RE: [ovs-dev] [PATCH net-next] openvswitch: add NSH support

[Yang, Yi Y]

struct ovs_action_encap_nsh is the only one way we transfer all the data for 
encap_nsh, netlink allows variable attribute, so I don't think we break netlink 
convention or abuse this variable feature.

Even if we bring nested attributes to handle this, OVS_ACTION_ATTR_ENCAP_NSH is 
still length-variable, OVS_NSH_ATTR_MD2 is also length-variable (it can be from 
0 to 248), so I don't think such way can avoid the issue you're addressing.

The result will be worse, it will make many difficulties when we transfer all 
the data for encap_nsh between OVS' components.

-Original Message-
From: Ben Pfaff [mailto:b...@ovn.org] 
Sent: Thursday, August 10, 2017 4:54 AM
To: Yang, Yi Y <yi.y.y...@intel.com>
Cc: Jan Scheurich <jan.scheur...@ericsson.com>; d...@openvswitch.org; 
netdev@vger.kernel.org; Jiri Benc <jb...@redhat.com>; da...@davemloft.net; 
Zoltán Balogh <zoltan.bal...@ericsson.com>
Subject: Re: [ovs-dev] [PATCH net-next] openvswitch: add NSH support

On Wed, Aug 09, 2017 at 08:12:36PM +, Yang, Yi Y wrote:
> Ben, do you mean we bring two new attributes (OVS_NSH_ATTR_MD1 and
> OVS_NSH_ATTR_MD2) and embed one of them in OVS_ACTION_ATTR_ENCAP_NSH?

Yes.

> Anyway we need to use a struct or something else to transfer those 
> metadata between functions, how do you think we can handle this 
> without metadata in struct ovs_action_encap_nsh? I mean how we handle 
> the arguments for function encap_nsh.

I guess that a pointer to the embedded nlattr with type OVS_NSH_ATTR_MD1 or 
OVS_NSH_ATTR2 should work OK.

Keep in mind that I'm not a kernel-side maintainer of any kind.  I am only 
passing along what I've perceived to be common Netlink protocol design patterns.

> -Original Message-
> From: netdev-ow...@vger.kernel.org 
> [mailto:netdev-ow...@vger.kernel.org] On Behalf Of Ben Pfaff
> Sent: Thursday, August 10, 2017 2:09 AM
> To: Yang, Yi Y <yi.y.y...@intel.com>
> Cc: Jan Scheurich <jan.scheur...@ericsson.com>; d...@openvswitch.org; 
> netdev@vger.kernel.org; Jiri Benc <jb...@redhat.com>; 
> da...@davemloft.net; Zoltán Balogh <zoltan.bal...@ericsson.com>
> Subject: Re: [ovs-dev] [PATCH net-next] openvswitch: add NSH support
> 
> On Wed, Aug 09, 2017 at 09:41:51AM +, Yang, Yi Y wrote:
> > Hi,  Jan
> > 
> > I have worked out a patch, will send it quickly for Ben. In 
> > addition, I also will send out a patch to change encap_nsh 
> > _nsh to push_nsh and pop_nsh. Per comments from all the 
> > people, we all agreed to do so :-)
> > 
> > diff --git a/datapath/linux/compat/include/linux/openvswitch.h
> > b/datapath/linux/compat/include/linux/openvswitch.h
> > index bc6c94b..4936c12 100644
> > --- a/datapath/linux/compat/include/linux/openvswitch.h
> > +++ b/datapath/linux/compat/include/linux/openvswitch.h
> > @@ -793,7 +793,7 @@ struct ovs_action_push_eth {
> > struct ovs_key_ethernet addresses;  };
> > 
> > -#define OVS_ENCAP_NSH_MAX_MD_LEN 16
> > +#define OVS_ENCAP_NSH_MAX_MD_LEN 248
> >  /*
> >   * struct ovs_action_encap_nsh - %OVS_ACTION_ATTR_ENCAP_NSH
> >   * @flags: NSH header flags.
> > @@ -809,7 +809,7 @@ struct ovs_action_encap_nsh {
> >  uint8_t mdlen;
> >  uint8_t np;
> >  __be32 path_hdr;
> > -uint8_t metadata[OVS_ENCAP_NSH_MAX_MD_LEN];
> > +uint8_t metadata[];
> >  };
> 
> This brings the overall format of ovs_action_encap_nsh to:
> 
> struct ovs_action_encap_nsh {
> uint8_t flags;
> uint8_t mdtype;
> uint8_t mdlen;
> uint8_t np;
> __be32 path_hdr;
> uint8_t metadata[];
> };
> 
> This is an unusual format for a Netlink attribute.  More commonly, one would 
> put variable-length data into an attribute of its own, which allows that data 
> to be handled using the regular Netlink means.  Then the mdlen and metadata 
> members could be removed, since they would be part of the additional 
> attribute, and one might expect the mdtype member to be removed as well since 
> each type of metadata would be in a different attribute type.
> 
> So, a format closer to what I expect to see in Netlink is something 
> like
> this:
> 
> /**
>  * enum ovs_nsh_attr - Metadata attributes for %OVS_ACTION_ENCAP_NSH action.
>  *
>  * @OVS_NSH_ATTR_MD1: Contains 16-byte NSH type-1 metadata.
>  * @OVS_NSH_ATTR_MD2: Contains 0- to 255-byte variable-length NSH 
> type-2
>  * metadata. */
> enum ovs_nsh_attr {
> OVS_NSH_ATTR_MD1,
> OVS_NSH_ATTR_MD2
> };
> 
> /*
>  * struct ovs_action_encap_nsh - %OVS_ACTION_ATTR_ENCAP_NSH
>  *
>  * @path_hdr: NSH service path id and service index.
>  * @flags: NSH header flags.
>  * @np: NSH next_protocol: Inner packet type.
>  *
>  * Followed by either %OVS_NSH_ATTR_MD1 or %OVS_NSH_ATTR_MD2 attribute.
>  */
> struct ovs_action_encap_nsh {
> __be32 path_hdr;
> uint8_t flags;
> uint8_t np;
> };

