[virtio-dev] [PATCH v6 0/8] Rename queue index to queue number

[virtio-dev] [PATCH v6 0/8] Rename queue index to queue number

[Parav Pandit]

1. Currently, virtqueue is identified between driver and device
interchangeably using either number of index terminology.

2. Between PCI and MMIO transport the queue size (depth) is
defined as queue_size and QueueNum respectively.

To avoid confusion and to have consistency, unify them to use as Number.

Solution:
a. Use virtqueue number description, and rename MMIO register as QueueSize.
b. Replace virtqueue index to virtqueue number
c. RSS area of virtio net has inherited some logic, describe it
using abstract rq_handle.

Patch summary:
patch-1 introduce vq number as generic term
patch-2 renames index to number for pci transport
patch-3 renames mmio register from Num to Size
patch-4 renames index to number for mmio transport
patch-5 renames num field to size for ccw transport
patch-6 renames index field to queue_select for ccw transport
patch-7 for virtio-net removes duplicate example from requirements
patch-8 for virtio-net updates rss description to use vq number

This series only improves the documentation, it does not change any
transport or device functionality.

Please review.
This series fixes the issue [1].

[1] https://github.com/oasis-tcs/virtio-spec/issues/163

---
changelog:
v5->v6:
- moved the vq number description from middle of vq operation
  to beginning of vq introduction
v4->v5:
- fixed accidental removal of "unclassifed packets".
- simplfied text around indirection_table mask
- removed rss_rq_id references as indirection table and
  unclassified_queue data type is self explanatory
v3->v4:
- moved note to comment for ccw
- renamed rq_handle to rss_rq_id
- moved rss_rq_id next to rss_config structure
- define rss_config structure using rss_rq_id
v2->v3:
- addressed comments from Michael
- added previous definitions for ccw fields
- moved rq_handle definition before using it
- added first patch to describe vq number
- updated pci for available buffer notification section
v1->v2:
- added patches for virtio net for rss area
- added patches for covering ccw transport
- added missing entries to refer in mmio transport


Parav Pandit (8):
  content: Add vq number text
  transport-pci: Refer to the vq by its number
  transport-mmio: Rename QueueNum register
  transport-mmio: Refer to the vq by its number
  transport-ccw: Rename queue depth/size to other transports
  transport-ccw: Refer to the vq by its number
  virtio-net: Avoid duplicate receive queue example
  virtio-net: Describe RSS using rss rq id

 content.tex                      |  3 ++
 device-types/net/description.tex | 28 +++++++++++-----
 transport-ccw.tex                | 27 ++++++++-------
 transport-mmio.tex               | 56 +++++++++++++++++++-------------
 transport-pci.tex                | 14 ++++----
 5 files changed, 80 insertions(+), 48 deletions(-)

-- 
2.26.2


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[virtio-dev] [PATCH v6 1/8] content: Add vq number text

[Parav Pandit]

Introduce vq number and its range so that subsequent patches can refer
to it.

Fixes: https://github.com/oasis-tcs/virtio-spec/issues/163
Signed-off-by: Parav Pandit <parav@nvidia.com>
---
changelog:
v5->v6:
- moved description close to introduction, it was in middle of
  queue data transfer description
v2->v3:
- new patch
---
 content.tex | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/content.tex b/content.tex
index cff548a..5171c12 100644
--- a/content.tex
+++ b/content.tex
@@ -298,6 +298,9 @@ \section{Virtqueues}\label{sec:Basic Facilities of a Virtio Device / Virtqueues}
 virtqueues\footnote{For example, the simplest network device has one virtqueue for
 transmit and one for receive.}.
 
+Each virtqueue is identified by a vq number or also referred
+to as a virtqueue number; vq number range is from 0 to 65535.
+
 Driver makes requests available to device by adding
 an available buffer to the queue, i.e., adding a buffer
 describing the request to a virtqueue, and optionally triggering
-- 
2.26.2


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[virtio-dev] [PATCH v6 2/8] transport-pci: Refer to the vq by its number

[Parav Pandit]

Currently specification uses virtqueue index and
number interchangeably to refer to the virtqueue.

Instead refer to it by its number.

This patch is on top of [1].

[1] https://lists.oasis-open.org/archives/virtio-dev/202302/msg00527.html

Fixes: https://github.com/oasis-tcs/virtio-spec/issues/163
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Parav Pandit <parav@nvidia.com>
---
changelog:
v2->v3:
- addressed comments from Michael
- changed vqn to virtqueue number in the Note
- refer to vqn field instead of virtqueue number
---
 transport-pci.tex | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/transport-pci.tex b/transport-pci.tex
index b07a822..044c085 100644
--- a/transport-pci.tex
+++ b/transport-pci.tex
@@ -390,13 +390,15 @@ \subsubsection{Common configuration structure layout}\label{sec:Virtio Transport
 
