Re: [PATCH v2] net/colo: check vnet_hdr_support flag when using virtio-net

[Lukas Straub]

On Thu, 26 Aug 2021 05:49:23 +0000
"Zhang, Chen" <chen.zhang@intel.com> wrote:

> > -----Original Message-----
> > From: Lukas Straub <lukasstraub2@web.de>
> > Sent: Sunday, August 22, 2021 12:25 AM
> > To: Xu, Tao3 <tao3.xu@intel.com>
> > Cc: Zhang, Chen <chen.zhang@intel.com>; lizhijian@cn.fujitsu.com;
> > jasowang@redhat.com; qemu-devel@nongnu.org
> > Subject: Re: [PATCH v2] net/colo: check vnet_hdr_support flag when using
> > virtio-net
> > 
> > On Thu, 19 Aug 2021 09:27:17 +0800
> > Tao Xu <tao3.xu@intel.com> wrote:
> >   
> > > 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, 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:
> > > 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;
> > > +}
> > > +  
> > 
> > Hi,
> > This doesn't properly handle the case where there are multiple network
> > devices and one is virtio-net and the other isn't. This would be a 
> > regression as
> > this worked fine before.  
> 
> No, If have multiple network device this patch just report a warning for it.
> You can still use virtio-net and others at the same time.

As you see it sets netdev to the first filter's netdev. So if
the first netdev is virtio-net and the 2nd is e1000 (for example) it'll
see virtio-net first and set *netdev to it for _both_ devices. Then it
sees the e1000 and prints the warning, but *netdev is still set to
virtio-net. So it'll enable vnet_hdr for e1000 too and segfault when
processing a packet because e1000 doesn't support vnet_hdr.

> >   
> > >  /*
> > >   * 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;
> > > +    }
> > > +  
> > 
> > There is no way to disable vnet_hdr_support with virtio-net now.  
> 
> Yes, It looks no reason to do this.
> Please show me some details?
> 
> Thanks
> Chen
> 
> >   
> > >      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 6d5f4a88e6..442a963ba4
> > > 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 help colo-compare know what network driver it is
> > > +#          working on
> > > +#
> > >  # @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 83aa59a920..b31ce3c87d 100644
> > > --- a/qemu-options.hx
> > > +++ b/qemu-options.hx
> > > @@ -4957,12 +4957,14 @@ 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=chard
> > 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][,notify
> > > +  
> > _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 help
> > > +        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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