Re: [ovs-dev] [PATCH net-next] openvswitch: add NSH support

[Ben Pfaff]

On Wed, Aug 09, 2017 at 08:12:36PM +, Yang, Yi Y wrote:
> Ben, do you mean we bring two new attributes (OVS_NSH_ATTR_MD1 and
> OVS_NSH_ATTR_MD2) and embed one of them in OVS_ACTION_ATTR_ENCAP_NSH?

Yes.

> Anyway we need to use a struct or something else to transfer those
> metadata between functions, how do you think we can handle this
> without metadata in struct ovs_action_encap_nsh? I mean how we handle
> the arguments for function encap_nsh.

I guess that a pointer to the embedded nlattr with type OVS_NSH_ATTR_MD1
or OVS_NSH_ATTR2 should work OK.

Keep in mind that I'm not a kernel-side maintainer of any kind.  I am
only passing along what I've perceived to be common Netlink protocol
design patterns.

> -Original Message-
> From: netdev-ow...@vger.kernel.org [mailto:netdev-ow...@vger.kernel.org] On 
> Behalf Of Ben Pfaff
> Sent: Thursday, August 10, 2017 2:09 AM
> To: Yang, Yi Y <yi.y.y...@intel.com>
> Cc: Jan Scheurich <jan.scheur...@ericsson.com>; d...@openvswitch.org; 
> netdev@vger.kernel.org; Jiri Benc <jb...@redhat.com>; da...@davemloft.net; 
> Zoltán Balogh <zoltan.bal...@ericsson.com>
> Subject: Re: [ovs-dev] [PATCH net-next] openvswitch: add NSH support
> 
> On Wed, Aug 09, 2017 at 09:41:51AM +, Yang, Yi Y wrote:
> > Hi,  Jan
> > 
> > I have worked out a patch, will send it quickly for Ben. In addition, 
> > I also will send out a patch to change encap_nsh _nsh to 
> > push_nsh and pop_nsh. Per comments from all the people, we all agreed 
> > to do so :-)
> > 
> > diff --git a/datapath/linux/compat/include/linux/openvswitch.h 
> > b/datapath/linux/compat/include/linux/openvswitch.h
> > index bc6c94b..4936c12 100644
> > --- a/datapath/linux/compat/include/linux/openvswitch.h
> > +++ b/datapath/linux/compat/include/linux/openvswitch.h
> > @@ -793,7 +793,7 @@ struct ovs_action_push_eth {
> > struct ovs_key_ethernet addresses;  };
> > 
> > -#define OVS_ENCAP_NSH_MAX_MD_LEN 16
> > +#define OVS_ENCAP_NSH_MAX_MD_LEN 248
> >  /*
> >   * struct ovs_action_encap_nsh - %OVS_ACTION_ATTR_ENCAP_NSH
> >   * @flags: NSH header flags.
> > @@ -809,7 +809,7 @@ struct ovs_action_encap_nsh {
> >  uint8_t mdlen;
> >  uint8_t np;
> >  __be32 path_hdr;
> > -uint8_t metadata[OVS_ENCAP_NSH_MAX_MD_LEN];
> > +uint8_t metadata[];
> >  };
> 
> This brings the overall format of ovs_action_encap_nsh to:
> 
> struct ovs_action_encap_nsh {
> uint8_t flags;
> uint8_t mdtype;
> uint8_t mdlen;
> uint8_t np;
> __be32 path_hdr;
> uint8_t metadata[];
> };
> 
> This is an unusual format for a Netlink attribute.  More commonly, one would 
> put variable-length data into an attribute of its own, which allows that data 
> to be handled using the regular Netlink means.  Then the mdlen and metadata 
> members could be removed, since they would be part of the additional 
