Re: [ovs-dev] [PATCH net-next] net: openvswitch: add hash info to upcall

[Tonghao Zhang]

> On Nov 12, 2019, at 12:35 PM, Pravin Shelar  wrote:
> 
>> On Sun, Nov 10, 2019 at 3:44 AM  wrote:
>> 
>> From: Tonghao Zhang 
>> 
>> When using the kernel datapath, the upcall don't
>> add skb hash info relatived. That will introduce
>> some problem, because the hash of skb is very
>> important (e.g. vxlan module uses it for udp src port,
>> tx queue selection on tx path.).
>> 
>> For example, there will be one upcall, without information
>> skb hash, to ovs-vswitchd, for the first packet of one tcp
>> session. When kernel sents the tcp packets, the hash is
>> random for a tcp socket:
>> 
>> tcp_v4_connect
>>  -> sk_set_txhash (is random)
>> 
>> __tcp_transmit_skb
>>  -> skb_set_hash_from_sk
>> 
>> Then the udp src port of first tcp packet is different
>> from rest packets. The topo is shown.
>> 
>> $ ovs-vsctl add-br br-int
>> $ ovs-vsctl add-port br-int vxl0 -- \
>>set Interface vxl0 type=vxlan options:key=100 
>> options:remote_ip=1.1.1.200
>> 
>> $ __tap is internal type on host
>> $ or tap net device for VM/Dockers
>> $ ovs-vsctl add-port br-int __tap
>> 
>> +---+  +-+
>> |   Docker/VMs  |  | ovs-vswitchd|
>> ++--+  +-+
>> |   ^|
>> |   ||
>> |   |  upcallv recalculate packet hash
>> | +-++--+
>> |  tap netdev | |   vxlan modules
>> +---> +-->  Open vSwitch ko   --+--->
>>   internal type   | |
>>   +-+
>> 
>> Reported-at: 
>> https://mail.openvswitch.org/pipermail/ovs-dev/2019-October/364062.html
>> Signed-off-by: Tonghao Zhang 
>> ---
>> include/uapi/linux/openvswitch.h |  2 ++
>> net/openvswitch/datapath.c   | 31 ++-
>> net/openvswitch/datapath.h   |  3 +++
>> 3 files changed, 35 insertions(+), 1 deletion(-)
>> 
>> diff --git a/include/uapi/linux/openvswitch.h 
>> b/include/uapi/linux/openvswitch.h
>> index 1887a451c388..1c58e019438e 100644
>> --- a/include/uapi/linux/openvswitch.h
>> +++ b/include/uapi/linux/openvswitch.h
>> @@ -170,6 +170,7 @@ enum ovs_packet_cmd {
>>  * output port is actually a tunnel port. Contains the output tunnel key
>>  * extracted from the packet as nested %OVS_TUNNEL_KEY_ATTR_* attributes.
