Re: [PATCH v1 2/2] transport-pci: Add legacy register access conformance section

["Michael S. Tsirkin" <mst@redhat.com>]

On Wed, May 03, 2023 at 06:26:59AM +0300, Parav Pandit wrote:
> Add device and driver conformanace section for legacy registers access
> commands interface.
> 
> Fixes: https://github.com/oasis-tcs/virtio-spec/issues/167
> Signed-off-by: Parav Pandit <parav@nvidia.com>
> ---
>  conformance.tex           |  2 ++
>  transport-pci-vf-regs.tex | 31 +++++++++++++++++++++++++++++++
>  2 files changed, 33 insertions(+)
> 
> diff --git a/conformance.tex b/conformance.tex
> index 01ccd69..dbd8cd6 100644
> --- a/conformance.tex
> +++ b/conformance.tex
> @@ -109,6 +109,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets}
>  \item \ref{drivernormative:Virtio Transport Options / Virtio Over PCI Bus / PCI Device Layout / PCI configuration access capability}
>  \item \ref{drivernormative:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / MSI-X Vector Configuration}
>  \item \ref{drivernormative:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Notification of Device Configuration Changes}
> +\item \ref{drivernormative:Virtio Transport Options / Virtio Over PCI Bus / SR-IOV Legacy Registers Access}
>  \end{itemize}
>  
>  \conformance{\subsection}{MMIO Driver Conformance}\label{sec:Conformance / Driver Conformance / MMIO Driver Conformance}
> @@ -194,6 +195,7 @@ \section{Conformance Targets}\label{sec:Conformance / Conformance Targets}
>  \item \ref{devicenormative:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Device Initialization / MSI-X Vector Configuration}
>  \item \ref{devicenormative:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Used Buffer Notifications}
>  \item \ref{devicenormative:Virtio Transport Options / Virtio Over PCI Bus / PCI-specific Initialization And Device Operation / Notification of Device Configuration Changes}
> +\item \ref{devicenormative:Virtio Transport Options / Virtio Over PCI Bus / SR-IOV Legacy Registers Access}
>  \end{itemize}
>  
>  \conformance{\subsection}{MMIO Device Conformance}\label{sec:Conformance / Device Conformance / MMIO Device Conformance}
> diff --git a/transport-pci-vf-regs.tex b/transport-pci-vf-regs.tex
> index 16ced32..7d0574b 100644
> --- a/transport-pci-vf-regs.tex
> +++ b/transport-pci-vf-regs.tex
> @@ -82,3 +82,34 @@ \subsubsection{Legacy Queue Notify Offset Query}\label{sec:Virtio Transport Opti
>  	le64 offset; /* Byte offset within the BAR */
>  };
>  \end{lstlisting}
> +
> +\devicenormative{\paragraph}{SR-IOV VFs Legacy Registers Access}{Virtio Transport Options / Virtio Over PCI Bus / SR-IOV Legacy Registers Access}
> +
> +If the PCI PF device supports legacy registers access, it SHOULD set
> +corresponding bits for commands VIRTIO_ADMIN_CMD_LREG_WRITE,
> +VIRTIO_ADMIN_CMD_LREG_READ and VIRTIO_ADMIN_CMD_LQ_NOTIFY_QUERY in 
> +command result of VIRTIO_ADMIN_CMD_LIST_QUERY in
> +\field{device_admin_cmd_opcodes}.

Don't repeat documentation of VIRTIO_ADMIN_CMD_LIST_QUERY please.
just say all these must be supported.
In fact what are you saying here? That all 3 are supported
or none at all? What about just
VIRTIO_ADMIN_CMD_LREG_READ/VIRTIO_ADMIN_CMD_LREG_WRITE?
Looks like a slower but working way to do notifications
is through a common config write, no?

> +
> +The device MUST support legacy configuration registers to its defined width.

what is this?

> +
> +The device MAY fail legacy configuration registers access when either the 
> +access is for an incorrct register width or if the register offset is incorrect.

with which error code?

> +
> +The device MUST allow access of one or multiple bytes of the registers when
> +such register is defined as byte array, for example \field{mac} of \field{struct
> +virtio_net_config} of the Network Device.

so which accesses need to be supported then?

> +
> +\drivernormative{\paragraph}{SR-IOV VFs Legacy Registers Access}{Virtio Transport Options / Virtio Over PCI Bus / SR-IOV Legacy Registers Access}
> +
> +The driver MUST access legacy configuration registers to its defined width.
> +
> +The driver MUST access device specific registers to its defined width
> +
> +The driver MAY access one or multiple bytes of the device specific registers
> +which are defined as byte array, for example \field{mac} of \field{struct
> +virtio_net_config} of the Network Device.
> +
> +The driver SHOULD access all the bytes of a device specific registers in a
> +single access when accessing a byte array, for example \field{mac} of
> +\field{struct virtio_net_config} of the Network Device.
> -- 
> 2.26.2