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RE: [PATCH V3] net/colo: check vnet_hdr_support flag when using virtio-n


From: Zhang, Chen
Subject: RE: [PATCH V3] net/colo: check vnet_hdr_support flag when using virtio-net
Date: Wed, 20 Oct 2021 06:19:08 +0000


> -----Original Message-----
> From: Jason Wang <jasowang@redhat.com>
> Sent: Wednesday, October 20, 2021 11:13 AM
> To: Zhang, Chen <chen.zhang@intel.com>
> Cc: Eric Blake <eblake@redhat.com>; Markus Armbruster
> <armbru@redhat.com>; qemu-dev <qemu-devel@nongnu.org>; Li Zhijian
> <lizhijian@cn.fujitsu.com>; Lukas Straub <lukasstraub2@web.de>
> Subject: Re: [PATCH V3] net/colo: check vnet_hdr_support flag when using
> virtio-net
> 
> On Wed, Oct 20, 2021 at 10:53 AM Zhang, Chen <chen.zhang@intel.com>
> wrote:
> >
> >
> >
> > > -----Original Message-----
> > > From: Jason Wang <jasowang@redhat.com>
> > > Sent: Tuesday, October 19, 2021 3:39 PM
> > > To: Zhang, Chen <chen.zhang@intel.com>; Eric Blake
> > > <eblake@redhat.com>; Markus Armbruster <armbru@redhat.com>
> > > Cc: qemu-dev <qemu-devel@nongnu.org>; Li Zhijian
> > > <lizhijian@cn.fujitsu.com>; Lukas Straub <lukasstraub2@web.de>; Tao
> > > Xu <tao3.xu@intel.com>
> > > Subject: Re: [PATCH V3] net/colo: check vnet_hdr_support flag when
> > > using virtio-net
> > >
> > >
> > > 在 2021/9/18 上午10:04, Zhang Chen 写道:
> > > > When COLO use only one vnet_hdr_support parameter between COLO
> > > network
> > > > filter(filter-mirror, filter-redirector or filter-rewriter and
> > > > colo-compare, packet will not be parsed correctly. Acquire network
> > > > driver related to COLO, if it is nirtio-net,
> > >
> > >
> > > Typo.
> >
> > Oh~ will fix in next version.
> >
> > >
> > >
> > > >   check vnet_hdr_support flag of COLO network filter and colo-compare.
> > > >
> > > > Signed-off-by: Tao Xu <tao3.xu@intel.com>
> > > > Signed-off-by: Zhang Chen <chen.zhang@intel.com>
> > > > ---
> > > >
> > > > Changelog:
> > > > v3:
> > > >      Fix some typos.
> > > >      Rebased for Qemu 6.2.
> > > >
> > > > v2:
> > > >      Detect virtio-net driver and apply vnet_hdr_support
> > > >      automatically. (Jason)
> > > > ---
> > > >   net/colo-compare.c    | 57
> > > +++++++++++++++++++++++++++++++++++++++++++
> > > >   net/colo.c            | 20 +++++++++++++++
> > > >   net/colo.h            |  4 +++
> > > >   net/filter-mirror.c   | 21 ++++++++++++++++
> > > >   net/filter-rewriter.c | 10 ++++++++
> > > >   qapi/qom.json         |  6 +++++
> > > >   qemu-options.hx       |  6 +++--
> > > >   7 files changed, 122 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/net/colo-compare.c b/net/colo-compare.c index
> > > > b100e7b51f..870bd05a41 100644
> > > > --- a/net/colo-compare.c
> > > > +++ b/net/colo-compare.c
> > > > @@ -110,6 +110,7 @@ struct CompareState {
> > > >       char *sec_indev;
> > > >       char *outdev;
> > > >       char *notify_dev;
> > > > +    char *netdev;
> > > >       CharBackend chr_pri_in;
> > > >       CharBackend chr_sec_in;
> > > >       CharBackend chr_out;
> > > > @@ -838,6 +839,28 @@ static int compare_chr_can_read(void *opaque)
> > > >       return COMPARE_READ_LEN_MAX;
> > > >   }
> > > >
