On Tue, 11 Apr 2023 22:23:33 +0300 Parav Pandit <[email protected]> wrote:
> Currently queue_notify_data register indicates the device > internal queue notification content. This register is > meaningful only when feature bit VIRTIO_F_NOTIF_CONFIG_DATA is > negotiated. > > However, above register name often get confusing association with > very similar feature bit VIRTIO_F_NOTIFICATION_DATA. > > When VIRTIO_F_NOTIFICATION_DATA feature bit is negotiated, > notification really involves sending additional queue progress > related information (not queue identifier or index). > > Hence > 1. to avoid any misunderstanding and association of > queue_notify_data with similar name VIRTIO_F_NOTIFICATION_DATA, > > and > 2. to reflect that queue_notify_data is the actual device > internal virtqueue identifier/index/data/cookie, > > a. rename queue_notify_data to queue_notify_config_data. > queue_notify_config_data. > > b. rename ambiguous vqn to a union of vq_index and vq_config_data > > c. The driver notification section assumes that queue notification contains > vq index always. CONFIG_DATA feature bit introduction missed to > update the driver notification section. Hence, correct it. > > Signed-off-by: Parav Pandit <[email protected]> > > --- > changelog: > v12->v13: > - replace _id with _config_data > - dropped vq identifier > - dropped the idea of union as description is for config data feature > v11->v12: > - new patch > --- > content.tex | 11 ++++++++--- > notifications-be.c | 2 +- > notifications-le.c | 2 +- > transport-pci.tex | 26 ++++++++++++++++---------- > 4 files changed, 26 insertions(+), 15 deletions(-) > > diff --git a/content.tex b/content.tex > index e79d722..601c069 100644 > --- a/content.tex > +++ b/content.tex > @@ -404,8 +404,12 @@ \section{Driver Notifications} \label{sec:Basic > Facilities of a Virtio Device / > notification to the device. > > When VIRTIO_F_NOTIFICATION_DATA has not been negotiated, > -this notification involves sending the > -virtqueue index to the device (method depending on the transport). > +this notification contains either virtqueue > +index if VIRTIO_F_NOTIF_CONFIG_DATA is not negotiated or device > +supplied virtqueue notification data if > +VIRTIO_F_NOTIF_CONFIG_DATA is negotiated. > + > +A method to supply such virtqueue notification data is transport specific. > > However, some devices benefit from the ability to find out the > amount of available data in the queue without accessing the virtqueue in > memory: > @@ -416,7 +420,8 @@ \section{Driver Notifications} \label{sec:Basic > Facilities of a Virtio Device / > the following information: > > \begin{description} > -\item [vqn] VQ number to be notified. > +\item [vq_index_config_data] either virtqueue index or device supplied > + queue notification config data corresponding to a virtqueue. > \item [next_off] Offset > within the ring where the next available ring entry > will be written. > diff --git a/notifications-be.c b/notifications-be.c > index 5be947e..02f0624 100644 > --- a/notifications-be.c > +++ b/notifications-be.c > @@ -1,5 +1,5 @@ > be32 { > - vqn : 16; > + vq_config_data: 16; /* previously known as vqn */ > next_off : 15; > next_wrap : 1; > }; > diff --git a/notifications-le.c b/notifications-le.c > index fe51267..f73c6a5 100644 > --- a/notifications-le.c > +++ b/notifications-le.c > @@ -1,5 +1,5 @@ > le32 { > - vqn : 16; > + vq_config_data: 16; /* previously known as vqn */ Is this where the union was supposed to go? I.e. something like: union { le16 vq_config_data; le16 vq_index; } vq_index_config_data; (You said in the v12 disussion in MID <ph0pr12mb54812c754ed9063e34e06e1bdc...@ph0pr12mb5481.namprd12.prod.outlook.com> that you are going to change vqn to the union of vq_config_data and vq_index, although vq_notif_config_data might be preferable). Or did you mean to do + vq_index_config_data: 16; /* previously known as vqn */ Of course, this has an impact on the rest of the text... > next_off : 15; > next_wrap : 1; > }; > diff --git a/transport-pci.tex b/transport-pci.tex > index 5d98467..53c8ee6 100644 > --- a/transport-pci.tex > +++ b/transport-pci.tex > @@ -319,7 +319,7 @@ \subsubsection{Common configuration structure > layout}\label{sec:Virtio Transport > le64 queue_desc; /* read-write */ > le64 queue_driver; /* read-write */ > le64 queue_device; /* read-write */ > - le16 queue_notify_data; /* read-only for driver */ > + le16 queue_notify_config_data; /* read-only for driver */ > le16 queue_reset; /* read-write */ > }; > \end{lstlisting} > @@ -388,17 +388,21 @@ \subsubsection{Common configuration structure > layout}\label{sec:Virtio Transport > \item[\field{queue_device}] > The driver writes the physical address of Device Area here. See > section \ref{sec:Basic Facilities of a Virtio Device / Virtqueues}. > > -\item[\field{queue_notify_data}] > +\item[\field{queue_notify_config_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 when driver sends available buffer > + notification to the device. > 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 > - may benefit from providing another value, for example an internal > virtqueue > - identifier, or an internal offset related to the virtqueue number. > + In a trivial case the device can set > \field{queue_notify_config_data} to > + virtqueue index. Some devices may benefit from providing another > value, > + for example an internal virtqueue identifier, or an internal offset > + related to the virtqueue index. > + \end{note} > + \begin{note} > + This field is previously known as queue_notify_data. > \end{note} > > \item[\field{queue_reset}] > @@ -468,7 +472,9 @@ \subsubsection{Common configuration structure > layout}\label{sec:Virtio Transport > > \drivernormative{\paragraph}{Common configuration structure layout}{Virtio > Transport Options / Virtio Over PCI Bus / PCI Device Layout / Common > configuration structure layout} > > -The driver MUST NOT write to \field{device_feature}, \field{num_queues}, > \field{config_generation}, \field{queue_notify_off} or > \field{queue_notify_data}. > +The driver MUST NOT write to \field{device_feature}, \field{num_queues}, > +\field{config_generation}, \field{queue_notify_off} or > +\field{queue_notify_config_data}. > > If VIRTIO_F_RING_PACKED has been negotiated, > the driver MUST NOT write the value 0 to \field{queue_size}. > @@ -1053,9 +1059,9 @@ \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_id} value instead of the virtqueue index. > \item If VIRTIO_F_NOTIFICATION_DATA has been negotiated, the driver MUST set > the > -\field{vqn} field to the \field{queue_notify_data} value. > +\field{vq_notify_id} field to the \field{queue_notify_id} value. Seems you did not catch these with the s/_id/_config_data/. By doing the replace one would get queue_notify_config_data, vq_notify_config_data and queue_notify_config_data respectively. But that still does not seem right, and the right answer depends on to what do we rename \field{vqn}. Regards, Halil > \end{itemize} > > \subsubsection{Used Buffer Notifications}\label{sec:Virtio Transport Options > / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / > Used Buffer Notifications} --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