>>  * @OVS_PACKET_ATTR_MRU: Present for an %OVS_PACKET_CMD_ACTION and
>> + * @OVS_PACKET_ATTR_HASH: Packet hash info (e.g. hash, sw_hash and l4_hash 
>> in skb)
>>  * @OVS_PACKET_ATTR_LEN: Packet size before truncation.
>>  * %OVS_PACKET_ATTR_USERSPACE action specify the Maximum received fragment
>>  * size.
>> @@ -190,6 +191,7 @@ enum ovs_packet_attr {
>>OVS_PACKET_ATTR_PROBE,  /* Packet operation is a feature probe,
>>   error logging should be suppressed. */
>>OVS_PACKET_ATTR_MRU,/* Maximum received IP fragment size. */
>> +   OVS_PACKET_ATTR_HASH,   /* Packet hash. */
>>OVS_PACKET_ATTR_LEN,/* Packet size before truncation. */
>>__OVS_PACKET_ATTR_MAX
>> };
>> diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
>> index 2088619c03f0..f938c43e3085 100644
>> --- a/net/openvswitch/datapath.c
>> +++ b/net/openvswitch/datapath.c
>> @@ -350,7 +350,8 @@ static size_t upcall_msg_size(const struct 
>> dp_upcall_info *upcall_info,
>>size_t size = NLMSG_ALIGN(sizeof(struct ovs_header))
>>+ nla_total_size(hdrlen) /* OVS_PACKET_ATTR_PACKET */
>>+ nla_total_size(ovs_key_attr_size()) /* OVS_PACKET_ATTR_KEY 
>> */
>> -   + nla_total_size(sizeof(unsigned int)); /* 
>> OVS_PACKET_ATTR_LEN */
>> +   + nla_total_size(sizeof(unsigned int)) /* 
>> OVS_PACKET_ATTR_LEN */
>> +   + nla_total_size(sizeof(u64)); /* OVS_PACKET_ATTR_HASH */
>> 
>>/* OVS_PACKET_ATTR_USERDATA */
>>if (upcall_info->userdata)
>> @@ -393,6 +394,7 @@ static int queue_userspace_packet(struct datapath *dp, 
>> struct sk_buff *skb,
>>size_t len;
>>unsigned int hlen;
>>int err, dp_ifindex;
>> +   u64 hash;
>> 
>>dp_ifindex = get_dpifindex(dp);
>>if (!dp_ifindex)
>> @@ -504,6 +506,24 @@ static int queue_userspace_packet(struct datapath *dp, 
>> struct sk_buff *skb,
>>pad_packet(dp, user_skb);
>>}
>> 
>> +   if (skb_get_hash_raw(skb)) {
> skb_get_hash_raw() never fails to return hash, so I do not see point
> of checking hash value.
If hash value is 0, we don't add hash info to upcall.
> 
>> +   hash = skb_get_hash_raw(skb);
>> +
>> +   if (skb->sw_hash)
>> +   hash |= OVS_PACKET_HASH_SW;
>> +
>> +   if (skb->l4_hash)
>> +   hash 