> > > > +static int colo_set_default_netdev(void *opaque, QemuOpts *opts,
> > > > +Error **errp) {
> > > > +    const char *colo_obj_type, *netdev_from_filter;
> > > > +    char **netdev = (char **)opaque;
> > > > +
> > > > +    colo_obj_type = qemu_opt_get(opts, "qom-type");
> > > > +
> > > > +    if (colo_obj_type &&
> > > > +        (strcmp(colo_obj_type, "filter-mirror") == 0 ||
> > > > +         strcmp(colo_obj_type, "filter-redirector") == 0 ||
> > > > +         strcmp(colo_obj_type, "filter-rewriter") == 0)) {
> > > > +        netdev_from_filter = qemu_opt_get(opts, "netdev");
> > > > +        if (*netdev == NULL) {
> > > > +            *netdev = g_strdup(netdev_from_filter);
> > > > +        } else if (strcmp(*netdev, netdev_from_filter) != 0) {
> > > > +            warn_report("%s is using a different netdev from other 
> > > > COLO "
> > > > +                        "component", colo_obj_type);
> > > > +        }
> > > > +    }
> > > > +    return 0;
> > > > +}
> > > > +
> > > >   /*
> > > >    * Called from the main thread on the primary for packets
> > > >    * arriving over the socket from the primary.
> > > > @@ -1050,6 +1073,21 @@ static void compare_set_vnet_hdr(Object
> *obj,
> > > >       s->vnet_hdr = value;
> > > >   }
> > > >
> > > > +static char *compare_get_netdev(Object *obj, Error **errp) {
> > > > +    CompareState *s = COLO_COMPARE(obj);
> > > > +
> > > > +    return g_strdup(s->netdev);
> > > > +}
> > > > +
> > > > +static void compare_set_netdev(Object *obj, const char *value,
> > > > +Error
> > > > +**errp) {
> > > > +    CompareState *s = COLO_COMPARE(obj);
> > > > +
> > > > +    g_free(s->netdev);
> > > > +    s->netdev = g_strdup(value);
> > > > +}
> > > > +
> > > >   static char *compare_get_notify_dev(Object *obj, Error **errp)
> > > >   {
> > > >       CompareState *s = COLO_COMPARE(obj); @@ -1274,6 +1312,12
> @@
> > > > static void colo_compare_complete(UserCreatable *uc, Error **errp)
> > > >           max_queue_size = MAX_QUEUE_SIZE;
> > > >       }
> > > >
> > > > +    if (!s->netdev) {
> > > > +        /* Set default netdev as the first colo netfilter found */
> > > > +        qemu_opts_foreach(qemu_find_opts("object"),
> > > > +                          colo_set_default_netdev, &s->netdev, NULL);
> > > > +    }
> > > > +
> > > >       if (find_and_check_chardev(&chr, s->pri_indev, errp) ||
> > > >           !qemu_chr_fe_init(&s->chr_pri_in, chr, errp)) {
> > > >           return;
> > > > @@ -1289,6 +1333,16 @@ static void
> > > colo_compare_complete(UserCreatable *uc, Error **errp)
> > > >           return;
> > > >       }
> > > >
> > > > +    if (!s->vnet_hdr &&
> > > > +        qemu_opts_foreach(qemu_find_opts("device"),
> > > > +                          vnet_driver_check, s->netdev, NULL)) {
> > > > +        /*
> > > > +         * colo compare needs 'vnet_hdr_support' when it works on
> virtio-net,
> > > > +         * add 'vnet_hdr_support' automatically
> > > > +         */
> > > > +        s->vnet_hdr = true;
> > > > +    }
> > > > +
> > > >       net_socket_rs_init(&s->pri_rs, compare_pri_rs_finalize, s-
> >vnet_hdr);
> > > >       net_socket_rs_init(&s->sec_rs, compare_sec_rs_finalize,
> > > > s->vnet_hdr);
> > > >