 \item[\field{queue_notify_data}]
         This field exists only if VIRTIO_F_NOTIF_CONFIG_DATA has been negotiated.
-        The driver will use this value to put it in the 'virtqueue number' field
-        in the available buffer notification structure.
+        The driver will use this value to put it in the field
+        \field{vqn} in the available buffer notification
+        structure.
         See section \ref{sec:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Available Buffer Notifications}.
         \begin{note}
         This field provides the device with flexibility to determine how virtqueues
         will be referred to in available buffer notifications.
-        In a trivial case the device can set \field{queue_notify_data}=vqn. Some devices
+        In a trivial case the device can set
+        \field{queue_notify_data}=vq number. Some devices
         may benefit from providing another value, for example an internal virtqueue
         identifier, or an internal offset related to the virtqueue number.
         \end{note}
@@ -1005,7 +1007,7 @@ \subsubsection{Device Initialization}\label{sec:Virtio Transport Options / Virti
 The driver typically does this as follows, for each virtqueue a device has:
 
 \begin{enumerate}
-\item Write the virtqueue index (first queue is 0) to \field{queue_select}.
+\item Write the virtqueue number (first queue is 0) to \field{queue_select}.
 
 \item Read the virtqueue size from \field{queue_size}. This controls how big the virtqueue is
   (see \ref{sec:Basic Facilities of a Virtio Device / Virtqueues}~\nameref{sec:Basic Facilities of a Virtio Device / Virtqueues}). If this field is 0, the virtqueue does not exist.
@@ -1035,7 +1037,7 @@ \subsubsection{Available Buffer Notifications}\label{sec:Virtio Transport Option
 
 When VIRTIO_F_NOTIFICATION_DATA has not been negotiated,
 the driver sends an available buffer notification to the device by writing
-the 16-bit virtqueue index
+the 16-bit virtqueue number
 of this virtqueue to the Queue Notify address.
 
 When VIRTIO_F_NOTIFICATION_DATA has been negotiated,
@@ -1053,7 +1055,7 @@ \subsubsection{Available Buffer Notifications}\label{sec:Virtio Transport Option
 If VIRTIO_F_NOTIF_CONFIG_DATA has been negotiated:
 \begin{itemize}
 \item If VIRTIO_F_NOTIFICATION_DATA has not been negotiated, the driver MUST use the
-\field{queue_notify_data} value instead of the virtqueue index.
+\field{queue_notify_data} value instead of the virtqueue number.
 \item If VIRTIO_F_NOTIFICATION_DATA has been negotiated, the driver MUST set the
 \field{vqn} field to the \field{queue_notify_data} value.
 \end{itemize}
-- 
2.26.2


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[virtio-dev] [PATCH v6 3/8] transport-mmio: Rename QueueNum register

[Parav Pandit]

Currently specification uses virtqueue index and number
interchangeably to refer to the virtqueue.

It is better to always refer to it the virtqueue in consistent manner.

Two registers QueueNumMax and QueueNum actually reflects the queue size
or queue depth indicating max and actual number of entries in the queue.

These are further named differently between pci and mmio transport.
PCI transport indicates queue size as queue_size.

To bring consistency between pci and mmio transport, and to avoid
confusion between number and index, rename the QueueNumMax and QueueNum
registers to QueueSizeMax and QueueSize respectively.

Fixes: https://github.com/oasis-tcs/virtio-spec/issues/163
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Parav Pandit <parav@nvidia.com>

---
changelog:
v0->v1:
- replaced references of QueueNumMax to QueueSizeMax
- replaced references of QueueNum to QueueSize
- added note for renamed fields old name suggested by @Michael Tsirkin
---
 transport-mmio.tex | 42 ++++++++++++++++++++++++++++--------------
 1 file changed, 28 insertions(+), 14 deletions(-)

diff --git a/transport-mmio.tex b/transport-mmio.tex
index f884a2c..3047633 100644
--- a/transport-mmio.tex
+++ b/transport-mmio.tex
@@ -110,24 +110,31 @@ \subsection{MMIO Device Register Layout}\label{sec:Virtio Transport Options / Vi
   \hline
   \mmioreg{QueueSel}{Virtual queue index}{0x030}{W}{%
     Writing to this register selects the virtual queue that the
-    following operations on \field{QueueNumMax}, \field{QueueNum}, \field{QueueReady},
+    following operations on \field{QueueSizeMax},
+    \field{QueueSize}, \field{QueueReady},
     \field{QueueDescLow}, \field{QueueDescHigh}, \field{QueueDriverlLow}, \field{QueueDriverHigh},
     \field{QueueDeviceLow}, \field{QueueDeviceHigh} and \field{QueueReset} apply to. The index
     number of the first queue is zero (0x0).
   }
   \hline
-  \mmioreg{QueueNumMax}{Maximum virtual queue size}{0x034}{R}{%
+  \mmioreg{QueueSizeMax}{Maximum virtual queue size}{0x034}{R}{%
     Reading from the register returns the maximum size (number of
     elements) of the queue the device is ready to process or
     zero (0x0) if the queue is not available. This applies to the
     queue selected by writing to \field{QueueSel}.
+    \begin{note}
+    \field{QueueSizeMax} was previously known as QueueNumMax.
+    \end{note}
   }
   \hline
-  \mmioreg{QueueNum}{Virtual queue size}{0x038}{W}{%
+  \mmioreg{QueueSize}{Virtual queue size}{0x038}{W}{%
     Queue size is the number of elements in the queue.
     Writing to this register notifies the device what size of the
     queue the driver will use. This applies to the queue selected by
     writing to \field{QueueSel}.
+    \begin{note}
+    \field{QueueSize} was previously known as QueueNum.
+    \end{note}
   }
   \hline
   \mmioreg{QueueReady}{Virtual queue ready bit}{0x044}{RW}{%
@@ -308,11 +315,11 @@ \subsection{MMIO Device Register Layout}\label{sec:Virtio Transport Options / Vi
 
