Re: [Qemu-devel] [PATCH V2] migration: expose qemu_announce_self() via qmp

[Germano Veit Michel <germano@redhat.com>]

Hi guys,

Finally got some time to prepare V3.

First of all Dave's trick is really useful to test it:

./x86_64-softmmu/qemu-system-x86_64 -nographic -nodefaults -netdev
user,id=netuser -object filter-dump,id=dump,netdev=netuser,file=foo2
-device e1000,netdev=netuser,mac=00:11:22:33:44:55 -monitor stdio
QEMU 2.8.91 monitor - type 'help' for more information
(qemu) announce-self
(qemu) announce-self
(qemu) qemu-system-x86_64: terminating on signal 2

tshark -r foo2 | grep RARP
    1   0.000000 Cimsys_33:44:55 → Broadcast    RARP 60 Who is
00:11:22:33:44:55? Tell 00:11:22:33:44:55
    2   0.050017 Cimsys_33:44:55 → Broadcast    RARP 60 Who is
00:11:22:33:44:55? Tell 00:11:22:33:44:55
    3   0.200077 Cimsys_33:44:55 → Broadcast    RARP 60 Who is
00:11:22:33:44:55? Tell 00:11:22:33:44:55
    4   0.450112 Cimsys_33:44:55 → Broadcast    RARP 60 Who is
00:11:22:33:44:55? Tell 00:11:22:33:44:55
    5   0.800090 Cimsys_33:44:55 → Broadcast    RARP 60 Who is
00:11:22:33:44:55? Tell 00:11:22:33:44:55
   13   5.583887 Cimsys_33:44:55 → Broadcast    RARP 60 Who is
00:11:22:33:44:55? Tell 00:11:22:33:44:55
   14   5.633079 Cimsys_33:44:55 → Broadcast    RARP 60 Who is
00:11:22:33:44:55? Tell 00:11:22:33:44:55
   15   5.783152 Cimsys_33:44:55 → Broadcast    RARP 60 Who is
00:11:22:33:44:55? Tell 00:11:22:33:44:55
   16   6.033130 Cimsys_33:44:55 → Broadcast    RARP 60 Who is
00:11:22:33:44:55? Tell 00:11:22:33:44:55
   17   6.383144 Cimsys_33:44:55 → Broadcast    RARP 60 Who is
00:11:22:33:44:55? Tell 00:11:22:33:44:55

Now for qtest:

It is compiling and running my test:

  [....]
  CC      tests/qmp-net-test.o
  LINK    tests/qmp-net-test
  [....]
  GTESTER check-qtest-x86_64

/bin/sh -c printf "  %-7s %s\n" "GTESTER" "check-qtest-x86_64" &&
QTEST_QEMU_BINARY=x86_64-softmmu/qemu-system-x86_64 QTEST_QEMU_IMG=qemu-img
MALLOC_PERTURB_=${MALLOC_PERTURB_:-$((RANDOM % 255 + 1))} gtester -k -q
-m=quick [.....] tests/qmp-net-test [....]

Weird is... is the test qemu running without NICs?

x86_64-softmmu/qemu-system-x86_64 -qtest unix:/tmp/qtest-17545.sock,nowait
-qtest-log /dev/null -qmp unix:/tmp/qtest-17545.qmp,nowait -machine
accel=qtest -display none -M q35,accel=tcg -chardev
file,id=serial0,path=/tmp/qtest-boot-serial-HYHJ2e -no-shutdown -serial
chardev:serial0 -device sga

I was looking at this
http://events.linuxfoundation.org/sites/events/files/slides/Testing%20QEMU%20emulated%20devices%20using%20qtest.pdf
and it's pretty helpful. But I have no clues on how to actually check if
the RARP packets really go out on each NIC. Any idea on how to implement
this or is the smoke test enough?