> > > > @@ -1400,6 +1454,9 @@ static void colo_compare_init(Object *obj)
> > > >       s->vnet_hdr = false;
> > > >       object_property_add_bool(obj, "vnet_hdr_support",
> > > compare_get_vnet_hdr,
> > > >                                compare_set_vnet_hdr);
> > > > +    /* colo compare can't varify that netdev is correct */
> > > > +    object_property_add_str(obj, "netdev", compare_get_netdev,
> > > > +                            compare_set_netdev);
> > > >   }
> > > >
> > > >   void colo_compare_cleanup(void)
> > > > diff --git a/net/colo.c b/net/colo.c index 3a3e6e89a0..4a03780f45
> > > > 100644
> > > > --- a/net/colo.c
> > > > +++ b/net/colo.c
> > > > @@ -243,3 +243,23 @@ bool connection_has_tracked(GHashTable
> > > > *connection_track_table,
> > > >
> > > >       return conn ? true : false;
> > > >   }
> > > > +
> > > > +/* check the network driver related to COLO, return 1 if it is
> > > > +virtio-net */ int vnet_driver_check(void *opaque, QemuOpts *opts,
> > > > +Error **errp) {
> > > > +    const char *driver_type, *netdev_from_driver;
> > > > +    char *netdev_from_filter = (char *)opaque;
> > > > +
> > > > +    driver_type = qemu_opt_get(opts, "driver");
> > > > +    netdev_from_driver = qemu_opt_get(opts, "netdev");
> > > > +
> > > > +    if (!driver_type || !netdev_from_driver || !netdev_from_filter) {
> > > > +        return 0;
> > > > +    }
> > > > +
> > > > +    if (g_str_has_prefix(driver_type, "virtio-net") &&
> > > > +        strcmp(netdev_from_driver, netdev_from_filter) == 0) {
> > > > +        return 1;
> > > > +    }
> > > > +    return 0;
> > > > +}
> > > > diff --git a/net/colo.h b/net/colo.h index d91cd245c4..d401fc76b6
> > > > 100644
> > > > --- a/net/colo.h
> > > > +++ b/net/colo.h
> > > > @@ -18,6 +18,9 @@
> > > >   #include "qemu/jhash.h"
> > > >   #include "qemu/timer.h"
> > > >   #include "net/eth.h"
> > > > +#include "qemu/option.h"
> > > > +#include "qemu/option_int.h"
> > > > +#include "qemu/config-file.h"
> > > >
> > > >   #define HASHTABLE_MAX_SIZE 16384
> > > >
> > > > @@ -104,5 +107,6 @@ Packet *packet_new(const void *data, int size,
> > > > int
> > > vnet_hdr_len);
> > > >   Packet *packet_new_nocopy(void *data, int size, int vnet_hdr_len);
> > > >   void packet_destroy(void *opaque, void *user_data);
> > > >   void packet_destroy_partial(void *opaque, void *user_data);
> > > > +int vnet_driver_check(void *opaque, QemuOpts *opts, Error
> > > > +**errp);
> > > >
> > > >   #endif /* NET_COLO_H */
> > > > diff --git a/net/filter-mirror.c b/net/filter-mirror.c index
> > > > f20240cc9f..69ca9c9839 100644
> > > > --- a/net/filter-mirror.c
> > > > +++ b/net/filter-mirror.c
> > > > @@ -12,6 +12,7 @@
> > > >   #include "qemu/osdep.h"
> > > >   #include "net/filter.h"
> > > >   #include "net/net.h"
> > > > +#include "net/colo.h"
> > > >   #include "qapi/error.h"
> > > >   #include "qom/object.h"
> > > >   #include "qemu/main-loop.h"
> > > > @@ -224,6 +225,16 @@ static void
> > > > filter_mirror_setup(NetFilterState *nf,
> > > Error **errp)
> > > >           return;
> > > >       }
> > > >
> > > > +    if (!s->vnet_hdr &&
> > > > +        qemu_opts_foreach(qemu_find_opts("device"),
