diff mbox

[net,3/3] Drivers: net: hyperv: Address UDP checksum issues

Message ID 1396986371-12137-4-git-send-email-kys@microsoft.com
State Changes Requested, archived
Delegated to: David Miller
Headers show

Commit Message

KY Srinivasan April 8, 2014, 7:46 p.m. UTC 
ws2008r2 does not support UDP checksum offload. Thus, we cannnot turn on
UDP offload in the host. Also, on ws2012 and ws2012 r2, there appear to be
an issue with UDP checksum offload.
Fix this issue by computing the UDP checksum in the Hyper-V driver.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
---
 drivers/net/hyperv/hyperv_net.h   |    1 +
 drivers/net/hyperv/netvsc_drv.c   |   19 ++++++++++++++++++-
 drivers/net/hyperv/rndis_filter.c |   12 +++++++++++-
 3 files changed, 30 insertions(+), 2 deletions(-)

Comments

David Miller April 9, 2014, 5:01 p.m. UTC | #1 
From: "K. Y. Srinivasan" <kys@microsoft.com>
Date: Tue,  8 Apr 2014 12:46:11 -0700

>  	} else if (net_trans_info & INFO_UDP) {
> -		csum_info->transmit.udp_checksum = 1;
> +		/* UDP checksum offload is not supported on ws2008r2.
> +		 * Furthermore, on ws2012 and ws2012r2, there are some
> +		 * issues with udp checksum offload from Linux guests.
> +		 * (these are host issues).
> +		 * For now compute the checksum here.
> +		 */
> +		struct udphdr *uh = udp_hdr(skb);
> +		u16 udp_len = ntohs(uh->len);
> +
> +		uh->check = 0;
> +		uh->check = csum_tcpudp_magic(ip_hdr(skb)->saddr,
> +					      ip_hdr(skb)->daddr,
> +					      udp_len, IPPROTO_UDP,
> +					      csum_partial(uh, udp_len, 0));
> +		if (uh->check == 0)
> +			uh->check = CSUM_MANGLED_0;
> +
> +		csum_info->transmit.udp_checksum = 0;

You absolutely cannot mangle packet header contents without first
COW'ing the SKB to make sure it's writable.

Otherwise network taps like tcpdump, and any other entity with a reference
to the packet, can see inconsistent state.
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KY Srinivasan April 9, 2014, 6:08 p.m. UTC | #2 
> -----Original Message-----
> From: David Miller [mailto:davem@davemloft.net]
> Sent: Wednesday, April 9, 2014 10:01 AM
> To: KY Srinivasan
> Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org;
> devel@linuxdriverproject.org; olaf@aepfle.de; apw@canonical.com;
> jasowang@redhat.com
> Subject: Re: [PATCH net 3/3] Drivers: net: hyperv: Address UDP checksum
> issues
> 
> From: "K. Y. Srinivasan" <kys@microsoft.com>
> Date: Tue,  8 Apr 2014 12:46:11 -0700
> 
> >  	} else if (net_trans_info & INFO_UDP) {
> > -		csum_info->transmit.udp_checksum = 1;
> > +		/* UDP checksum offload is not supported on ws2008r2.
> > +		 * Furthermore, on ws2012 and ws2012r2, there are some
> > +		 * issues with udp checksum offload from Linux guests.
> > +		 * (these are host issues).
> > +		 * For now compute the checksum here.
> > +		 */
> > +		struct udphdr *uh = udp_hdr(skb);
> > +		u16 udp_len = ntohs(uh->len);
> > +
> > +		uh->check = 0;
> > +		uh->check = csum_tcpudp_magic(ip_hdr(skb)->saddr,
> > +					      ip_hdr(skb)->daddr,
> > +					      udp_len, IPPROTO_UDP,
> > +					      csum_partial(uh, udp_len, 0));
> > +		if (uh->check == 0)
> > +			uh->check = CSUM_MANGLED_0;
> > +
> > +		csum_info->transmit.udp_checksum = 0;
> 
> You absolutely cannot mangle packet header contents without first COW'ing
> the SKB to make sure it's writable.
> 
> Otherwise network taps like tcpdump, and any other entity with a reference
> to the packet, can see inconsistent state.

Thanks Dave. I will COW the SKB before changing the checksum value. I do have a question though.
I looked at a bunch of hardware drivers and they modify the header information, specially checksum
field and I could not see where they had COWed the skb. I was grepping for skb_cow in these drivers.


Regards,

K. Y
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David Miller April 9, 2014, 6:36 p.m. UTC | #3 
From: KY Srinivasan <kys@microsoft.com>
Date: Wed, 9 Apr 2014 18:08:47 +0000

> Thanks Dave. I will COW the SKB before changing the checksum
> value. I do have a question though.  I looked at a bunch of hardware
> drivers and they modify the header information, specially checksum
> field and I could not see where they had COWed the skb. I was
> grepping for skb_cow in these drivers.

Look for skb_cow_head(), for example, the tg3.c driver uses this.


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KY Srinivasan April 9, 2014, 6:39 p.m. UTC | #4 
> -----Original Message-----
> From: David Miller [mailto:davem@davemloft.net]
> Sent: Wednesday, April 9, 2014 11:37 AM
> To: KY Srinivasan
> Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org;
> devel@linuxdriverproject.org; olaf@aepfle.de; apw@canonical.com;
> jasowang@redhat.com
> Subject: Re: [PATCH net 3/3] Drivers: net: hyperv: Address UDP checksum
> issues
> 
> From: KY Srinivasan <kys@microsoft.com>
> Date: Wed, 9 Apr 2014 18:08:47 +0000
> 
> > Thanks Dave. I will COW the SKB before changing the checksum value. I
> > do have a question though.  I looked at a bunch of hardware drivers
> > and they modify the header information, specially checksum field and I
> > could not see where they had COWed the skb. I was grepping for skb_cow
> > in these drivers.
> 
> Look for skb_cow_head(), for example, the tg3.c driver uses this.
> 
Thank you. I will update this patch. Do you want me to resend the whole set or just
this patch.