Thanks

On Tue, Mar 28, 2017 at 2:31 AM, Dr. David Alan Gilbert <dgilbert@redhat.com
> wrote:

> * Markus Armbruster (armbru@redhat.com) wrote:
> > "Dr. David Alan Gilbert" <dgilbert@redhat.com> writes:
> >
> > > * Germano Veit Michel (germano@redhat.com) wrote:
> > >> qemu_announce_self() is triggered by qemu at the end of migrations
> > >> to update the network regarding the path to the guest l2addr.
> > >>
> > >> however it is also useful when there is a network change such as
> > >> an active bond slave swap. Essentially, it's the same as a migration
> > >> from a network perspective - the guest moves to a different point
> > >> in the network topology.
> > >>
> > >> this exposes the function via qmp.
> > >
> > > Markus: Since you're asking for tests for qmp commands; how would you
> > > test this?
> >
> > Good question, as tests/ isn't exactly full of examples you could crib.
> >
> > Let me look at the patch...
> >
> > > Jason: Does this look OK from the networking side of things?
> > >
> > >> Signed-off-by: Germano Veit Michel <germano@redhat.com>
> > >> ---
> > >>  include/migration/vmstate.h |  5 +++++
> > >>  migration/savevm.c          | 30 +++++++++++++++++++-----------
> > >>  qapi-schema.json            | 18 ++++++++++++++++++
> > >>  3 files changed, 42 insertions(+), 11 deletions(-)
> > >>
> > >> diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
> > >> index 63e7b02..a08715c 100644
> > >> --- a/include/migration/vmstate.h
> > >> +++ b/include/migration/vmstate.h
> > >> @@ -1042,6 +1042,11 @@ int64_t self_announce_delay(int round)
> > >>      return 50 + (SELF_ANNOUNCE_ROUNDS - round - 1) * 100;
> > >>  }
> > >>
> > >> +struct AnnounceRound {
> > >> +    QEMUTimer *timer;
> > >> +    int count;
> > >> +};
> > >> +
> > >>  void dump_vmstate_json_to_file(FILE *out_fp);
> > >>
> > >>  #endif
> > >> diff --git a/migration/savevm.c b/migration/savevm.c
> > >> index 5ecd264..44e196b 100644
> > >> --- a/migration/savevm.c
> > >> +++ b/migration/savevm.c
> > >> @@ -118,29 +118,37 @@ static void qemu_announce_self_iter(NICState
> > >> *nic, void *opaque)
> > >>      qemu_send_packet_raw(qemu_get_queue(nic), buf, len);
> > >>  }
> > >>
> > >> -
> > >>  static void qemu_announce_self_once(void *opaque)
> > >>  {
> > >> -    static int count = SELF_ANNOUNCE_ROUNDS;
> > >> -    QEMUTimer *timer = *(QEMUTimer **)opaque;
> > >> +    struct AnnounceRound *round = opaque;
> > >>
> > >>      qemu_foreach_nic(qemu_announce_self_iter, NULL);
> > >>
> > >> -    if (--count) {
> > >> +    round->count--;
> > >> +    if (round->count) {
> > >>          /* delay 50ms, 150ms, 250ms, ... */
> > >> -        timer_mod(timer, qemu_clock_get_ms(QEMU_CLOCK_REALTIME) +
> > >> -                  self_announce_delay(count));
> > >> +        timer_mod(round->timer, qemu_clock_get_ms(QEMU_CLOCK_REALTIME)
> +
> > >> +                  self_announce_delay(round->count));
> > >>      } else {
> > >> -            timer_del(timer);
> > >> -            timer_free(timer);
> > >> +            timer_del(round->timer);
> > >> +            timer_free(round->timer);
> > >> +            g_free(round);
> > >>      }
> > >>  }
> > >>
> > >>  void qemu_announce_self(void)
> > >>  {
> > >> -    static QEMUTimer *timer;
> > >> -    timer = timer_new_ms(QEMU_CLOCK_REALTIME,
> qemu_announce_self_once, &timer);
> > >> -    qemu_announce_self_once(&timer);
> > >> +    struct AnnounceRound *round = g_malloc(sizeof(struct
> AnnounceRound));
> > >
> > > I prefer g_new0 - i.e.
> > >    struct AnnounceRound *round = g_new0(struct AnnounceRound, 1)
> > >
> > >> +    if (!round)
> > >> +        return;
> > >> +    round->count = SELF_ANNOUNCE_ROUNDS;
> > >> +    round->timer = timer_new_ms(QEMU_CLOCK_REALTIME,