 Before writing to the \field{DriverFeatures} register, the driver MUST write a value to the \field{DriverFeaturesSel} register.
 
-The driver MUST write a value to \field{QueueNum} which is less than
-or equal to the value presented by the device in \field{QueueNumMax}.
+The driver MUST write a value to \field{QueueSize} which is less than
+or equal to the value presented by the device in \field{QueueSizeMax}.
 
 When \field{QueueReady} is not zero, the driver MUST NOT access
-\field{QueueNum}, \field{QueueDescLow}, \field{QueueDescHigh},
+\field{QueueSize}, \field{QueueDescLow}, \field{QueueDescHigh},
 \field{QueueDriverLow}, \field{QueueDriverHigh}, \field{QueueDeviceLow}, \field{QueueDeviceHigh}.
 
 To stop using the queue the driver MUST write zero (0x0) to this
@@ -363,14 +370,14 @@ \subsubsection{Virtqueue Configuration}\label{sec:Virtio Transport Options / Vir
    and expect a returned value of zero (0x0).
 
 \item Read maximum queue size (number of elements) from
-   \field{QueueNumMax}. If the returned value is zero (0x0) the
+   \field{QueueSizeMax}. If the returned value is zero (0x0) the
    queue is not available.
 
 \item Allocate and zero the queue memory, making sure the memory
    is physically contiguous.
 
 \item Notify the device about the queue size by writing the size to
-   \field{QueueNum}.
+   \field{QueueSize}.
 
 \item Write physical addresses of the queue's Descriptor Area,
    Driver Area and Device Area to (respectively) the
@@ -465,25 +472,32 @@ \subsection{Legacy interface}\label{sec:Virtio Transport Options / Virtio Over M
   \hline
   \mmioreg{QueueSel}{Virtual queue index}{0x030}{W}{%
     Writing to this register selects the virtual queue that the
-    following operations on the \field{QueueNumMax}, \field{QueueNum}, \field{QueueAlign}
+    following operations on the \field{QueueSizeMax},
+    \field{QueueSize}, \field{QueueAlign}
     and \field{QueuePFN} registers apply to. The index
     number of the first queue is zero (0x0).
 .
   }
   \hline
-  \mmioreg{QueueNumMax}{Maximum virtual queue size}{0x034}{R}{%
+  \mmioreg{QueueSizeMax}{Maximum virtual queue size}{0x034}{R}{%
     Reading from the register returns the maximum size of the queue
     the device is ready to process or zero (0x0) if the queue is not
     available. This applies to the queue selected by writing to
     \field{QueueSel} and is allowed only when \field{QueuePFN} is set to zero
     (0x0), so when the queue is not actively used.
+    \begin{note}
+    \field{QueueSizeMax} was previously known as QueueNumMax.
+    \end{note}
   }
   \hline
-  \mmioreg{QueueNum}{Virtual queue size}{0x038}{W}{%
+  \mmioreg{QueueSize}{Virtual queue size}{0x038}{W}{%
     Queue size is the number of elements in the queue.
     Writing to this register notifies the device what size of the
     queue the driver will use. This applies to the queue selected by
     writing to \field{QueueSel}.
+    \begin{note}
+    \field{QueueSize} was previously known as QueueNum.
+    \end{note}
   }
   \hline
   \mmioreg{QueueAlign}{Used Ring alignment in the virtual queue}{0x03c}{W}{%
@@ -543,16 +557,16 @@ \subsection{Legacy interface}\label{sec:Virtio Transport Options / Virtio Over M
    expecting a returned value of zero (0x0).
 
 \item Read maximum queue size (number of elements) from
-   \field{QueueNumMax}. If the returned value is zero (0x0) the
+   \field{QueueSizeMax}. If the returned value is zero (0x0) the
    queue is not available.
 
 \item Allocate and zero the queue pages in contiguous virtual
    memory, aligning the Used Ring to an optimal boundary (usually
    page size). The driver should choose a queue size smaller than or
-   equal to \field{QueueNumMax}.
+   equal to \field{QueueSizeMax}.
 
 \item Notify the device about the queue size by writing the size to
-   \field{QueueNum}.
+   \field{QueueSize}.
 