Re: [ovs-dev] [PATCH net-next] net: openvswitch: add hash info to upcall

[Pravin Shelar]

On Sun, Nov 10, 2019 at 3:44 AM  wrote:
>
> From: Tonghao Zhang 
>
> When using the kernel datapath, the upcall don't
> add skb hash info relatived. That will introduce
> some problem, because the hash of skb is very
> important (e.g. vxlan module uses it for udp src port,
> tx queue selection on tx path.).
>
> For example, there will be one upcall, without information
> skb hash, to ovs-vswitchd, for the first packet of one tcp
> session. When kernel sents the tcp packets, the hash is
> random for a tcp socket:
>
> tcp_v4_connect
>   -> sk_set_txhash (is random)
>
> __tcp_transmit_skb
>   -> skb_set_hash_from_sk
>
> Then the udp src port of first tcp packet is different
> from rest packets. The topo is shown.
>
> $ ovs-vsctl add-br br-int
> $ ovs-vsctl add-port br-int vxl0 -- \
> set Interface vxl0 type=vxlan options:key=100 
> options:remote_ip=1.1.1.200
>
> $ __tap is internal type on host
> $ or tap net device for VM/Dockers
> $ ovs-vsctl add-port br-int __tap
>
> +---+  +-+
> |   Docker/VMs  |  | ovs-vswitchd|
> ++--+  +-+
>  |   ^|
>  |   ||
>  |   |  upcallv recalculate packet hash
>  | +-++--+
>  |  tap netdev | |   vxlan modules
>  +---> +-->  Open vSwitch ko   --+--->
>internal type   | |
>+-+
>
> Reported-at: 
> https://mail.openvswitch.org/pipermail/ovs-dev/2019-October/364062.html
> Signed-off-by: Tonghao Zhang 
> ---
>  include/uapi/linux/openvswitch.h |  2 ++
>  net/openvswitch/datapath.c   | 31 ++-
>  net/openvswitch/datapath.h   |  3 +++
>  3 files changed, 35 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/openvswitch.h 
> b/include/uapi/linux/openvswitch.h
> index 1887a451c388..1c58e019438e 100644
> --- a/include/uapi/linux/openvswitch.h
> +++ b/include/uapi/linux/openvswitch.h
> @@ -170,6 +170,7 @@ enum ovs_packet_cmd {
>   * output port is actually a tunnel port. Contains the output tunnel key
>   * extracted from the packet as nested %OVS_TUNNEL_KEY_ATTR_* attributes.
>   * @OVS_PACKET_ATTR_MRU: Present for an %OVS_PACKET_CMD_ACTION and
> + * @OVS_PACKET_ATTR_HASH: Packet hash info (e.g. hash, sw_hash and l4_hash 
> in skb)
>   * @OVS_PACKET_ATTR_LEN: Packet size before truncation.
>   * %OVS_PACKET_ATTR_USERSPACE action specify the Maximum received fragment
>   * size.
> @@ -190,6 +191,7 @@ enum ovs_packet_attr {
> OVS_PACKET_ATTR_PROBE,  /* Packet operation is a feature probe,
>error logging should be suppressed. */
> OVS_PACKET_ATTR_MRU,/* Maximum received IP fragment size. */
> +   OVS_PACKET_ATTR_HASH,   /* Packet hash. */
> OVS_PACKET_ATTR_LEN,/* Packet size before truncation. */
> __OVS_PACKET_ATTR_MAX
>  };
> diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
> index 2088619c03f0..f938c43e3085 100644
> --- a/net/openvswitch/datapath.c
> +++ b/net/openvswitch/datapath.c
> @@ -350,7 +350,8 @@ static size_t upcall_msg_size(const struct dp_upcall_info 
> *upcall_info,
> size_t size = NLMSG_ALIGN(sizeof(struct ovs_header))
> + nla_total_size(hdrlen) /* OVS_PACKET_ATTR_PACKET */
> + nla_total_size(ovs_key_attr_size()) /* OVS_PACKET_ATTR_KEY 
> */
> -   + nla_total_size(sizeof(unsigned int)); /* 
> OVS_PACKET_ATTR_LEN */
> +   + nla_total_size(sizeof(unsigned int)) /* OVS_PACKET_ATTR_LEN 
> */
> +   + nla_total_size(sizeof(u64)); /* OVS_PACKET_ATTR_HASH */
>
> /* OVS_PACKET_ATTR_USERDATA */
> if (upcall_info->userdata)
> @@ -393,6 +394,7 @@ static int queue_userspace_packet(struct datapath *dp, 
> struct sk_buff *skb,
> size_t len;
> unsigned int hlen;
> int err, dp_ifindex;
> +   u64 hash;
>
> dp_ifindex = get_dpifindex(dp);
> if (!dp_ifindex)
> @@ -504,6 +506,24 @@ static int queue_userspace_packet(struct datapath *dp, 
> struct sk_buff *skb,
> pad_packet(dp, user_skb);
> }
>
> +   if (skb_get_hash_raw(skb)) {
skb_get_hash_raw() never fails to return hash, so I do not see point
of checking hash value.

> +   hash = skb_get_hash_raw(skb);
> +
> +   if (skb->sw_hash)
> +   hash |= OVS_PACKET_HASH_SW;
> +
> +   if (skb->l4_hash)
> +   hash |= OVS_PACKET_HASH_L4;
> +
> +   if (nla_put(user_skb, OVS_PACKET_ATTR_HASH,
> +   sizeof (u64), )) {
> +   err = -ENOBUFS;
> +   goto 

Re: [ovs-dev] [PATCH net-next] net: openvswitch: add hash info to upcall

[Tonghao Zhang]