> > > > +                          vnet_driver_check, nf->netdev_id, NULL)) {
> > > > +        /*
> > > > +         * filter mirror needs 'vnet_hdr_support' when colo filter 
> > > > modules
> > > > +         * work on virtio-net, add 'vnet_hdr_support' automatically
> > > > +         */
> > > > +        s->vnet_hdr = true;
> > > > +    }
> > > > +
> > > >       qemu_chr_fe_init(&s->chr_out, chr, errp);
> > > >   }
> > > >
> > > > @@ -252,6 +263,16 @@ static void
> > > > filter_redirector_setup(NetFilterState
> > > *nf, Error **errp)
> > > >           }
> > > >       }
> > > >
> > > > +    if (!s->vnet_hdr &&
> > > > +        qemu_opts_foreach(qemu_find_opts("device"),
> > > > +                          vnet_driver_check, nf->netdev_id, NULL)) {
> > > > +        /*
> > > > +         * filter redirector needs 'vnet_hdr_support' when colo filter
> modules
> > > > +         * work on virtio-net, add 'vnet_hdr_support' automatically
> > > > +         */
> > > > +        s->vnet_hdr = true;
> > > > +    }
> > > > +
> > > >       net_socket_rs_init(&s->rs, redirector_rs_finalize,
> > > > s->vnet_hdr);
> > > >
> > > >       if (s->indev) {
> > > > diff --git a/net/filter-rewriter.c b/net/filter-rewriter.c index
> > > > cb3a96cde1..637ef4ce71 100644
> > > > --- a/net/filter-rewriter.c
> > > > +++ b/net/filter-rewriter.c
> > > > @@ -388,6 +388,16 @@ static void
> > > > colo_rewriter_setup(NetFilterState *nf,
> > > Error **errp)
> > > >   {
> > > >       RewriterState *s = FILTER_REWRITER(nf);
> > > >
> > > > +    if (!s->vnet_hdr &&
> > > > +        qemu_opts_foreach(qemu_find_opts("device"),
> > > > +                          vnet_driver_check, nf->netdev_id, NULL)) {
> > > > +        /*
> > > > +         * filter rewriter needs 'vnet_hdr_support' when colo filter
> modules
> > > > +         * work on virtio-net, add 'vnet_hdr_support' automatically
> > > > +         */
> > > > +        s->vnet_hdr = true;
> > > > +    }
> > > > +
> > > >       s->connection_track_table =
> > > g_hash_table_new_full(connection_key_hash,
> > > >                                                         
> > > > connection_key_equal,
> > > >                                                         g_free,
> > > > diff --git a/qapi/qom.json b/qapi/qom.json index
> > > > a25616bc7a..5760107160
> > > > 100644
> > > > --- a/qapi/qom.json
> > > > +++ b/qapi/qom.json
> > > > @@ -241,6 +241,11 @@
> > > >   # @notify_dev: name of the character device backend to be used
> > > > to
> > > communicate
> > > >   #              with the remote colo-frame (only for Xen COLO)
> > > >   #
> > > > +# @netdev: id of the network device backend to colo-compare.
> Although
> > > > +#          colo-compare doesn't depend on network device directly, this
> > > > +#          parameter helps colo-compare know what network driver it is
> > > > +#          working on.(since 6.2)
> > >
> > >
> > > This looks kind of not elegant. We don't want to couple COLO with netdev.
> > >
> > > I wonder if we can do this without adding netdev.
> >
> > Yes, current COLO is not bind to netdev, but here we want to auto fix
> configuration issue.
> 
> If my memory is correct, the current design allows an external comparing
> module to work.