 \item Notify the device about the used alignment by writing its value
    in bytes to \field{QueueAlign}.
-- 
2.26.2


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[virtio-dev] [PATCH v6 4/8] transport-mmio: Refer to the vq by its number

[Parav Pandit]

Currently specification uses virtqueue index and
number interchangeably to refer to the virtqueue.

Instead refer to it by its number.

Fixes: https://github.com/oasis-tcs/virtio-spec/issues/163
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Parav Pandit <parav@nvidia.com>
---
 transport-mmio.tex | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/transport-mmio.tex b/transport-mmio.tex
index 3047633..f9b3a34 100644
--- a/transport-mmio.tex
+++ b/transport-mmio.tex
@@ -108,7 +108,7 @@ \subsection{MMIO Device Register Layout}\label{sec:Virtio Transport Options / Vi
     bits accessible by writing to \field{DriverFeatures}.
   }
   \hline
-  \mmioreg{QueueSel}{Virtual queue index}{0x030}{W}{%
+  \mmioreg{QueueSel}{Virtual queue number}{0x030}{W}{%
     Writing to this register selects the virtual queue that the
     following operations on \field{QueueSizeMax},
     \field{QueueSize}, \field{QueueReady},
@@ -149,7 +149,7 @@ \subsection{MMIO Device Register Layout}\label{sec:Virtio Transport Options / Vi
     there are new buffers to process in a queue.
 
     When VIRTIO_F_NOTIFICATION_DATA has not been negotiated,
-    the value written is the queue index.
+    the value written is the queue number.
 
     When VIRTIO_F_NOTIFICATION_DATA has been negotiated,
     the \field{Notification data} value has the following format:
@@ -363,8 +363,7 @@ \subsubsection{Virtqueue Configuration}\label{sec:Virtio Transport Options / Vir
 The driver will typically initialize the virtual queue in the following way:
 
 \begin{enumerate}
-\item Select the queue writing its index (first queue is 0) to
-   \field{QueueSel}.
+\item Select the queue writing its number to \field{QueueSel}.
 
 \item Check if the queue is not already in use: read \field{QueueReady},
    and expect a returned value of zero (0x0).
@@ -392,7 +391,7 @@ \subsubsection{Available Buffer Notifications}\label{sec:Virtio Transport Option
 
 When VIRTIO_F_NOTIFICATION_DATA has not been negotiated,
 the driver sends an available buffer notification to the device by writing
-the 16-bit virtqueue index
+the 16-bit virtqueue number
 of the queue to be notified to \field{QueueNotify}.
 
 When VIRTIO_F_NOTIFICATION_DATA has been negotiated,
@@ -470,7 +469,7 @@ \subsection{Legacy interface}\label{sec:Virtio Transport Options / Virtio Over M
     (see QueuePFN).
   }
   \hline
-  \mmioreg{QueueSel}{Virtual queue index}{0x030}{W}{%
+  \mmioreg{QueueSel}{Virtual queue number}{0x030}{W}{%
     Writing to this register selects the virtual queue that the
     following operations on the \field{QueueSizeMax},
     \field{QueueSize}, \field{QueueAlign}
@@ -550,8 +549,7 @@ \subsection{Legacy interface}\label{sec:Virtio Transport Options / Virtio Over M
 
 The virtual queue is configured as follows:
 \begin{enumerate}
-\item Select the queue writing its index (first queue is 0) to
-   \field{QueueSel}.
+\item Select the queue writing its number to \field{QueueSel}.
 
 \item Check if the queue is not already in use: read \field{QueuePFN},
    expecting a returned value of zero (0x0).
-- 
2.26.2


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[virtio-dev] [PATCH v6 5/8] transport-ccw: Rename queue depth/size to other transports

[Parav Pandit]

max_num field reflects the maximum queue size/depth. Hence align name of
this field with similar field in PCI and MMIO transport to
max_queue_size.
Similarly rename 'num' to 'size'.

Fixes: https://github.com/oasis-tcs/virtio-spec/issues/163
Signed-off-by: Parav Pandit <parav@nvidia.com>

---
v3->v4:
- moved note to comment
---
 transport-ccw.tex | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/transport-ccw.tex b/transport-ccw.tex
index c492cb9..b4bc83b 100644
--- a/transport-ccw.tex
+++ b/transport-ccw.tex
@@ -237,12 +237,12 @@ \subsubsection{Configuring a Virtqueue}\label{sec:Virtio Transport Options / Vir
 \begin{lstlisting}
 struct vq_config_block {
         be16 index;
-        be16 max_num;
+        be16 max_queue_size; /* Previously named as max_num */
 };
 \end{lstlisting}
 
 The requested number of buffers for queue \field{index} is returned in
-\field{max_num}.
+\field{max_queue_size}.
 