On Mon, Nov 11, 2019 at 9:07 PM Simon Horman  wrote:
>
> On Sun, Nov 10, 2019 at 07:44:18PM +0800, xiangxia.m@gmail.com wrote:
> > From: Tonghao Zhang 
> >
> > When using the kernel datapath, the upcall don't
> > add skb hash info relatived. That will introduce
> > some problem, because the hash of skb is very
> > important (e.g. vxlan module uses it for udp src port,
> > tx queue selection on tx path.).
> >
> > For example, there will be one upcall, without information
> > skb hash, to ovs-vswitchd, for the first packet of one tcp
> > session. When kernel sents the tcp packets, the hash is
> > random for a tcp socket:
> >
> > tcp_v4_connect
> >   -> sk_set_txhash (is random)
> >
> > __tcp_transmit_skb
> >   -> skb_set_hash_from_sk
> >
> > Then the udp src port of first tcp packet is different
> > from rest packets. The topo is shown.
> >
> > $ ovs-vsctl add-br br-int
> > $ ovs-vsctl add-port br-int vxl0 -- \
> >   set Interface vxl0 type=vxlan options:key=100 
> > options:remote_ip=1.1.1.200
> >
> > $ __tap is internal type on host
> > $ or tap net device for VM/Dockers
> > $ ovs-vsctl add-port br-int __tap
> >
> > +---+  +-+
> > |   Docker/VMs  |  | ovs-vswitchd|
> > ++--+  +-+
> >  |   ^|
> >  |   ||
> >  |   |  upcallv recalculate packet hash
> >  | +-++--+
> >  |  tap netdev | |   vxlan modules
> >  +---> +-->  Open vSwitch ko   --+--->
> >internal type   | |
> >+-+
>
> I think I see the problem that you are trying to solve, but this approach
> feels wrong to me. In my view the HASH is transparent to components
> outside of the datapath (in this case the Open vSwitch ko box).
The hash affects the vxlan modules to select the udp src port and tx
queue selection.

> For one thing, with this change ovs-vswitchd can now supply any hash
> value it likes.
the patch for ovs-vswitchd is not sent for now, this patch will get
the hash from upcall
and sent it back to kernel.
> Is it not possible to fix things so that "recalculate packet hash"
> in fact recalculates the same hash value as was calculated before
> the upcall?
Hi, Simon
I don't get a better solution, because the hash calculated with
different way, for example
hash is random for tcp which may come from host or VMs, and hash may
is calculated in hw, software.

> >
> > Reported-at: 
> > https://mail.openvswitch.org/pipermail/ovs-dev/2019-October/364062.html
> > Signed-off-by: Tonghao Zhang 
> > ---
> >  include/uapi/linux/openvswitch.h |  2 ++
> >  net/openvswitch/datapath.c   | 31 ++-
> >  net/openvswitch/datapath.h   |  3 +++
> >  3 files changed, 35 insertions(+), 1 deletion(-)
> >
> > diff --git a/include/uapi/linux/openvswitch.h 
> > b/include/uapi/linux/openvswitch.h
> > index 1887a451c388..1c58e019438e 100644
> > --- a/include/uapi/linux/openvswitch.h
> > +++ b/include/uapi/linux/openvswitch.h
> > @@ -170,6 +170,7 @@ enum ovs_packet_cmd {
> >   * output port is actually a tunnel port. Contains the output tunnel key
> >   * extracted from the packet as nested %OVS_TUNNEL_KEY_ATTR_* attributes.
> >   * @OVS_PACKET_ATTR_MRU: Present for an %OVS_PACKET_CMD_ACTION and
> > + * @OVS_PACKET_ATTR_HASH: Packet hash info (e.g. hash, sw_hash and l4_hash 
> > in skb)
> >   * @OVS_PACKET_ATTR_LEN: Packet size before truncation.
> >   * %OVS_PACKET_ATTR_USERSPACE action specify the Maximum received fragment
> >   * size.
> > @@ -190,6 +191,7 @@ enum ovs_packet_attr {
> >   OVS_PACKET_ATTR_PROBE,  /* Packet operation is a feature probe,
> >  error logging should be suppressed. */
> >   OVS_PACKET_ATTR_MRU,/* Maximum received IP fragment size. */
> > + OVS_PACKET_ATTR_HASH,   /* Packet hash. */
> >   OVS_PACKET_ATTR_LEN,/* Packet size before truncation. */
> >   __OVS_PACKET_ATTR_MAX
> >  };
> > diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
> > index 2088619c03f0..f938c43e3085 100644
> > --- a/net/openvswitch/datapath.c
> > +++ b/net/openvswitch/datapath.c
> > @@ -350,7 +350,8 @@ static size_t upcall_msg_size(const struct 
> > dp_upcall_info *upcall_info,
> >   size_t size = NLMSG_ALIGN(sizeof(struct ovs_header))
> >   + nla_total_size(hdrlen) /* OVS_PACKET_ATTR_PACKET */
> >   + nla_total_size(ovs_key_attr_size()) /* OVS_PACKET_ATTR_KEY 
> > */
> > - + nla_total_size(sizeof(unsigned int)); /* 
> > OVS_PACKET_ATTR_LEN */
> > + + nla_total_size(sizeof(unsigned int)) /* OVS_PACKET_ATTR_LEN 
> > */
> > + + nla_total_size(sizeof(u64)); 