K. Y
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David Miller April 9, 2014, 6:42 p.m. UTC | #5 
From: KY Srinivasan <kys@microsoft.com>
Date: Wed, 9 Apr 2014 18:39:57 +0000

> 
> 
>> -----Original Message-----
>> From: David Miller [mailto:davem@davemloft.net]
>> Sent: Wednesday, April 9, 2014 11:37 AM
>> To: KY Srinivasan
>> Cc: netdev@vger.kernel.org; linux-kernel@vger.kernel.org;
>> devel@linuxdriverproject.org; olaf@aepfle.de; apw@canonical.com;
>> jasowang@redhat.com
>> Subject: Re: [PATCH net 3/3] Drivers: net: hyperv: Address UDP checksum
>> issues
>> 
>> From: KY Srinivasan <kys@microsoft.com>
>> Date: Wed, 9 Apr 2014 18:08:47 +0000
>> 
>> > Thanks Dave. I will COW the SKB before changing the checksum value. I
>> > do have a question though.  I looked at a bunch of hardware drivers
>> > and they modify the header information, specially checksum field and I
>> > could not see where they had COWed the skb. I was grepping for skb_cow
>> > in these drivers.
>> 
>> Look for skb_cow_head(), for example, the tg3.c driver uses this.
>> 
> Thank you. I will update this patch. Do you want me to resend the whole set or just
> this patch.

You never need to ask me this.

Always, when there is an update to any part of a series, re-submit the entire
series.
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diff mbox

Patch

diff --git a/drivers/net/hyperv/hyperv_net.h b/drivers/net/hyperv/hyperv_net.h
index 13010b4..d18f711d 100644
--- a/drivers/net/hyperv/hyperv_net.h
+++ b/drivers/net/hyperv/hyperv_net.h
@@ -747,6 +747,7 @@  struct ndis_oject_header {
 #define NDIS_TCP_LARGE_SEND_OFFLOAD_IPV4	0
 #define NDIS_TCP_LARGE_SEND_OFFLOAD_IPV6	1
 
+#define VERSION_4_OFFLOAD_SIZE			22
 /*
  * New offload OIDs for NDIS 6
  */
diff --git a/drivers/net/hyperv/netvsc_drv.c b/drivers/net/hyperv/netvsc_drv.c
index 6f39baa..8e3919b 100644
--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c
@@ -398,7 +398,24 @@  static int netvsc_start_xmit(struct sk_buff *skb, struct net_device *net)
 		csum_info->transmit.tcp_checksum = 1;
 		csum_info->transmit.tcp_header_offset = hdr_offset;
 	} else if (net_trans_info & INFO_UDP) {
-		csum_info->transmit.udp_checksum = 1;
+		/* UDP checksum offload is not supported on ws2008r2.
+		 * Furthermore, on ws2012 and ws2012r2, there are some
+		 * issues with udp checksum offload from Linux guests.
+		 * (these are host issues).
+		 * For now compute the checksum here.
+		 */
+		struct udphdr *uh = udp_hdr(skb);
+		u16 udp_len = ntohs(uh->len);
+
+		uh->check = 0;
+		uh->check = csum_tcpudp_magic(ip_hdr(skb)->saddr,
+					      ip_hdr(skb)->daddr,
+					      udp_len, IPPROTO_UDP,
+					      csum_partial(uh, udp_len, 0));
+		if (uh->check == 0)
+			uh->check = CSUM_MANGLED_0;
+
+		csum_info->transmit.udp_checksum = 0;
 	}
 	goto do_send;
 
diff --git a/drivers/net/hyperv/rndis_filter.c b/drivers/net/hyperv/rndis_filter.c
index 4a37e3d..143a98c 100644
--- a/drivers/net/hyperv/rndis_filter.c
+++ b/drivers/net/hyperv/rndis_filter.c
@@ -641,6 +641,16 @@  int rndis_filter_set_offload_params(struct hv_device *hdev,
 	struct rndis_set_complete *set_complete;
 	u32 extlen = sizeof(struct ndis_offload_params);
 	int ret, t;
+	u32 vsp_version = nvdev->nvsp_version;
+
+	if (vsp_version <= NVSP_PROTOCOL_VERSION_4) {
+		extlen = VERSION_4_OFFLOAD_SIZE;
+		/* On NVSP_PROTOCOL_VERSION_4 and below, we do not support
+		 * UDP checksum offload.
+		 */
+		req_offloads->udp_ip_v4_csum = 0;
+		req_offloads->udp_ip_v6_csum = 0;
+	}
 
 	request = get_rndis_request(rdev, RNDIS_MSG_SET,
 		RNDIS_MESSAGE_SIZE(struct rndis_set_request) + extlen);
@@ -674,7 +684,7 @@  int rndis_filter_set_offload_params(struct hv_device *hdev,
 	} else {
 		set_complete = &request->response_msg.msg.set_complete;
 		if (set_complete->status != RNDIS_STATUS_SUCCESS) {
-			netdev_err(ndev, "Fail to set MAC on host side:0x%x\n",
+			netdev_err(ndev, "Fail to set offload on host side:0x%x\n",
 				   set_complete->status);
 			ret = -EINVAL;
 		}