 Afterwards, CCW_CMD_SET_VQ is issued by the driver to inform the
 device about the location used for its queue. The transmitted
@@ -253,7 +253,7 @@ \subsubsection{Configuring a Virtqueue}\label{sec:Virtio Transport Options / Vir
         be64 desc;
         be32 res0;
         be16 index;
-        be16 num;
+        be16 size; /* Previously named as num */
         be64 driver;
         be64 device;
 };
@@ -262,7 +262,8 @@ \subsubsection{Configuring a Virtqueue}\label{sec:Virtio Transport Options / Vir
 \field{desc}, \field{driver} and \field{device} contain the guest
 addresses for the descriptor area,
 available area and used area for queue \field{index}, respectively. The actual
-virtqueue size (number of allocated buffers) is transmitted in \field{num}.
+virtqueue size (number of allocated buffers) is transmitted in
+\field{size}.
 
 \devicenormative{\paragraph}{Configuring a Virtqueue}{Virtio Transport Options / Virtio over channel I/O / Device Initialization / Configuring a Virtqueue}
 
@@ -278,11 +279,12 @@ \subsubsection{Configuring a Virtqueue}\label{sec:Virtio Transport Options / Vir
         be64 queue;
         be32 align;
         be16 index;
-        be16 num;
+        be16 size; /* Previously named as num */
 };
 \end{lstlisting}
 
-\field{queue} contains the guest address for queue \field{index}, \field{num} the number of buffers
+\field{queue} contains the guest address for queue \field{index},
+\field{size} the number of buffers
 and \field{align} the alignment. The queue layout follows \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Layout}~\nameref{sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Layout}.
 
 \subsubsection{Communicating Status Information}\label{sec:Virtio Transport Options / Virtio over channel I/O / Device Initialization / Communicating Status Information}
-- 
2.26.2


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[virtio-dev] [PATCH v6 6/8] transport-ccw: Refer to the vq by its number

[Parav Pandit]

Currently specification uses virtqueue index and
number interchangeably to refer to the virtqueue.

Instead refer to it by its number.

Fixes: https://github.com/oasis-tcs/virtio-spec/issues/163
Signed-off-by: Parav Pandit <parav@nvidia.com>

---
changelog:
v3->v4:
- moved note to comment
v2->v3:
- added comment note for queue_select similar to max_queue_size
v0->v1:
- new patch
---
 transport-ccw.tex | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/transport-ccw.tex b/transport-ccw.tex
index b4bc83b..b405db1 100644
--- a/transport-ccw.tex
+++ b/transport-ccw.tex
@@ -236,12 +236,12 @@ \subsubsection{Configuring a Virtqueue}\label{sec:Virtio Transport Options / Vir
 
 \begin{lstlisting}
 struct vq_config_block {
-        be16 index;
+        be16 queue_select; /* Previously named as index */
         be16 max_queue_size; /* Previously named as max_num */
 };
 \end{lstlisting}
 
-The requested number of buffers for queue \field{index} is returned in
+The requested number of buffers for queue \field{queue_select} is returned in
 \field{max_queue_size}.
 
 Afterwards, CCW_CMD_SET_VQ is issued by the driver to inform the
@@ -252,7 +252,7 @@ \subsubsection{Configuring a Virtqueue}\label{sec:Virtio Transport Options / Vir
 struct vq_info_block {
         be64 desc;
         be32 res0;
-        be16 index;
+        be16 queue_select; /* Previously named as index */
         be16 size; /* Previously named as num */
         be64 driver;
         be64 device;
@@ -261,7 +261,7 @@ \subsubsection{Configuring a Virtqueue}\label{sec:Virtio Transport Options / Vir
 
 \field{desc}, \field{driver} and \field{device} contain the guest
 addresses for the descriptor area,
-available area and used area for queue \field{index}, respectively. The actual
+available area and used area for queue number \field{queue_select}, respectively. The actual
 virtqueue size (number of allocated buffers) is transmitted in
 \field{size}.
 
@@ -278,12 +278,13 @@ \subsubsection{Configuring a Virtqueue}\label{sec:Virtio Transport Options / Vir
 struct vq_info_block_legacy {
         be64 queue;
         be32 align;
-        be16 index;
+        be16 queue_select; /* Previously named as index */
         be16 size; /* Previously named as num */
 };
 \end{lstlisting}
 
-\field{queue} contains the guest address for queue \field{index},
+\field{queue} contains the guest address for queue number
+\field{queue_select},
 \field{size} the number of buffers
 and \field{align} the alignment. The queue layout follows \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Layout}~\nameref{sec:Basic Facilities of a Virtio Device / Virtqueues / Legacy Interfaces: A Note on Virtqueue Layout}.
 
@@ -571,7 +572,7 @@ \subsubsection{Guest->Host Notification}\label{sec:Virtio Transport Options / Vi
 For example:
 \begin{lstlisting}
 info->cookie = do_notify(schid,
-                         virtqueue_get_queue_index(vq),
+                         virtqueue_get_queue_number(vq),
                          info->cookie);
 \end{lstlisting}
 \end{note}
-- 
2.26.2


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[virtio-dev] [PATCH v6 7/8] virtio-net: Avoid duplicate receive queue example

[Parav Pandit]

Receive queue number/index example is duplicate which is already defined
in the Setting RSS parameters section.

Hence, avoid such duplicate example and prepare it for the subsequent
patch to describe using receive queue handle.