Re: [ovs-dev] [PATCH net-next] net: openvswitch: add hash info to upcall

[Simon Horman]

On Sun, Nov 10, 2019 at 07:44:18PM +0800, xiangxia.m@gmail.com wrote:
> From: Tonghao Zhang 
> 
> When using the kernel datapath, the upcall don't
> add skb hash info relatived. That will introduce
> some problem, because the hash of skb is very
> important (e.g. vxlan module uses it for udp src port,
> tx queue selection on tx path.).
> 
> For example, there will be one upcall, without information
> skb hash, to ovs-vswitchd, for the first packet of one tcp
> session. When kernel sents the tcp packets, the hash is
> random for a tcp socket:
> 
> tcp_v4_connect
>   -> sk_set_txhash (is random)
> 
> __tcp_transmit_skb
>   -> skb_set_hash_from_sk
> 
> Then the udp src port of first tcp packet is different
> from rest packets. The topo is shown.
> 
> $ ovs-vsctl add-br br-int
> $ ovs-vsctl add-port br-int vxl0 -- \
>   set Interface vxl0 type=vxlan options:key=100 
> options:remote_ip=1.1.1.200
> 
> $ __tap is internal type on host
> $ or tap net device for VM/Dockers
> $ ovs-vsctl add-port br-int __tap
> 
> +---+  +-+
> |   Docker/VMs  |  | ovs-vswitchd|
> ++--+  +-+
>  |   ^|
>  |   ||
>  |   |  upcallv recalculate packet hash
>  | +-++--+
>  |  tap netdev | |   vxlan modules
>  +---> +-->  Open vSwitch ko   --+--->
>internal type   | |
>+-+

I think I see the problem that you are trying to solve, but this approach
feels wrong to me. In my view the HASH is transparent to components
outside of the datapath (in this case the Open vSwitch ko box).

For one thing, with this change ovs-vswitchd can now supply any hash
value it likes.

Is it not possible to fix things so that "recalculate packet hash"
in fact recalculates the same hash value as was calculated before
the upcall?