> attribute, and one might expect the mdtype member to be removed as well since 
> each type of metadata would be in a different attribute type.
> 
> So, a format closer to what I expect to see in Netlink is something like
> this:
> 
> /**
>  * enum ovs_nsh_attr - Metadata attributes for %OVS_ACTION_ENCAP_NSH action.
>  *
>  * @OVS_NSH_ATTR_MD1: Contains 16-byte NSH type-1 metadata.
>  * @OVS_NSH_ATTR_MD2: Contains 0- to 255-byte variable-length NSH type-2
>  * metadata. */
> enum ovs_nsh_attr {
> OVS_NSH_ATTR_MD1,
> OVS_NSH_ATTR_MD2
> };
> 
> /*
>  * struct ovs_action_encap_nsh - %OVS_ACTION_ATTR_ENCAP_NSH
>  *
>  * @path_hdr: NSH service path id and service index.
>  * @flags: NSH header flags.
>  * @np: NSH next_protocol: Inner packet type.
>  *
>  * Followed by either %OVS_NSH_ATTR_MD1 or %OVS_NSH_ATTR_MD2 attribute.
>  */
> struct ovs_action_encap_nsh {
> __be32 path_hdr;
> uint8_t flags;
> uint8_t np;
> };

RE: [ovs-dev] [PATCH net-next] openvswitch: add NSH support

[Yang, Yi Y]

Ben, do you mean we bring two new attributes (OVS_NSH_ATTR_MD1 and   
OVS_NSH_ATTR_MD2) and embed one of them in OVS_ACTION_ATTR_ENCAP_NSH? Anyway we 
need to use a struct or something else to transfer those metadata between 
functions, how do you think we can handle this without metadata in struct 
ovs_action_encap_nsh? I mean how we handle the arguments for function encap_nsh.

-Original Message-
From: netdev-ow...@vger.kernel.org [mailto:netdev-ow...@vger.kernel.org] On 
Behalf Of Ben Pfaff
Sent: Thursday, August 10, 2017 2:09 AM
To: Yang, Yi Y <yi.y.y...@intel.com>
Cc: Jan Scheurich <jan.scheur...@ericsson.com>; d...@openvswitch.org; 
netdev@vger.kernel.org; Jiri Benc <jb...@redhat.com>; da...@davemloft.net; 
Zoltán Balogh <zoltan.bal...@ericsson.com>
Subject: Re: [ovs-dev] [PATCH net-next] openvswitch: add NSH support

On Wed, Aug 09, 2017 at 09:41:51AM +, Yang, Yi Y wrote:
> Hi,  Jan
> 
> I have worked out a patch, will send it quickly for Ben. In addition, 
> I also will send out a patch to change encap_nsh _nsh to 
> push_nsh and pop_nsh. Per comments from all the people, we all agreed 
> to do so :-)
> 
> diff --git a/datapath/linux/compat/include/linux/openvswitch.h 
> b/datapath/linux/compat/include/linux/openvswitch.h
> index bc6c94b..4936c12 100644
> --- a/datapath/linux/compat/include/linux/openvswitch.h
> +++ b/datapath/linux/compat/include/linux/openvswitch.h
> @@ -793,7 +793,7 @@ struct ovs_action_push_eth {
> struct ovs_key_ethernet addresses;  };
> 
> -#define OVS_ENCAP_NSH_MAX_MD_LEN 16
> +#define OVS_ENCAP_NSH_MAX_MD_LEN 248
>  /*
>   * struct ovs_action_encap_nsh - %OVS_ACTION_ATTR_ENCAP_NSH
>   * @flags: NSH header flags.
> @@ -809,7 +809,7 @@ struct ovs_action_encap_nsh {
>  uint8_t mdlen;
>  uint8_t np;
>  __be32 path_hdr;
> -uint8_t metadata[OVS_ENCAP_NSH_MAX_MD_LEN];
> +uint8_t metadata[];
>  };

