[virtio-comment] [PATCH] virtio-net: Fix virtio_net_hdr struct size when VIRTIO_NET_F_HASH_REPORT is negotiated.

[virtio-comment] [PATCH] virtio-net: Fix virtio_net_hdr struct size when VIRTIO_NET_F_HASH_REPORT is negotiated.

[Cyril Germond]

Hard-coded references to the size of virtio_net_hdr strut are wrong when
VIRTIO_NET_HASH_REPORT feature is negotiated.

Changelog:
v1->v2: Fixed wording syntax
v2->v3: Rebase

Signed-off-by: Cyril Germond <cgermond@kalray.eu>
---
 content.tex    | 10 ++++++----
 split-ring.tex |  3 ++-
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/content.tex b/content.tex
index 91ba76c..61bc09c 100644
--- a/content.tex
+++ b/content.tex
@@ -3622,8 +3622,8 @@ \subsubsection{Setting Up Receive Buffers}\label{sec:Device Types / Network Devi
 features are used, the maximum incoming packet
 will be to 65550 bytes long (the maximum size of a
 TCP or UDP packet, plus the 14 byte ethernet header), otherwise
-1514 bytes.  The 12-byte struct virtio_net_hdr is prepended to this,
-making for 65562 or 1526 bytes.
+1514 bytes.  The struct virtio_net_hdr (the length of which depends on VIRTIO_NET_F_HASH_REPORT
+feature negotiation) is prepended to this.
 
 \drivernormative{\paragraph}{Setting Up Receive Buffers}{Device Types / Network Device / Device Operation / Setting Up Receive Buffers}
 
@@ -3632,9 +3632,11 @@ \subsubsection{Setting Up Receive Buffers}\label{sec:Device Types / Network Devi
   \begin{itemize}
     \item If VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6, VIRTIO_NET_F_GUEST_UFO,
 	VIRTIO_NET_F_GUEST_USO4 or VIRTIO_NET_F_GUEST_USO6 are negotiated, the driver SHOULD populate
-      the receive queue(s) with buffers of at least 65562 bytes.
+      the receive queue(s) with buffers of at least 65570 bytes
+      if VIRTIO_NET_F_HASH_REPORT is negotiated, 65562 bytes otherwise.
     \item Otherwise, the driver SHOULD populate the receive queue(s)
-      with buffers of at least 1526 bytes.
+      with buffers of at least 1534 bytes if VIRTIO_NET_F_HASH_REPORT
+      is negotiated, 1526 bytes otherwise.
   \end{itemize}
 \item If VIRTIO_NET_F_MRG_RXBUF is negotiated, each buffer MUST be at
 least the size of the struct virtio_net_hdr.
diff --git a/split-ring.tex b/split-ring.tex
index de94038..82e910f 100644
--- a/split-ring.tex
+++ b/split-ring.tex
@@ -127,7 +127,8 @@ \subsection{Legacy Interfaces: A Note on Virtqueue Endianness}\label{sec:Basic F
 
 \subsection{Message Framing}\label{sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing}
 The framing of messages with descriptors is
-independent of the contents of the buffers. For example, a network
+independent of the contents of the buffers. For example, if
+VIRTIO_NET_F_HASH_REPORT has not been negotiated, a network
 transmit buffer consists of a 12 byte header followed by the network
 packet. This could be most simply placed in the descriptor table as a
 12 byte output descriptor followed by a 1514 byte output descriptor,
-- 
2.25.1






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[virtio-comment] RE: [PATCH] virtio-net: Fix virtio_net_hdr struct size when VIRTIO_NET_F_HASH_REPORT is negotiated.

[Cyril Germond]

Hello
It seems this proposal has not received feedback from virtio-net folks.
What should we do with it ?
Thanks

-----Original Message-----
From: Cyril Germond <cgermond@kalray.eu> 
Sent: Monday, November 21, 2022 10:03 AM
To: virtio-comment@lists.oasis-open.org
Cc: Cyril Germond <cgermond@kalray.eu>
Subject: [PATCH] virtio-net: Fix virtio_net_hdr struct size when VIRTIO_NET_F_HASH_REPORT is negotiated.

Hard-coded references to the size of virtio_net_hdr strut are wrong when VIRTIO_NET_HASH_REPORT feature is negotiated.