> 
> Reported-at: 
> https://mail.openvswitch.org/pipermail/ovs-dev/2019-October/364062.html
> Signed-off-by: Tonghao Zhang 
> ---
>  include/uapi/linux/openvswitch.h |  2 ++
>  net/openvswitch/datapath.c   | 31 ++-
>  net/openvswitch/datapath.h   |  3 +++
>  3 files changed, 35 insertions(+), 1 deletion(-)
> 
> diff --git a/include/uapi/linux/openvswitch.h 
> b/include/uapi/linux/openvswitch.h
> index 1887a451c388..1c58e019438e 100644
> --- a/include/uapi/linux/openvswitch.h
> +++ b/include/uapi/linux/openvswitch.h
> @@ -170,6 +170,7 @@ enum ovs_packet_cmd {
>   * output port is actually a tunnel port. Contains the output tunnel key
>   * extracted from the packet as nested %OVS_TUNNEL_KEY_ATTR_* attributes.
>   * @OVS_PACKET_ATTR_MRU: Present for an %OVS_PACKET_CMD_ACTION and
> + * @OVS_PACKET_ATTR_HASH: Packet hash info (e.g. hash, sw_hash and l4_hash 
> in skb)
>   * @OVS_PACKET_ATTR_LEN: Packet size before truncation.
>   * %OVS_PACKET_ATTR_USERSPACE action specify the Maximum received fragment
>   * size.
> @@ -190,6 +191,7 @@ enum ovs_packet_attr {
>   OVS_PACKET_ATTR_PROBE,  /* Packet operation is a feature probe,
>  error logging should be suppressed. */
>   OVS_PACKET_ATTR_MRU,/* Maximum received IP fragment size. */
> + OVS_PACKET_ATTR_HASH,   /* Packet hash. */
>   OVS_PACKET_ATTR_LEN,/* Packet size before truncation. */
>   __OVS_PACKET_ATTR_MAX
>  };
> diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
> index 2088619c03f0..f938c43e3085 100644
> --- a/net/openvswitch/datapath.c
> +++ b/net/openvswitch/datapath.c
> @@ -350,7 +350,8 @@ static size_t upcall_msg_size(const struct dp_upcall_info 
> *upcall_info,
>   size_t size = NLMSG_ALIGN(sizeof(struct ovs_header))
>   + nla_total_size(hdrlen) /* OVS_PACKET_ATTR_PACKET */
>   + nla_total_size(ovs_key_attr_size()) /* OVS_PACKET_ATTR_KEY */
> - + nla_total_size(sizeof(unsigned int)); /* OVS_PACKET_ATTR_LEN 
> */
> + + nla_total_size(sizeof(unsigned int)) /* OVS_PACKET_ATTR_LEN */
> + + nla_total_size(sizeof(u64)); /* OVS_PACKET_ATTR_HASH */
>  
>   /* OVS_PACKET_ATTR_USERDATA */
>   if (upcall_info->userdata)
> @@ -393,6 +394,7 @@ static int queue_userspace_packet(struct datapath *dp, 
> struct sk_buff *skb,
>   size_t len;
>   unsigned int hlen;
>   int err, dp_ifindex;
> + u64 hash;
>  
>   dp_ifindex = get_dpifindex(dp);
>   if (!dp_ifindex)
> @@ -504,6 +506,24 @@ static int queue_userspace_packet(struct datapath *dp, 
> struct sk_buff *skb,
>   pad_packet(dp, user_skb);
>   }
>  
> + if (skb_get_hash_raw(skb)) {
> + hash = skb_get_hash_raw(skb);
> +
> + if (skb->sw_hash)
> 

[ovs-dev] [PATCH net-next] net: openvswitch: add hash info to upcall

[xiangxia . m . yue]

From: Tonghao Zhang 

When using the kernel datapath, the upcall don't
add skb hash info relatived. That will introduce
some problem, because the hash of skb is very
important (e.g. vxlan module uses it for udp src port,
tx queue selection on tx path.).

For example, there will be one upcall, without information
skb hash, to ovs-vswitchd, for the first packet of one tcp
session. When kernel sents the tcp packets, the hash is
random for a tcp socket:

tcp_v4_connect
  -> sk_set_txhash (is random)

__tcp_transmit_skb
  -> skb_set_hash_from_sk

Then the udp src port of first tcp packet is different
from rest packets. The topo is shown.

$ ovs-vsctl add-br br-int
$ ovs-vsctl add-port br-int vxl0 -- \
set Interface vxl0 type=vxlan options:key=100 
options:remote_ip=1.1.1.200

$ __tap is internal type on host
$ or tap net device for VM/Dockers
$ ovs-vsctl add-port br-int __tap

+---+  +-+
|   Docker/VMs  |  | ovs-vswitchd|
++--+  +-+
 |   ^|
 |   ||
 |   |  upcallv recalculate packet hash
 | +-++--+
 |  tap netdev | |   vxlan modules
 +---> +-->  Open vSwitch ko   --+--->
   internal type   | |
   +-+