This brings the overall format of ovs_action_encap_nsh to:

struct ovs_action_encap_nsh {
uint8_t flags;
uint8_t mdtype;
uint8_t mdlen;
uint8_t np;
__be32 path_hdr;
uint8_t metadata[];
};

This is an unusual format for a Netlink attribute.  More commonly, one would 
put variable-length data into an attribute of its own, which allows that data 
to be handled using the regular Netlink means.  Then the mdlen and metadata 
members could be removed, since they would be part of the additional attribute, 
and one might expect the mdtype member to be removed as well since each type of 
metadata would be in a different attribute type.

So, a format closer to what I expect to see in Netlink is something like
this:

/**
 * enum ovs_nsh_attr - Metadata attributes for %OVS_ACTION_ENCAP_NSH action.
 *
 * @OVS_NSH_ATTR_MD1: Contains 16-byte NSH type-1 metadata.
 * @OVS_NSH_ATTR_MD2: Contains 0- to 255-byte variable-length NSH type-2
 * metadata. */
enum ovs_nsh_attr {
OVS_NSH_ATTR_MD1,
OVS_NSH_ATTR_MD2
};

/*
 * struct ovs_action_encap_nsh - %OVS_ACTION_ATTR_ENCAP_NSH
 *
 * @path_hdr: NSH service path id and service index.
 * @flags: NSH header flags.
 * @np: NSH next_protocol: Inner packet type.
 *
 * Followed by either %OVS_NSH_ATTR_MD1 or %OVS_NSH_ATTR_MD2 attribute.
 */
struct ovs_action_encap_nsh {
__be32 path_hdr;
uint8_t flags;
uint8_t np;
};

Re: [ovs-dev] [PATCH net-next] openvswitch: add NSH support

[Ben Pfaff]

On Wed, Aug 09, 2017 at 09:41:51AM +, Yang, Yi Y wrote:
> Hi,  Jan
> 
> I have worked out a patch, will send it quickly for Ben. In addition, I also 
> will send out a patch to change encap_nsh _nsh to push_nsh and pop_nsh. 
> Per comments from all the people, we all agreed to do so :-)
> 
> diff --git a/datapath/linux/compat/include/linux/openvswitch.h 
> b/datapath/linux/compat/include/linux/openvswitch.h
> index bc6c94b..4936c12 100644
> --- a/datapath/linux/compat/include/linux/openvswitch.h
> +++ b/datapath/linux/compat/include/linux/openvswitch.h
> @@ -793,7 +793,7 @@ struct ovs_action_push_eth {
> struct ovs_key_ethernet addresses;
>  };
> 
> -#define OVS_ENCAP_NSH_MAX_MD_LEN 16
> +#define OVS_ENCAP_NSH_MAX_MD_LEN 248
>  /*
>   * struct ovs_action_encap_nsh - %OVS_ACTION_ATTR_ENCAP_NSH
>   * @flags: NSH header flags.
> @@ -809,7 +809,7 @@ struct ovs_action_encap_nsh {
>  uint8_t mdlen;
>  uint8_t np;
>  __be32 path_hdr;
> -uint8_t metadata[OVS_ENCAP_NSH_MAX_MD_LEN];
> +uint8_t metadata[];
>  };

This brings the overall format of ovs_action_encap_nsh to:

struct ovs_action_encap_nsh {
uint8_t flags;
uint8_t mdtype;
uint8_t mdlen;
uint8_t np;
__be32 path_hdr;
uint8_t metadata[];
};

This is an unusual format for a Netlink attribute.  More commonly, one
would put variable-length data into an attribute of its own, which
allows that data to be handled using the regular Netlink means.  Then
the mdlen and metadata members could be removed, since they would be
part of the additional attribute, and one might expect the mdtype member
to be removed as well since each type of metadata would be in a
different attribute type.

