&

+        dev->parentnet->teaming.type == VIR_DOMAIN_NET_TEAMING_TYPE_TRANSIENT &&

+        dev->parentnet->teaming.persistent) {

+        virBufferAsprintf(&buf,  ",failover_pair_id=%s",

+                          dev->parentnet->teaming.persistent);

+    }

+

     return virBufferContentAndReset(&buf;;

 }

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c

index 91a9f0481b..e37404340f 100644

--- a/src/qemu/qemu_domain.c

+++ b/src/qemu/qemu_domain.c

@@ -6391,12 +6391,20 @@ qemuDomainValidateActualNetDef(const virDomainNetDef *net,

         return -1;

     }

+    if (net->teaming.type == VIR_DOMAIN_NET_TEAMING_TYPE_TRANSIENT &&

+        actualType != VIR_DOMAIN_NET_TYPE_HOSTDEV) {

+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,

+                       _("interface %s - teaming transient device must be type='hostdev', not '%s'"),

+                       macstr, virDomainNetTypeToString(actualType));

+        return -1;

+    }

     return 0;

 }

 static int

-qemuDomainDeviceDefValidateNetwork(const virDomainNetDef *net)

+qemuDomainDeviceDefValidateNetwork(const virDomainNetDef *net,

+                                   virQEMUCapsPtr qemuCaps)

 {

     bool hasIPv4 = false;

     bool hasIPv6 = false;

@@ -6481,7 +6489,29 @@ qemuDomainDeviceDefValidateNetwork(const virDomainNetDef *net)

         return -1;

     }

-    if (net->coalesce && !qemuDomainNetSupportsCoalesce(net->type)) {

+    if (net->teaming.type != VIR_DOMAIN_NET_TEAMING_TYPE_NONE &&

+        !virQEMUCapsGet(qemuCaps, QEMU_CAPS_VIRTIO_NET_FAILOVER)) {

+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s",

+                       _("virtio-net failover (teaming) is not supported with this QEMU binary"));

+        return -1;

+    }

+    if (net->teaming.type == VIR_DOMAIN_NET_TEAMING_TYPE_PERSISTENT

+        && !virDomainNetIsVirtioModel(net)) {

+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,

+                       _("virtio-net teaming persistent interface must be <model type='virtio'/>, not '%s'"),

+                       virDomainNetGetModelString(net));

+        return -1;

+    }

+    if (net->teaming.type == VIR_DOMAIN_NET_TEAMING_TYPE_TRANSIENT &&

+        net->type != VIR_DOMAIN_NET_TYPE_HOSTDEV &&

+        net->type != VIR_DOMAIN_NET_TYPE_NETWORK) {

+        virReportError(VIR_ERR_CONFIG_UNSUPPORTED,

+                       _("virtio-net teaming transient interface must be type='hostdev', not '%s'"),

+                       virDomainNetTypeToString(net->type));

+        return -1;

+    }

+

+   if (net->coalesce && !qemuDomainNetSupportsCoalesce(net->type)) {

         virReportError(VIR_ERR_CONFIG_UNSUPPORTED,

                        _("coalesce settings on interface type %s are not supported"),

                        virDomainNetTypeToString(net->type));

@@ -8377,7 +8407,7 @@ qemuDomainDeviceDefValidate(const virDomainDeviceDef *dev,

     switch ((virDomainDeviceType)dev->type) {

     case VIR_DOMAIN_DEVICE_NET:

-        ret = qemuDomainDeviceDefValidateNetwork(dev->data.net);

+        ret = qemuDomainDeviceDefValidateNetwork(dev->data.net, qemuCaps);

         break;

     case VIR_DOMAIN_DEVICE_CHR:

diff --git a/tests/qemuxml2argvdata/net-virtio-teaming.args b/tests/qemuxml2argvdata/net-virtio-teaming.args

new file mode 100644

index 0000000000..19e7260843

--- /dev/null

+++ b/tests/qemuxml2argvdata/net-virtio-teaming.args

@@ -0,0 +1,40 @@

+LC_ALL=C \

+PATH=/bin \

+HOME=/tmp/lib/domain--1-QEMUGuest1 \

+USER=test \

+LOGNAME=test \

+XDG_DATA_HOME=/tmp/lib/domain--1-QEMUGuest1/.local/share \

+XDG_CACHE_HOME=/tmp/lib/domain--1-QEMUGuest1/.cache \

+XDG_CONFIG_HOME=/tmp/lib/domain--1-QEMUGuest1/.config \

+QEMU_AUDIO_DRV=none \

+/usr/bin/qemu-system-i386 \

+-name QEMUGuest1 \

+-S \

+-machine pc,accel=tcg,usb=off,dump-guest-core=off \

+-m 214 \

+-realtime mlock=off \

+-smp 1,sockets=1,cores=1,threads=1 \

+-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \

+-display none \

+-no-user-config \

+-nodefaults \

+-chardev socket,id=charmonitor,path=/tmp/lib/domain--1-QEMUGuest1/monitor.sock,\

+server,nowait \

+-mon chardev=charmonitor,id=monitor,mode=control \

+-rtc base=utc \

+-no-shutdown \

+-no-acpi \

+-usb \

+-drive file=/dev/HostVG/QEMUGuest1,format=raw,if=none,id=drive-ide0-0-0 \

+-device ide-hd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1 \

+-netdev user,id=hostua-backup0 \

+-device virtio-net-pci,failover=on,netdev=hostua-backup0,id=ua-backup0,\

+mac=00:11:22:33:44:55,bus=pci.0,addr=0x3 \

+-netdev user,id=hostua-backup1 \

+-device virtio-net-pci,failover=on,netdev=hostua-backup1,id=ua-backup1,\

+mac=66:44:33:22:11:00,bus=pci.0,addr=0x4 \

+-device vfio-pci,host=0000:03:07.1,id=hostdev0,bus=pci.0,addr=0x5,\

+failover_pair_id=ua-backup0 \

+-device vfio-pci,host=0000:03:07.2,id=hostdev1,bus=pci.0,addr=0x6,\

+failover_pair_id=ua-backup1 \

+-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x7

diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c

index b923590930..4d26fe0b55 100644

--- a/tests/qemuxml2argvtest.c

+++ b/tests/qemuxml2argvtest.c

@@ -1308,6 +1308,10 @@ mymain(void)

             QEMU_CAPS_VIRTIO_NET_RX_QUEUE_SIZE,

             QEMU_CAPS_VIRTIO_NET_TX_QUEUE_SIZE);

     DO_TEST_PARSE_ERROR("net-virtio-rxqueuesize-invalid-size", NONE);

+    DO_TEST("net-virtio-teaming",

+            QEMU_CAPS_VIRTIO_NET_FAILOVER,

+            QEMU_CAPS_DEVICE_VFIO_PCI);

+    DO_TEST_PARSE_ERROR("net-virtio-teaming", NONE);

     DO_TEST("net-eth", NONE);

     DO_TEST("net-eth-ifname", NONE);

     DO_TEST("net-eth-names", NONE);

-- 

2.25.0