Fixes: https://github.com/oasis-tcs/virtio-spec/issues/163
Signed-off-by: Parav Pandit <parav@nvidia.com>
---
 device-types/net/description.tex | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/device-types/net/description.tex b/device-types/net/description.tex
index d7c8b1b..435c1fc 100644
--- a/device-types/net/description.tex
+++ b/device-types/net/description.tex
@@ -1467,8 +1467,8 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
 The device MUST determine the destination queue for a network packet as follows:
 \begin{itemize}
 \item Calculate the hash of the packet as defined in \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets}.
-\item If the device did not calculate the hash for the specific packet, the device directs the packet to the receiveq specified by \field{unclassified_queue} of virtio_net_rss_config structure (value of 0 corresponds to receiveq1).
-\item Apply \field{indirection_table_mask} to the calculated hash and use the result as the index in the indirection table to get 0-based number of destination receiveq (value of 0 corresponds to receiveq1).
+\item If the device did not calculate the hash for the specific packet, the device directs the packet to the receiveq specified by \field{unclassified_queue} of virtio_net_rss_config structure.
+\item Apply \field{indirection_table_mask} to the calculated hash and use the result as the index in the indirection table to get 0-based number of destination receiveq.
 \item If the destination receive queue is being reset (See \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Reset}), the device MUST drop the packet.
 \end{itemize}
 
-- 
2.26.2


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[virtio-dev] [PATCH v6 8/8] virtio-net: Describe RSS using rss rq id

[Parav Pandit]

The content of indirection table and unclassified_queue which are
based on math calculation historically. To better describe this, to
avoid intermixing array index with virtqueue index and to use virtqueue
number

introduce a field rq_handle (receive queue handle) and refer them
to describe unclassified_queue and indirection_table fields.

As part of it, have the example that uses non zero virtqueue
number which helps to have better mapping between receiveX
object with virtqueue number and the actual value in the
indirection table.

Fixes: https://github.com/oasis-tcs/virtio-spec/issues/163
Signed-off-by: Parav Pandit <parav@nvidia.com>

---
changelog:
v4->v5:
- change subject to reflect rss_rq_id
- fixed accidental removal of "unclassifed packets".
- simplfied text around indirection_table mask to use the term
  destination receive virtqueue. This aligns with next line about queue
  reset.
- removed rss_rq_id references as indirection table and
  unclassified_queue data type is self explanatory
v3->v4:
- renamed rq_handle to rss_rq_id
- moved rss_rq_id definition close to its usage in rss_config struct
v2->v3:
- moved rq_handle definition before using it
- removed duplicate example as rq_handle is now described first
v0->v1:
- new patch suggested by Michael Tsirkin
---
 device-types/net/description.tex | 26 +++++++++++++++++++-------
 1 file changed, 19 insertions(+), 7 deletions(-)

diff --git a/device-types/net/description.tex b/device-types/net/description.tex
index 435c1fc..d6dd897 100644
--- a/device-types/net/description.tex
+++ b/device-types/net/description.tex
@@ -1423,11 +1423,16 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
 
 Driver sends a VIRTIO_NET_CTRL_MQ_RSS_CONFIG command using the following format for \field{command-specific-data}:
 \begin{lstlisting}
+struct rss_rq_id {
+   le16 vqn_1_16: 15; /* Bits 1 to 16 of the virtqueue number */
+   le16 reserved: 1; /* Set to zero */
+};
+
 struct virtio_net_rss_config {
     le32 hash_types;
     le16 indirection_table_mask;
-    le16 unclassified_queue;
-    le16 indirection_table[indirection_table_length];
+    struct rss_rq_id unclassified_queue;
+    struct rss_rq_id indirection_table[indirection_table_length];
     le16 max_tx_vq;
     u8 hash_key_length;
     u8 hash_key_data[hash_key_length];
@@ -1442,10 +1447,14 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
 \field{indirection_table} array.
 Number of entries in \field{indirection_table} is (\field{indirection_table_mask} + 1).
 
-Field \field{unclassified_queue} contains the 0-based index of
-the receive virtqueue to place unclassified packets in. Index 0 corresponds to receiveq1.
+\field{rss_rq_id} is a receive virtqueue id. \field{vqn_1_16}
+consists of bits 1 to 16 of virtqueue number. For example,
+\field{vqn_1_16} value of 3 corresponds to virtqueue number 6 maps to receiveq4.
+
+Field \field{unclassified_queue} contains the receive virtqueue
+to place unclassified packets in.
 
-Field \field{indirection_table} contains an array of 0-based indices of receive virtqueues. Index 0 corresponds to receiveq1.
+Field \field{indirection_table} is an array of receive virtqueues.
 
 A driver sets \field{max_tx_vq} to inform a device how many transmit virtqueues it may use (transmitq1\ldots transmitq \field{max_tx_vq}).
 
@@ -1455,7 +1464,8 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
 
 A driver MUST NOT send the VIRTIO_NET_CTRL_MQ_RSS_CONFIG command if the feature VIRTIO_NET_F_RSS has not been negotiated.
 