So, a format closer to what I expect to see in Netlink is something like
this:

/**
 * enum ovs_nsh_attr - Metadata attributes for %OVS_ACTION_ENCAP_NSH action.
 *
 * @OVS_NSH_ATTR_MD1: Contains 16-byte NSH type-1 metadata.
 * @OVS_NSH_ATTR_MD2: Contains 0- to 255-byte variable-length NSH type-2
 * metadata. */
enum ovs_nsh_attr {
OVS_NSH_ATTR_MD1,
OVS_NSH_ATTR_MD2
};

/*
 * struct ovs_action_encap_nsh - %OVS_ACTION_ATTR_ENCAP_NSH
 *
 * @path_hdr: NSH service path id and service index.
 * @flags: NSH header flags.
 * @np: NSH next_protocol: Inner packet type.
 *
 * Followed by either %OVS_NSH_ATTR_MD1 or %OVS_NSH_ATTR_MD2 attribute.
 */
struct ovs_action_encap_nsh {
__be32 path_hdr;
uint8_t flags;
uint8_t np;
};

RE: [ovs-dev] [PATCH net-next] openvswitch: add NSH support

[Yang, Yi Y]

OVS_ENCAP_NSH_MAX_MD_LEN);
 ofpbuf_put_hex(, buf, );
-encap_nsh.mdlen = mdlen;
+encap_nsh->mdlen = mdlen;
 ofpbuf_uninit();
 }
 continue;
 }
 }
 out:
-if (ret < 0) {
-return ret;
-} else {
-size_t size = offsetof(struct ovs_action_encap_nsh, metadata)
-+ ROUND_UP(encap_nsh.mdlen, 4);
-nl_msg_put_unspec(actions, OVS_ACTION_ATTR_ENCAP_NSH,
-  _nsh, size);
-return n;
+if (ret >= 0) {
+size_t size = sizeof(struct ovs_action_encap_nsh)
+  + ROUND_UP(encap_nsh->mdlen, 4);
+size_t pad_len = size - sizeof(struct ovs_action_encap_nsh)
+ - encap_nsh->mdlen;
+if (encap_nsh->mdlen > NSH_M_TYPE1_MDLEN && pad_len > 0) {
+memset(encap_nsh->metadata + encap_nsh->mdlen, 0, pad_len);
+}
+nl_msg_put_unspec(actions, OVS_ACTION_ATTR_ENCAP_NSH, encap_nsh, size);
+ret = n;
 }
+free(encap_nsh);
+return ret;
 }

 static int
@@ -6798,19 +6803,22 @@ odp_put_encap_nsh_action(struct ofpbuf *odp_actions,
  const struct flow *flow,
  struct ofpbuf *encap_data)
 {
-struct ovs_action_encap_nsh encap_nsh;
-
-encap_nsh.flags = flow->nsh.flags;
-encap_nsh.mdtype = flow->nsh.mdtype;
-encap_nsh.np = flow->nsh.np;
-encap_nsh.path_hdr = htonl((ntohl(flow->nsh.spi) << NSH_SPI_SHIFT) |
+size_t size;
+size_t pad_len;
+struct ovs_action_encap_nsh *encap_nsh =
+xmalloc(sizeof *encap_nsh + OVS_ENCAP_NSH_MAX_MD_LEN);
+
+encap_nsh->flags = flow->nsh.flags;
+encap_nsh->mdtype = flow->nsh.mdtype;
+encap_nsh->np = flow->nsh.np;
+encap_nsh->path_hdr = htonl((ntohl(flow->nsh.spi) << NSH_SPI_SHIFT) |
flow->nsh.si);