Changelog:
v1->v2: Fixed wording syntax
v2->v3: Rebase

Signed-off-by: Cyril Germond <cgermond@kalray.eu>
---
 content.tex    | 10 ++++++----
 split-ring.tex |  3 ++-
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/content.tex b/content.tex
index 91ba76c..61bc09c 100644
--- a/content.tex
+++ b/content.tex
@@ -3622,8 +3622,8 @@ \subsubsection{Setting Up Receive Buffers}\label{sec:Device Types / Network Devi  features are used, the maximum incoming packet  will be to 65550 bytes long (the maximum size of a  TCP or UDP packet, plus the 14 byte ethernet header), otherwise
-1514 bytes.  The 12-byte struct virtio_net_hdr is prepended to this, -making for 65562 or 1526 bytes.
+1514 bytes.  The struct virtio_net_hdr (the length of which depends on 
+VIRTIO_NET_F_HASH_REPORT feature negotiation) is prepended to this.
 
 \drivernormative{\paragraph}{Setting Up Receive Buffers}{Device Types / Network Device / Device Operation / Setting Up Receive Buffers}
 
@@ -3632,9 +3632,11 @@ \subsubsection{Setting Up Receive Buffers}\label{sec:Device Types / Network Devi
   \begin{itemize}
     \item If VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6, VIRTIO_NET_F_GUEST_UFO,
 	VIRTIO_NET_F_GUEST_USO4 or VIRTIO_NET_F_GUEST_USO6 are negotiated, the driver SHOULD populate
-      the receive queue(s) with buffers of at least 65562 bytes.
+      the receive queue(s) with buffers of at least 65570 bytes
+      if VIRTIO_NET_F_HASH_REPORT is negotiated, 65562 bytes otherwise.
     \item Otherwise, the driver SHOULD populate the receive queue(s)
-      with buffers of at least 1526 bytes.
+      with buffers of at least 1534 bytes if VIRTIO_NET_F_HASH_REPORT
+      is negotiated, 1526 bytes otherwise.
   \end{itemize}
 \item If VIRTIO_NET_F_MRG_RXBUF is negotiated, each buffer MUST be at  least the size of the struct virtio_net_hdr.
diff --git a/split-ring.tex b/split-ring.tex index de94038..82e910f 100644
--- a/split-ring.tex
+++ b/split-ring.tex
@@ -127,7 +127,8 @@ \subsection{Legacy Interfaces: A Note on Virtqueue Endianness}\label{sec:Basic F
 
 \subsection{Message Framing}\label{sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing}  The framing of messages with descriptors is -independent of the contents of the buffers. For example, a network
+independent of the contents of the buffers. For example, if 
+VIRTIO_NET_F_HASH_REPORT has not been negotiated, a network
 transmit buffer consists of a 12 byte header followed by the network  packet. This could be most simply placed in the descriptor table as a
 12 byte output descriptor followed by a 1514 byte output descriptor,
--
2.25.1






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Re: [virtio-comment] RE: [PATCH] virtio-net: Fix virtio_net_hdr struct size when VIRTIO_NET_F_HASH_REPORT is negotiated.

[Michael S. Tsirkin]

On Wed, May 03, 2023 at 01:39:59PM +0000, Cyril Germond wrote:
> Hello
> It seems this proposal has not received feedback from virtio-net folks.
> What should we do with it ?
> Thanks

Request a vote to resolve this as described at:
https://github.com/oasis-tcs/virtio-spec#use-of-github-issues