-A driver MUST fill the \field{indirection_table} array only with indices of enabled queues. Index 0 corresponds to receiveq1.
+A driver MUST fill the \field{indirection_table} array only with
+enabled receive virtqueues.
 
 The number of entries in \field{indirection_table} (\field{indirection_table_mask} + 1) MUST be a power of two.
 
@@ -1468,7 +1478,9 @@ \subsubsection{Control Virtqueue}\label{sec:Device Types / Network Device / Devi
 \begin{itemize}
 \item Calculate the hash of the packet as defined in \ref{sec:Device Types / Network Device / Device Operation / Processing of Incoming Packets / Hash calculation for incoming packets}.
 \item If the device did not calculate the hash for the specific packet, the device directs the packet to the receiveq specified by \field{unclassified_queue} of virtio_net_rss_config structure.
-\item Apply \field{indirection_table_mask} to the calculated hash and use the result as the index in the indirection table to get 0-based number of destination receiveq.
+\item Apply \field{indirection_table_mask} to the calculated hash
+and use the result as the index in the indirection table to get
+the destination receive virtqueue.
 \item If the destination receive queue is being reset (See \ref{sec:Basic Facilities of a Virtio Device / Virtqueues / Virtqueue Reset}), the device MUST drop the packet.
 \end{itemize}
 
-- 
2.26.2


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[virtio-dev] Re: [virtio-comment] [PATCH v6 4/8] transport-mmio: Refer to the vq by its number

[Stefano Garzarella]

On Fri, Mar 24, 2023 at 04:04:28AM +0300, Parav Pandit wrote:
>Currently specification uses virtqueue index and
>number interchangeably to refer to the virtqueue.
>
>Instead refer to it by its number.
>
>Fixes: https://github.com/oasis-tcs/virtio-spec/issues/163
>Reviewed-by: Jiri Pirko <jiri@nvidia.com>
>Signed-off-by: Parav Pandit <parav@nvidia.com>
>---
> transport-mmio.tex | 14 ++++++--------
> 1 file changed, 6 insertions(+), 8 deletions(-)
>
>diff --git a/transport-mmio.tex b/transport-mmio.tex
>index 3047633..f9b3a34 100644
>--- a/transport-mmio.tex
>+++ b/transport-mmio.tex
>@@ -108,7 +108,7 @@ \subsection{MMIO Device Register Layout}\label{sec:Virtio Transport Options / Vi
>     bits accessible by writing to \field{DriverFeatures}.
>   }
>   \hline
>-  \mmioreg{QueueSel}{Virtual queue index}{0x030}{W}{%
>+  \mmioreg{QueueSel}{Virtual queue number}{0x030}{W}{%
>     Writing to this register selects the virtual queue that the
>     following operations on \field{QueueSizeMax},
>     \field{QueueSize}, \field{QueueReady},

Maybe we can also remove `index` from the last sentence in this section.
I mean something like this:

--- a/transport-mmio.tex
+++ b/transport-mmio.tex
@@ -113,8 +113,8 @@ \subsection{MMIO Device Register Layout}\label{sec:Virtio Transport Options / Vi
      following operations on \field{QueueSizeMax},
      \field{QueueSize}, \field{QueueReady},
      \field{QueueDescLow}, \field{QueueDescHigh}, \field{QueueDriverlLow}, \field{QueueDriverHigh},
-    \field{QueueDeviceLow}, \field{QueueDeviceHigh} and \field{QueueReset} apply to. The index
-    number of the first queue is zero (0x0).
+    \field{QueueDeviceLow}, \field{QueueDeviceHigh} and \field{QueueReset} apply to.
+    The number of the first queue is zero (0x0).
    }
    \hline
    \mmioreg{QueueSizeMax}{Maximum virtual queue size}{0x034}{R}{%