-switch (encap_nsh.mdtype) {
+switch (encap_nsh->mdtype) {
 case NSH_M_TYPE1: {
 struct nsh_md1_ctx *md1 =
-ALIGNED_CAST(struct nsh_md1_ctx *, encap_nsh.metadata);
-encap_nsh.mdlen = NSH_M_TYPE1_MDLEN;
+ALIGNED_CAST(struct nsh_md1_ctx *, encap_nsh->metadata);
+encap_nsh->mdlen = NSH_M_TYPE1_MDLEN;
 for (int i = 0; i < 4; i++) {
 put_16aligned_be32(>c[i], flow->nsh.c[i]);
 }
@@ -6819,18 +6827,25 @@ odp_put_encap_nsh_action(struct ofpbuf *odp_actions,
 case NSH_M_TYPE2:
 if (encap_data) {
 ovs_assert(encap_data->size < OVS_ENCAP_NSH_MAX_MD_LEN);
-encap_nsh.mdlen = encap_data->size;
-memcpy(encap_nsh.metadata, encap_data->data, encap_data->size);
+encap_nsh->mdlen = encap_data->size;
+memcpy(encap_nsh->metadata, encap_data->data, encap_data->size);
 } else {
-encap_nsh.mdlen = 0;
+encap_nsh->mdlen = 0;
 }
 break;
 default:
-encap_nsh.mdlen = 0;
+encap_nsh->mdlen = 0;
 break;
 }
-nl_msg_put_unspec(odp_actions, OVS_ACTION_ATTR_ENCAP_NSH,
-  _nsh, sizeof(encap_nsh));
+size = sizeof(struct ovs_action_encap_nsh)
+   + ROUND_UP(encap_nsh->mdlen, 4);
+pad_len = size - sizeof(struct ovs_action_encap_nsh)
+  - encap_nsh->mdlen;
+if (pad_len > 0) {
+memset(encap_nsh->metadata + encap_nsh->mdlen, 0, pad_len);
+}
+nl_msg_put_unspec(odp_actions, OVS_ACTION_ATTR_ENCAP_NSH, encap_nsh, size);
+free(encap_nsh);
 }

 static void

-----Original Message-
From: Jan Scheurich [mailto:jan.scheur...@ericsson.com] 
Sent: Wednesday, August 9, 2017 4:32 PM
To: Ben Pfaff <b...@ovn.org>; Yang, Yi Y <yi.y.y...@intel.com>
Cc: d...@openvswitch.org; netdev@vger.kernel.org; Jiri Benc <jb...@redhat.com>; 
da...@davemloft.net; Zoltán Balogh <zoltan.bal...@ericsson.com>
Subject: RE: [ovs-dev] [PATCH net-next] openvswitch: add NSH support

Hi all,

In OVS 2.8 we support only fixed size NSH MD1 context data for matching and in 
set/copy_field actions. OVS parses an MD2 NSH header but does not make any TLV 
headers available to OF. The plan is to add support for matching/manipulating 
NSH MD2 TLVs through a new infrastructure of generic TLV match fields that can 
be dynamically mapped to specific protocol TLVs, similar to the way this is 
done for GENEVE tunnel metadata TLVs today. But this is work for an upcoming 
OVS release.

However, in encap() and decap() NSH actions we do support MD2 format already. 
The encap_nsh datapath action is agnostic of the MD format. Any MD2 TLV 
metadata are provided as encap properties in the OF encap() operation. They are 
translated by the ofproto layer and forwarded as opaque byte sequence in the 
encap

RE: [ovs-dev] [PATCH net-next] openvswitch: add NSH support

[Jan Scheurich]

Hi all,

In OVS 2.8 we support only fixed size NSH MD1 context data for matching and in 
set/copy_field actions. OVS parses an MD2 NSH header but does not make any TLV 
headers available to OF. The plan is to add support for matching/manipulating 
NSH MD2 TLVs through a new infrastructure of generic TLV match fields that can 
be dynamically mapped to specific protocol TLVs, similar to the way this is 
done for GENEVE tunnel metadata TLVs today. But this is work for an upcoming 
OVS release.

However, in encap() and decap() NSH actions we do support MD2 format already. 
The encap_nsh datapath action is agnostic of the MD format. Any MD2 TLV 
metadata are provided as encap properties in the OF encap() operation. They are 
translated by the ofproto layer and forwarded as opaque byte sequence in the 
encap_nsh datapath action.

Conversely, the decap_nsh() action pops any TLV metadata using the metadata 
length in the NSH header.

Consequently the datapath action OVS_ACTION_ATTR_ENCAP_NSH is already declared 
variable length:

odp_action_len(uint16_t type)
{
switch ((enum ovs_action_attr) type) {
...
case OVS_ACTION_ATTR_ENCAP_NSH: return ATTR_LEN_VARIABLE;
case OVS_ACTION_ATTR_DECAP_NSH: return 0;
...
}

Unfortunately, that has only partially been reflected in the rest of the code. 
The action struct should have a variable length metadata[] member and the 
function odp_put_encap_nsh_action() should set the action nl_attr length 
dynamically.

I'll provide a patch to fix that shortly.

BTW: I have no objections to renaming these datapath actions to push_nsh and 
pop_nsh if that helps avoiding confusion with the existing encap attributes on 
the netlink interface. But we should do that quickly as it is user-visible and 
affects unit test cases.