Reported-at: 
https://mail.openvswitch.org/pipermail/ovs-dev/2019-October/364062.html
Signed-off-by: Tonghao Zhang 
---
 include/uapi/linux/openvswitch.h |  2 ++
 net/openvswitch/datapath.c   | 31 ++-
 net/openvswitch/datapath.h   |  3 +++
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/include/uapi/linux/openvswitch.h b/include/uapi/linux/openvswitch.h
index 1887a451c388..1c58e019438e 100644
--- a/include/uapi/linux/openvswitch.h
+++ b/include/uapi/linux/openvswitch.h
@@ -170,6 +170,7 @@ enum ovs_packet_cmd {
  * output port is actually a tunnel port. Contains the output tunnel key
  * extracted from the packet as nested %OVS_TUNNEL_KEY_ATTR_* attributes.
  * @OVS_PACKET_ATTR_MRU: Present for an %OVS_PACKET_CMD_ACTION and
+ * @OVS_PACKET_ATTR_HASH: Packet hash info (e.g. hash, sw_hash and l4_hash in 
skb)
  * @OVS_PACKET_ATTR_LEN: Packet size before truncation.
  * %OVS_PACKET_ATTR_USERSPACE action specify the Maximum received fragment
  * size.
@@ -190,6 +191,7 @@ enum ovs_packet_attr {
OVS_PACKET_ATTR_PROBE,  /* Packet operation is a feature probe,
   error logging should be suppressed. */
OVS_PACKET_ATTR_MRU,/* Maximum received IP fragment size. */
+   OVS_PACKET_ATTR_HASH,   /* Packet hash. */
OVS_PACKET_ATTR_LEN,/* Packet size before truncation. */
__OVS_PACKET_ATTR_MAX
 };
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index 2088619c03f0..f938c43e3085 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -350,7 +350,8 @@ static size_t upcall_msg_size(const struct dp_upcall_info 
*upcall_info,
size_t size = NLMSG_ALIGN(sizeof(struct ovs_header))
+ nla_total_size(hdrlen) /* OVS_PACKET_ATTR_PACKET */
+ nla_total_size(ovs_key_attr_size()) /* OVS_PACKET_ATTR_KEY */
-   + nla_total_size(sizeof(unsigned int)); /* OVS_PACKET_ATTR_LEN 
*/
+   + nla_total_size(sizeof(unsigned int)) /* OVS_PACKET_ATTR_LEN */
+   + nla_total_size(sizeof(u64)); /* OVS_PACKET_ATTR_HASH */
 
/* OVS_PACKET_ATTR_USERDATA */
if (upcall_info->userdata)
@@ -393,6 +394,7 @@ static int queue_userspace_packet(struct datapath *dp, 
struct sk_buff *skb,
size_t len;
unsigned int hlen;
int err, dp_ifindex;
+   u64 hash;
 
dp_ifindex = get_dpifindex(dp);
if (!dp_ifindex)
@@ -504,6 +506,24 @@ static int queue_userspace_packet(struct datapath *dp, 
struct sk_buff *skb,
pad_packet(dp, user_skb);
}
 
+   if (skb_get_hash_raw(skb)) {
+   hash = skb_get_hash_raw(skb);
+
+   if (skb->sw_hash)
+   hash |= OVS_PACKET_HASH_SW;
+
+   if (skb->l4_hash)
+   hash |= OVS_PACKET_HASH_L4;
+
+   if (nla_put(user_skb, OVS_PACKET_ATTR_HASH,
+   sizeof (u64), )) {
+   err = -ENOBUFS;
+   goto out;
+   }
+
+   pad_packet(dp, user_skb);
+   }
+
/* Only reserve room for attribute header, packet data is added
 * in skb_zerocopy() */
if (!(nla = nla_reserve(user_skb, OVS_PACKET_ATTR_PACKET, 0))) {
@@ -543,6 +563,7 @@ static int ovs_packet_cmd_execute(struct sk_buff *skb, 
struct genl_info *info)