> -----Original Message-----
> From: Cyril Germond <cgermond@kalray.eu> 
> Sent: Monday, November 21, 2022 10:03 AM
> To: virtio-comment@lists.oasis-open.org
> Cc: Cyril Germond <cgermond@kalray.eu>
> Subject: [PATCH] virtio-net: Fix virtio_net_hdr struct size when VIRTIO_NET_F_HASH_REPORT is negotiated.
> 
> Hard-coded references to the size of virtio_net_hdr strut are wrong when VIRTIO_NET_HASH_REPORT feature is negotiated.
> 
> Changelog:
> v1->v2: Fixed wording syntax
> v2->v3: Rebase
> 
> Signed-off-by: Cyril Germond <cgermond@kalray.eu>
> ---
>  content.tex    | 10 ++++++----
>  split-ring.tex |  3 ++-
>  2 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/content.tex b/content.tex
> index 91ba76c..61bc09c 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -3622,8 +3622,8 @@ \subsubsection{Setting Up Receive Buffers}\label{sec:Device Types / Network Devi  features are used, the maximum incoming packet  will be to 65550 bytes long (the maximum size of a  TCP or UDP packet, plus the 14 byte ethernet header), otherwise
> -1514 bytes.  The 12-byte struct virtio_net_hdr is prepended to this, -making for 65562 or 1526 bytes.
> +1514 bytes.  The struct virtio_net_hdr (the length of which depends on 
> +VIRTIO_NET_F_HASH_REPORT feature negotiation) is prepended to this.
>  
>  \drivernormative{\paragraph}{Setting Up Receive Buffers}{Device Types / Network Device / Device Operation / Setting Up Receive Buffers}
>  
> @@ -3632,9 +3632,11 @@ \subsubsection{Setting Up Receive Buffers}\label{sec:Device Types / Network Devi
>    \begin{itemize}
>      \item If VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6, VIRTIO_NET_F_GUEST_UFO,
>  	VIRTIO_NET_F_GUEST_USO4 or VIRTIO_NET_F_GUEST_USO6 are negotiated, the driver SHOULD populate
> -      the receive queue(s) with buffers of at least 65562 bytes.
> +      the receive queue(s) with buffers of at least 65570 bytes
> +      if VIRTIO_NET_F_HASH_REPORT is negotiated, 65562 bytes otherwise.
>      \item Otherwise, the driver SHOULD populate the receive queue(s)
> -      with buffers of at least 1526 bytes.
> +      with buffers of at least 1534 bytes if VIRTIO_NET_F_HASH_REPORT
> +      is negotiated, 1526 bytes otherwise.
>    \end{itemize}
>  \item If VIRTIO_NET_F_MRG_RXBUF is negotiated, each buffer MUST be at  least the size of the struct virtio_net_hdr.
> diff --git a/split-ring.tex b/split-ring.tex index de94038..82e910f 100644
> --- a/split-ring.tex
> +++ b/split-ring.tex
> @@ -127,7 +127,8 @@ \subsection{Legacy Interfaces: A Note on Virtqueue Endianness}\label{sec:Basic F
>  
>  \subsection{Message Framing}\label{sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing}  The framing of messages with descriptors is -independent of the contents of the buffers. For example, a network
> +independent of the contents of the buffers. For example, if 
> +VIRTIO_NET_F_HASH_REPORT has not been negotiated, a network
>  transmit buffer consists of a 12 byte header followed by the network  packet. This could be most simply placed in the descriptor table as a
>  12 byte output descriptor followed by a 1514 byte output descriptor,
> --
> 2.25.1
> 
> 
> 
> 
> 
> 
> This publicly archived list offers a means to provide input to the
> OASIS Virtual I/O Device (VIRTIO) TC.
> 
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> to minimize spam in the list archive, subscription is required
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RE: [virtio-comment] RE: [PATCH] virtio-net: Fix virtio_net_hdr struct size when VIRTIO_NET_F_HASH_REPORT is negotiated.

[Cyril Germond]

OK thanks

Fixes: https://github.com/oasis-tcs/virtio-spec/issues/170

-----Original Message-----
From: Michael S. Tsirkin <mst@redhat.com> 
Sent: Wednesday, May 3, 2023 4:27 PM
To: Cyril Germond <cgermond@kalrayinc.com>
Cc: virtio-comment@lists.oasis-open.org
Subject: Re: [virtio-comment] RE: [PATCH] virtio-net: Fix virtio_net_hdr struct size when VIRTIO_NET_F_HASH_REPORT is negotiated.

On Wed, May 03, 2023 at 01:39:59PM +0000, Cyril Germond wrote:
> Hello
> It seems this proposal has not received feedback from virtio-net folks.
> What should we do with it ?
> Thanks

Request a vote to resolve this as described at:
https://github.com/oasis-tcs/virtio-spec#use-of-github-issues