BR, Jan


> -Original Message-
> From: ovs-dev-boun...@openvswitch.org 
> [mailto:ovs-dev-boun...@openvswitch.org] On Behalf Of Ben Pfaff
> Sent: Wednesday, 09 August, 2017 04:42
> To: Yang, Yi Y <yi.y.y...@intel.com>
> Cc: d...@openvswitch.org; netdev@vger.kernel.org; Jiri Benc 
> <jb...@redhat.com>; da...@davemloft.net
> Subject: Re: [ovs-dev] [PATCH net-next] openvswitch: add NSH support
> 
> To be clear, the OVS implementation is a placeholder.  It will get
> replaced by whatever netdev implements, and that's OK.  I didn't focus
> on making it perfect because I knew that.  Instead, I just made sure it
> was good enough for an internal OVS implementation that doesn't fix any
> ABI or API.  OVS can even change the user-visible action names, as long
> as we do that soon (and encap/decap versus push/pop doesn't matter to
> me).
> 
> The considerations for netdev are different and more permanent.
> 
> On Wed, Aug 09, 2017 at 02:05:12AM +, Yang, Yi Y wrote:
> > Hi, Jiri
> >
> > Thank you for your comments.
> >
> > __be32 c[4] is the name Ben Pfaff suggested, the original name is c1, c2, 
> > c3, c4, they are context data, so c seems ok, too :-)
> >
> > OVS has merged it and has the same name, maybe the better way is adding 
> > comment /* Context data */ after it.
> >
> > For MD type 2, struct ovs_key_nsh is very difficult to cover it, so far we 
> > don't know how to support MD type 2 better, Geneve defined 64
> tun_metadata0-63 to handle this, those keys are parts of struct flow_tnl, the 
> highest possibility is to reuse those keys.
> >
> > So for future MD type 2, we will have two parts of keys, one is from struct 
> > ovs_key_nsh, another is from struct flow_tnl, this won't break
> the old uAPI.
> >
> > "#define OVS_ENCAP_NSH_MAX_MD_LEN 16" is changed per Ben's comment from 
> > 256, Ben thinks 256 is too big but we only support
> MD type 1 now. We still have ways to extend it, for example:
> >
> > struct ovs_action_encap_nsh * oaen = (struct ovs_action_encap_nsh *) malloc 
> > (sizeof(struct ovs_action_encap_nsh) + ANY_SIZE);
> >
> > nl_msg_put_unspec(actions, OVS_ACTION_ATTR_ENCAP_NSH,
> >   oaen, sizeof(struct ovs_action_encap_nsh) + 
> > ANY_SIZE);
> >
> > In addition, we also need to consider, OVS userspace code must be 
> > consistent with here, so keeping it intact will be better, we have way
> to support dynamically extension when we add MD type 2 support.
> >
> > About action name, unfortunately, userspace data plane has named them as 
> > encap_nsh & decap_nsh, Jan, what do you think about Jiri's
> suggestion?
> >
> > But from my understanding, encap_* & decap_* are better because they 
> > corresponding to generic encap & decap actions, in addition,
> encap semantics are different from push, encap just pushed an empty header 
> with default values, users must use set_field to set the
> co

Re: [ovs-dev] [PATCH net-next] openvswitch: add NSH support

[Ben Pfaff]

To be clear, the OVS implementation is a placeholder.  It will get
replaced by whatever netdev implements, and that's OK.  I didn't focus
on making it perfect because I knew that.  Instead, I just made sure it
was good enough for an internal OVS implementation that doesn't fix any
ABI or API.  OVS can even change the user-visible action names, as long
as we do that soon (and encap/decap versus push/pop doesn't matter to
me).

The considerations for netdev are different and more permanent.