Thanks,
Stefano

>@@ -149,7 +149,7 @@ \subsection{MMIO Device Register Layout}\label{sec:Virtio Transport Options / Vi
>     there are new buffers to process in a queue.
>
>     When VIRTIO_F_NOTIFICATION_DATA has not been negotiated,
>-    the value written is the queue index.
>+    the value written is the queue number.
>
>     When VIRTIO_F_NOTIFICATION_DATA has been negotiated,
>     the \field{Notification data} value has the following format:
>@@ -363,8 +363,7 @@ \subsubsection{Virtqueue Configuration}\label{sec:Virtio Transport Options / Vir
> The driver will typically initialize the virtual queue in the following way:
>
> \begin{enumerate}
>-\item Select the queue writing its index (first queue is 0) to
>-   \field{QueueSel}.
>+\item Select the queue writing its number to \field{QueueSel}.
>
> \item Check if the queue is not already in use: read \field{QueueReady},
>    and expect a returned value of zero (0x0).
>@@ -392,7 +391,7 @@ \subsubsection{Available Buffer Notifications}\label{sec:Virtio Transport Option
>
> When VIRTIO_F_NOTIFICATION_DATA has not been negotiated,
> the driver sends an available buffer notification to the device by writing
>-the 16-bit virtqueue index
>+the 16-bit virtqueue number
> of the queue to be notified to \field{QueueNotify}.
>
> When VIRTIO_F_NOTIFICATION_DATA has been negotiated,
>@@ -470,7 +469,7 @@ \subsection{Legacy interface}\label{sec:Virtio Transport Options / Virtio Over M
>     (see QueuePFN).
>   }
>   \hline
>-  \mmioreg{QueueSel}{Virtual queue index}{0x030}{W}{%
>+  \mmioreg{QueueSel}{Virtual queue number}{0x030}{W}{%
>     Writing to this register selects the virtual queue that the
>     following operations on the \field{QueueSizeMax},
>     \field{QueueSize}, \field{QueueAlign}
>@@ -550,8 +549,7 @@ \subsection{Legacy interface}\label{sec:Virtio Transport Options / Virtio Over M
>
> The virtual queue is configured as follows:
> \begin{enumerate}
>-\item Select the queue writing its index (first queue is 0) to
>-   \field{QueueSel}.
>+\item Select the queue writing its number to \field{QueueSel}.
>
> \item Check if the queue is not already in use: read \field{QueuePFN},
>    expecting a returned value of zero (0x0).
>-- 
>2.26.2
>
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[virtio-dev] RE: [virtio-comment] [PATCH v6 4/8] transport-mmio: Refer to the vq by its number

[Parav Pandit]

Hi Stefano,

> From: Stefano Garzarella <sgarzare@redhat.com>
> Sent: Monday, March 27, 2023 6:04 AM

> Maybe we can also remove `index` from the last sentence in this section.
> I mean something like this:
> 
> --- a/transport-mmio.tex
> +++ b/transport-mmio.tex
> @@ -113,8 +113,8 @@ \subsection{MMIO Device Register
> Layout}\label{sec:Virtio Transport Options / Vi
>       following operations on \field{QueueSizeMax},
>       \field{QueueSize}, \field{QueueReady},
>       \field{QueueDescLow}, \field{QueueDescHigh}, \field{QueueDriverlLow},
> \field{QueueDriverHigh},
> -    \field{QueueDeviceLow}, \field{QueueDeviceHigh} and \field{QueueReset}
> apply to. The index
> -    number of the first queue is zero (0x0).
> +    \field{QueueDeviceLow}, \field{QueueDeviceHigh} and \field{QueueReset}
> apply to.
> +    The number of the first queue is zero (0x0).
>     }
>     \hline
>     \mmioreg{QueueSizeMax}{Maximum virtual queue size}{0x034}{R}{%
> 
> Thanks,
> Stefano
>
With Michael suggestion, the first patch describes the vq number range.
I think we can drop this duplicate text from here all together.

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[virtio-dev] Re: [virtio-comment] [PATCH v6 4/8] transport-mmio: Refer to the vq by its number

[Stefano Garzarella]

On Mon, Mar 27, 2023 at 01:41:33PM +0000, Parav Pandit wrote:
>Hi Stefano,
>
>> From: Stefano Garzarella <sgarzare@redhat.com>
>> Sent: Monday, March 27, 2023 6:04 AM
>
>> Maybe we can also remove `index` from the last sentence in this section.
>> I mean something like this:
>>
>> --- a/transport-mmio.tex
>> +++ b/transport-mmio.tex
>> @@ -113,8 +113,8 @@ \subsection{MMIO Device Register
>> Layout}\label{sec:Virtio Transport Options / Vi
>>       following operations on \field{QueueSizeMax},
>>       \field{QueueSize}, \field{QueueReady},
>>       \field{QueueDescLow}, \field{QueueDescHigh}, \field{QueueDriverlLow},
>> \field{QueueDriverHigh},
>> -    \field{QueueDeviceLow}, \field{QueueDeviceHigh} and \field{QueueReset}
>> apply to. The index
>> -    number of the first queue is zero (0x0).
>> +    \field{QueueDeviceLow}, \field{QueueDeviceHigh} and \field{QueueReset}
>> apply to.
>> +    The number of the first queue is zero (0x0).
>>     }
>>     \hline
>>     \mmioreg{QueueSizeMax}{Maximum virtual queue size}{0x034}{R}{%
>>
>> Thanks,
>> Stefano
>>
>With Michael suggestion, the first patch describes the vq number range.

I see.

>I think we can drop this duplicate text from here all together.
>

Yep, I agree on that.

Thanks,
Stefano


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[virtio-dev] RE: [virtio-comment] [PATCH v6 4/8] transport-mmio: Refer to the vq by its number

[Parav Pandit]

> From: Stefano Garzarella <sgarzare@redhat.com>
> Sent: Monday, March 27, 2023 9:59 AM
> >>
> >With Michael suggestion, the first patch describes the vq number range.
> 
> I see.
> 
> >I think we can drop this duplicate text from here all together.
> >
> 
> Yep, I agree on that.

Ok. thanks.
Will send v7 fixing this.

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