> > >> qemu_announce_self_once, round);
> > >
> > > An odd line break?
> > >
> > >> +    qemu_announce_self_once(round);
> > >> +}
> > >> +
> > >> +void qmp_announce_self(Error **errp)
> > >> +{
> > >> +    qemu_announce_self();
> > >>  }
> > >>
> > >>  /***********************************************************/
> > >> diff --git a/qapi-schema.json b/qapi-schema.json
> > >> index baa0d26..0d9bffd 100644
> > >> --- a/qapi-schema.json
> > >> +++ b/qapi-schema.json
> > >> @@ -6080,3 +6080,21 @@
> > >>  #
> > >>  ##
> > >>  { 'command': 'query-hotpluggable-cpus', 'returns':
> ['HotpluggableCPU'] }
> > >> +
> > >> +##
> > >> +# @announce-self:
> > >> +#
> > >> +# Trigger generation of broadcast RARP frames to update network
> switches.
> > >> +# This can be useful when network bonds fail-over the active slave.
> > >> +#
> > >> +# Arguments: None.
> >
> > Please drop this line.
> >
> > >> +#
> > >> +# Example:
> > >> +#
> > >> +# -> { "execute": "announce-self" }
> > >> +# <- { "return": {} }
> > >> +#
> > >> +# Since: 2.9
> > >> +##
> > >> +{ 'command': 'announce-self' }
> > >> +
> >
> > From QMP's point of view, this command is as simple as they get: no
> > arguments, no return values, no errors.
> >
> > I think a basic smoke test would do: try the command, check no magic
> > smoke comes out.  Untested sketch adapted from qmp-test.c:
> >
> >     /*
> >      * Test cases for network-related QMP commands
> >      *
> >      * Copyright (c) 2017 Red Hat Inc.
> >      *
> >      * Authors:
> >      *  Markus Armbruster <armbru@redhat.com>,
> >      *
> >      * This work is licensed under the terms of the GNU GPL, version 2
> or later.
> >      * See the COPYING file in the top-level directory.
> >      */
> >
> >     #include "qemu/osdep.h"
> >     #include "libqtest.h"
> >     #include "qapi/error.h"
> >
> >     const char common_args[] = "-nodefaults -machine none";
> >
> >     static void test_qmp_announce_self(void)
> >     {
> >         QDict *resp, *ret;
> >
> >         qtest_start(common_args);
> >
> >         resp = qmp("{ 'execute': 'qmp_capabilities' }");
> >         ret = qdict_get_qdict(resp, "return");
> >         g_assert(ret && !qdict_size(ret));
> >         QDECREF(resp);
> >
> >         qtest_end();
> >     }
> >
> >     int main(int argc, char *argv[])
> >     {
> >         g_test_init(&argc, &argv, NULL);
> >
> >         qtest_add_func("qmp/net/announce_self", test_qmp_announce_self);
> >
> >         return g_test_run();
> >     }
> >
> > If you want to go the extra mile: is there a way to set up networking so
> > you can observe the RARPs this should trigger?
>
> I've been fiddling with the RARP code for other changes and noticed you
> can do:
>
> ./x86_64-softmmu/qemu-system-x86_64 -nographic -nodefaults -netdev
> user,id=netuser -object filter-dump,id=dump,netdev=netuser,file=foo2
> -device e1000,netdev=netuser,mac=00:11:22:33:44:55 -monitor stdio
>
> (Thanks to Thomas for helping explain filter-dump).
>
> So those land in foo2 as a pcap file.
>
> Dave
>
> > I'd call this qmp-net-test.  Add to Makefile.include exactly like
> > qmp-test.
> >
> > Test cases for existing networking-related QMP commands should be added,
> > but not in this patch, and not necessarily by you.
> >
> > Alternatively, have a more general test program for networking stuff,
> > and make this one of its test cases.  Your choice.
> >
> > Hope this helps!
> >
> > >
> > > Please wire hmp up as well (see hmp-commands.hx).
> > >
> > > Dave
> > >
> > >> --
> > >> 2.9.3
> > > --
> > > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> --
> Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
>



-- 
Germano Veit Michel <germano@redhat.com>
Senior Software Maintenance Engineer, Virtualization, Red Hat