Yes, this netdev used by identify a series of comparing modules (include 
filters).

> 
> > To avoid wrong setting other non-colo related existing filter,  COLO need
> know the colo-effect netdev to setup.
> > And this parameter is optional, this patch will setup default colo-effect
> netdev in colo_set_default_netdev().
> > Or any good idea?
> 
> How about
> 
> 1) adding a handshake in the protocol before receiving packets or
> 2) add a header to the payload to show if it contains a vnet header or
> 3) go back to let mgmt set vnet_hdr=on/off (looks like the first proposal but
> it avoids the coupling).

Current code already have a header to the payload to show the vnet header(in 
net/filter-mirror.c filter_send()).
But the vnet_hdr_len is not necessary:
Disabled vnet_hdr payload:
1. size ---> 2. Real network payload.
Enbaled vnet_hdr payload:
1. size ---> 2. Vnet_hdr_len ----> 3. Real network payload.

It looks we can define the vnet_hdr_len as necessary part of protocol.
If no vnet_hdr, we set the vnet_hdr_len to 0.
1. size ---> 2. Vnet_hdr_len ----> 3. Real network payload.

How about this proposal?

Thanks
Chen


> 
> Thanks
> 
> >
> > Thanks
> > Chen
> >
> > >
> > > Thanks
> > >
> > >
> > > > +#
> > > >   # @compare_timeout: the maximum time to hold a packet from
> > > @primary_in for
> > > >   #                   comparison with an incoming packet on 
> > > > @secondary_in in
> > > >   #                   milliseconds (default: 3000)
> > > > @@ -264,6 +269,7 @@
> > > >               'outdev': 'str',
> > > >               'iothread': 'str',
> > > >               '*notify_dev': 'str',
> > > > +            '*netdev': 'str',
> > > >               '*compare_timeout': 'uint64',
> > > >               '*expired_scan_cycle': 'uint32',
> > > >               '*max_queue_size': 'uint32', diff --git
> > > > a/qemu-options.hx b/qemu-options.hx index 8f603cc7e6..250937fbbf
> > > > 100644
> > > > --- a/qemu-options.hx
> > > > +++ b/qemu-options.hx
> > > > @@ -4964,12 +4964,14 @@ SRST
> > > >           stored. The file format is libpcap, so it can be analyzed with
> > > >           tools such as tcpdump or Wireshark.
> > > >
> > > > -    ``-object colo-
> > >
> compare,id=id,primary_in=chardevid,secondary_in=chardevid,outdev=cha
> > > rd
> > > evid,iothread=id[,vnet_hdr_support][,notify_dev=id][,compare_timeout
> > > =@
> > >
> var{ms}][,expired_scan_cycle=@var{ms}][,max_queue_size=@var{size}]``
> > > > +    ``-object
> > > > + colo-
> > > compare,id=id,primary_in=chardevid,secondary_in=chardevid,outde
> > > > + v=chardevid,iothread=id[,netdev=netdevid][,vnet_hdr_support][,no
> > > > + tify
> > > > +
> > >
> _dev=id][,compare_timeout=@var{ms}][,expired_scan_cycle=@var{ms}][,
> > > m
> > > > + ax_queue_size=@var{size}]``
> > > >           Colo-compare gets packet from primary\_in chardevid and
> > > >           secondary\_in, then compare whether the payload of primary
> packet
> > > >           and secondary packet are the same. If same, it will output
> > > >           primary packet to out\_dev, else it will notify 
> > > > COLO-framework to
> do
> > > > -        checkpoint and send primary packet to out\_dev. In order to
> > > > +        checkpoint and send primary packet to out\_dev. Although
> > > > + colo-
> > > compare
> > > > +        does not depend on network device directly, netdevid helps
> > > > +        colo-compare know what network driver it is working on.
> > > > + In order to
> > > >           improve efficiency, we need to put the task of comparison in
> > > >           another iothread. If it has the vnet\_hdr\_support flag,
> > > >           colo compare will send/recv packet with vnet\_hdr\_len.
> >


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