> -----Original Message-----
> From: Cyril Germond <cgermond@kalray.eu>
> Sent: Monday, November 21, 2022 10:03 AM
> To: virtio-comment@lists.oasis-open.org
> Cc: Cyril Germond <cgermond@kalray.eu>
> Subject: [PATCH] virtio-net: Fix virtio_net_hdr struct size when VIRTIO_NET_F_HASH_REPORT is negotiated.
> 
> Hard-coded references to the size of virtio_net_hdr strut are wrong when VIRTIO_NET_HASH_REPORT feature is negotiated.
> 
> Changelog:
> v1->v2: Fixed wording syntax
> v2->v3: Rebase
> 
> Signed-off-by: Cyril Germond <cgermond@kalray.eu>
> ---
>  content.tex    | 10 ++++++----
>  split-ring.tex |  3 ++-
>  2 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/content.tex b/content.tex index 91ba76c..61bc09c 100644
> --- a/content.tex
> +++ b/content.tex
> @@ -3622,8 +3622,8 @@ \subsubsection{Setting Up Receive 
> Buffers}\label{sec:Device Types / Network Devi  features are used, the 
> maximum incoming packet  will be to 65550 bytes long (the maximum size 
> of a  TCP or UDP packet, plus the 14 byte ethernet header), otherwise
> -1514 bytes.  The 12-byte struct virtio_net_hdr is prepended to this, -making for 65562 or 1526 bytes.
> +1514 bytes.  The struct virtio_net_hdr (the length of which depends 
> +on VIRTIO_NET_F_HASH_REPORT feature negotiation) is prepended to this.
>  
>  \drivernormative{\paragraph}{Setting Up Receive Buffers}{Device Types 
> / Network Device / Device Operation / Setting Up Receive Buffers}
>  
> @@ -3632,9 +3632,11 @@ \subsubsection{Setting Up Receive Buffers}\label{sec:Device Types / Network Devi
>    \begin{itemize}
>      \item If VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6, VIRTIO_NET_F_GUEST_UFO,
>  	VIRTIO_NET_F_GUEST_USO4 or VIRTIO_NET_F_GUEST_USO6 are negotiated, the driver SHOULD populate
> -      the receive queue(s) with buffers of at least 65562 bytes.
> +      the receive queue(s) with buffers of at least 65570 bytes
> +      if VIRTIO_NET_F_HASH_REPORT is negotiated, 65562 bytes otherwise.
>      \item Otherwise, the driver SHOULD populate the receive queue(s)
> -      with buffers of at least 1526 bytes.
> +      with buffers of at least 1534 bytes if VIRTIO_NET_F_HASH_REPORT
> +      is negotiated, 1526 bytes otherwise.
>    \end{itemize}
>  \item If VIRTIO_NET_F_MRG_RXBUF is negotiated, each buffer MUST be at  least the size of the struct virtio_net_hdr.
> diff --git a/split-ring.tex b/split-ring.tex index de94038..82e910f 
> 100644
> --- a/split-ring.tex
> +++ b/split-ring.tex
> @@ -127,7 +127,8 @@ \subsection{Legacy Interfaces: A Note on Virtqueue 
> Endianness}\label{sec:Basic F
>  
>  \subsection{Message Framing}\label{sec:Basic Facilities of a Virtio 
> Device / Virtqueues / Message Framing}  The framing of messages with 
> descriptors is -independent of the contents of the buffers. For 
> example, a network
> +independent of the contents of the buffers. For example, if 
> +VIRTIO_NET_F_HASH_REPORT has not been negotiated, a network
>  transmit buffer consists of a 12 byte header followed by the network  
> packet. This could be most simply placed in the descriptor table as a
>  12 byte output descriptor followed by a 1514 byte output descriptor,
> --
> 2.25.1
> 
> 
> 
> 
> 
> 
> This publicly archived list offers a means to provide input to the 
> OASIS Virtual I/O Device (VIRTIO) TC.
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> In order to verify user consent to the Feedback License terms and to 
> minimize spam in the list archive, subscription is required before 
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Re: [virtio-comment] RE: [PATCH] virtio-net: Fix virtio_net_hdr struct size when VIRTIO_NET_F_HASH_REPORT is negotiated.