On Wed, Aug 09, 2017 at 02:05:12AM +, Yang, Yi Y wrote:
> Hi, Jiri
> 
> Thank you for your comments.
> 
> __be32 c[4] is the name Ben Pfaff suggested, the original name is c1, c2, c3, 
> c4, they are context data, so c seems ok, too :-)
> 
> OVS has merged it and has the same name, maybe the better way is adding 
> comment /* Context data */ after it.
> 
> For MD type 2, struct ovs_key_nsh is very difficult to cover it, so far we 
> don't know how to support MD type 2 better, Geneve defined 64 
> tun_metadata0-63 to handle this, those keys are parts of struct flow_tnl, the 
> highest possibility is to reuse those keys.
> 
> So for future MD type 2, we will have two parts of keys, one is from struct 
> ovs_key_nsh, another is from struct flow_tnl, this won't break the old uAPI.
> 
> "#define OVS_ENCAP_NSH_MAX_MD_LEN 16" is changed per Ben's comment from 256, 
> Ben thinks 256 is too big but we only support MD type 1 now. We still have 
> ways to extend it, for example:
> 
> struct ovs_action_encap_nsh * oaen = (struct ovs_action_encap_nsh *) malloc 
> (sizeof(struct ovs_action_encap_nsh) + ANY_SIZE);
> 
> nl_msg_put_unspec(actions, OVS_ACTION_ATTR_ENCAP_NSH,
>   oaen, sizeof(struct ovs_action_encap_nsh) + 
> ANY_SIZE);
> 
> In addition, we also need to consider, OVS userspace code must be consistent 
> with here, so keeping it intact will be better, we have way to support 
> dynamically extension when we add MD type 2 support.
> 
> About action name, unfortunately, userspace data plane has named them as 
> encap_nsh & decap_nsh, Jan, what do you think about Jiri's suggestion?
> 
> But from my understanding, encap_* & decap_* are better because they 
> corresponding to generic encap & decap actions, in addition, encap semantics 
> are different from push, encap just pushed an empty header with default 
> values, users must use set_field to set the content of the header.
> 
> Again, OVS userspace code must be consistent with here, so keeping it intact 
> will be better because OVS userspace code was there.
> 
> 
> -Original Message-
> From: netdev-ow...@vger.kernel.org [mailto:netdev-ow...@vger.kernel.org] On 
> Behalf Of Jiri Benc
> Sent: Tuesday, August 8, 2017 10:28 PM
> To: Yang, Yi Y 
> Cc: netdev@vger.kernel.org; d...@openvswitch.org; da...@davemloft.net
> Subject: Re: [PATCH net-next] openvswitch: add NSH support
> 
> On Tue,  8 Aug 2017 12:59:40 +0800, Yi Yang wrote:
> > +struct ovs_key_nsh {
> > +   __u8 flags;
> > +   __u8 mdtype;
> > +   __u8 np;
> > +   __u8 pad;
> > +   __be32 path_hdr;
> > +   __be32 c[4];
> 
> "c" is a very poor name. Please rename it to something that expresses what 
> this field contains.
> 
> Also, this looks like MD type 1 only. How are those fields going to work with 
> MD type 2? I don't think MD type 2 implementation is necessary in this patch 
> but I'd like to know how this is going to work - it's uAPI and thus set in 
> stone once this is merged. The uAPI needs to be designed with future use in 
> mind.
> 
> > +#define OVS_ENCAP_NSH_MAX_MD_LEN 16
> > +/*
> > + * struct ovs_action_encap_nsh - %OVS_ACTION_ATTR_ENCAP_NSH
> > + * @flags: NSH header flags.
> > + * @mdtype: NSH metadata type.
> > + * @mdlen: Length of NSH metadata in bytes.
> > + * @np: NSH next_protocol: Inner packet type.
> > + * @path_hdr: NSH service path id and service index.
> > + * @metadata: NSH metadata for MD type 1 or 2  */ struct 
> > +ovs_action_encap_nsh {
> > +   __u8 flags;
> > +   __u8 mdtype;
> > +   __u8 mdlen;
> > +   __u8 np;
> > +   __be32 path_hdr;
> > +   __u8 metadata[OVS_ENCAP_NSH_MAX_MD_LEN];
> 
> This is wrong. The metadata size is set to a fixed size by this and cannot be 
> ever extended, or at least not easily. Netlink has attributes for exactly 
> these cases and that's what needs to be used here.
> 
> > @@ -835,6 +866,8 @@ enum ovs_action_attr {
> > OVS_ACTION_ATTR_TRUNC,/* u32 struct ovs_action_trunc. */
> > OVS_ACTION_ATTR_PUSH_ETH, /* struct ovs_action_push_eth. */
> > OVS_ACTION_ATTR_POP_ETH,  /* No argument. */
> > +   OVS_ACTION_ATTR_ENCAP_NSH,/* struct ovs_action_encap_nsh. */
> > +   OVS_ACTION_ATTR_DECAP_NSH,/* No argument. */
> 
> Use "push" and "pop", not "encap" and "decap" to be consistent with the 
> naming in the rest of the file. We use encap and decap for tunnel operations. 
> This code does not use lwtunnels, thus push and pop is more appropriate.
> 
>  Jiri
>