[Parav Pandit]

On 5/3/2023 9:39 AM, Cyril Germond wrote:
> From: Cyril Germond <cgermond@kalray.eu>
> Sent: Monday, November 21, 2022 10:03 AM
> 
> Hard-coded references to the size of virtio_net_hdr strut are wrong when VIRTIO_NET_HASH_REPORT feature is negotiated.
Please fix spelling,
s/strut/struct

Below changelog should be after "---", so that it doesnt become part of 
the commit log.
>   
>   \subsection{Message Framing}\label{sec:Basic Facilities of a Virtio Device / Virtqueues / Message Framing}  The framing of messages with descriptors is -independent of the contents of the buffers. For example, a network
> +independent of the contents of the buffers. For example, if
> +VIRTIO_NET_F_HASH_REPORT has not been negotiated, a network
>   transmit buffer consists of a 12 byte header followed by the network  packet. This could be most simply placed in the descriptor table as a
>   12 byte output descriptor followed by a 1514 byte output descriptor,

Above change does not look correct as the example is for the Tx.
and HASH_REPORT is for the RX.

Once you post the new version as v1 with above fixes, please update the 
link in the github issue as well.

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RE: [virtio-comment] RE: [PATCH] virtio-net: Fix virtio_net_hdr struct size when VIRTIO_NET_F_HASH_REPORT is negotiated.

[Cyril Germond]

Hello
I agree VIRTIO_NET_HASH_REPORT feature is for incoming packets path.
Nevertheless, it seems - at least to me but I may be wrong there - that the packet header structure data type - as described in chapter 5.1.6 Device Operation - is the same for the Rx and TX packets.
Thus, if VIRTIO_NET_HASH_REPORT feature is negotiated, even for a Rx only feature, , the same virtio_net_hdr structure size should be used for both Rx and TX packets. Am I wrong ?
Thanks,

-----Original Message-----
From: Parav Pandit <parav@nvidia.com> 
Sent: Wednesday, May 3, 2023 6:33 PM
To: Cyril Germond <cgermond@kalrayinc.com>; virtio-comment@lists.oasis-open.org
Subject: Re: [virtio-comment] RE: [PATCH] virtio-net: Fix virtio_net_hdr struct size when VIRTIO_NET_F_HASH_REPORT is negotiated.



On 5/3/2023 9:39 AM, Cyril Germond wrote:
> From: Cyril Germond <cgermond@kalray.eu>
> Sent: Monday, November 21, 2022 10:03 AM
> 
> Hard-coded references to the size of virtio_net_hdr strut are wrong when VIRTIO_NET_HASH_REPORT feature is negotiated.
Please fix spelling,
s/strut/struct

Below changelog should be after "---", so that it doesnt become part of the commit log.
>   
>   \subsection{Message Framing}\label{sec:Basic Facilities of a Virtio 
> Device / Virtqueues / Message Framing}  The framing of messages with 
> descriptors is -independent of the contents of the buffers. For 
> example, a network
> +independent of the contents of the buffers. For example, if 
> +VIRTIO_NET_F_HASH_REPORT has not been negotiated, a network
>   transmit buffer consists of a 12 byte header followed by the network  packet. This could be most simply placed in the descriptor table as a
>   12 byte output descriptor followed by a 1514 byte output descriptor,

Above change does not look correct as the example is for the Tx.
and HASH_REPORT is for the RX.

Once you post the new version as v1 with above fixes, please update the link in the github issue as well.









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RE: [virtio-comment] RE: [PATCH] virtio-net: Fix virtio_net_hdr struct size when VIRTIO_NET_F_HASH_REPORT is negotiated.

[Parav Pandit]

> From: Cyril Germond <cgermond@kalrayinc.com>
> Sent: Thursday, May 4, 2023 1:17 PM
> 
> Hello
> I agree VIRTIO_NET_HASH_REPORT feature is for incoming packets path.
> Nevertheless, it seems - at least to me but I may be wrong there - that the
> packet header structure data type - as described in chapter 5.1.6 Device
> Operation - is the same for the Rx and TX packets.
> Thus, if VIRTIO_NET_HASH_REPORT feature is negotiated, even for a Rx only
> feature, , the same virtio_net_hdr structure size should be used for both Rx and
> TX packets. Am I wrong ?
> Thanks,

Given the current state of the driver usage and spec it is the same size for tx and rx.

However, the delta change you proposed is modifying a generic non-network device-specific example.

We need a normative line in the section both sections.

5.1.6.2.1 Driver Requirements: Packet Transmission,
5.1.6.2.2 Device Requirements: Packet Transmission

Something like,
For the transmit virtuqueue the driver MUST prepare \field{struct virtio_net_hdr} to be the same size as that of receive virtqueue.

The device MUST consider \field{struct virtio_net_hdr} size for the transmit and the receive virtqueue to be of the same size.