On Tue, Apr 25, 2023 at 12:29:02AM +0300, Max Gurtovoy wrote:
>
>
> On 24/04/2023 19:44, Michael S. Tsirkin wrote:
> > This introduces a general structure for group administration commands,
> > used to control device groups through their owner.
> >
> > Following patches will introduce specific commands and an interface for
> > submitting these commands to the owner.
> >
> > Note that the commands are focused on controlling device groups:
> > this is why group related fields are in the generic part of
> > the structure.
> > Without this the admin vq would become a "whatever" vq which does not do
> > anything specific at all, just a general transport like thing.
> > I feel going this way opens the design space to the point where
> > we no longer know what belongs in e.g. config space
> > what in the control q and what in the admin q.
> > As it is, whatever deals with groups is in the admin q; other
> > things not in the admin q.
> >
> > There are specific exceptions such as query but that's an exception that
> > proves the rule ;)
> >
> > Signed-off-by: Michael S. Tsirkin <[email protected]>
> > Reviewed-by: Stefan Hajnoczi <[email protected]>
> > Reviewed-by: Zhu Lingshan <[email protected]>
> > ---
> >
> > changes since v11:
> > acks by Stefan and Lingshan
> >
> > changes since v10:
> > explain the role of status vs status_qualifier, addresses
> > multiple comments
> > add more status values and appropriate qualifiers,
> > as suggested by Parav
> > clarify reserved command opcodes as suggested by Stefan
> > better formatting for ranges, comment by Jiri
> > make sure command-specific-data is a multiple of qword,
> > so things are aligned, suggested by Jiri
> > add Q_OK qualifier for success
> > ---
> > admin.tex | 121 +++++++++++++++++++++++++++++++++++++++++++++++
> > introduction.tex | 3 ++
> > 2 files changed, 124 insertions(+)
> >
> > diff --git a/admin.tex b/admin.tex
> > index 05d506a..d6042e4 100644
> > --- a/admin.tex
> > +++ b/admin.tex
> > @@ -60,4 +60,125 @@ \section{Device groups}\label{sec:Basic Facilities of a
> > Virtio Device / Device g
> > PCI transport (see \ref{sec:Virtio Transport Options / Virtio Over PCI
> > Bus}).
> > \end{description}
> > +\subsection{Group administration commands}\label{sec:Basic Facilities of a
> > Virtio Device / Device groups / Group administration commands}
> > +The driver sends group administration commands to the owner device of
> > +a group to control member devices of the group.
> > +This mechanism can
> > +be used, for example, to configure a member device before it is
> > +initialized by its driver.
> > +\footnote{The term "administration" is intended to be interpreted
> > +widely to include any kind of control. See specific commands
> > +for detail.}
> > +
> > +All the group administration commands are of the following form:
> > +
> > +\begin{lstlisting}
> > +struct virtio_admin_cmd {
> > + /* Device-readable part */
> > + le16 opcode;
> > + /*
> > + * 1 - SR-IOV
> > + * 2-65535 - reserved
> > + */
> > + le16 group_type;
> > + /* unused, reserved for future extensions */
> > + u8 reserved1[12];
> > + le64 group_member_id;
> > + le64 command_specific_data[];
> > +
> > + /* Device-writable part */
> > + le16 status;
> > + le16 status_qualifier;
> > + /* unused, reserved for future extensions */
> > + u8 reserved2[4];
> > + u8 command_specific_result[];
> > +};
> > +\end{lstlisting}
> > +
> > +For all commands, \field{opcode}, \field{group_type} and if
> > +necessary \field{group_member_id} and \field{command_specific_data} are
> > +set by the driver, and the owner device sets \field{status} and if
> > +needed \field{status_qualifier} and
> > +\field{command_specific_result}.
> > +
> > +Generally, any unused device-readable fields are set to zero by the driver
> > +and ignored by the device. Any unused device-writeable fields are set to
> > zero
> > +by the device and ignored by the driver.
> > +
> > +\field{opcode} specifies the command. The valid
> > +values for \field{opcode} can be found in the following table:
> > +
> > +\begin{tabular}{|l|l|}
> > +\hline
> > +opcode & Name & Command Description \\
> > +\hline \hline
> > +0x0000 - 0x7FFF & - & Commands using \field{struct virtio_admin_cmd} \\
> > +\hline
> > +0x8000 - 0xFFFF & - & Reserved for future commands (possibly using a
> > different structure) \\
> > +\hline
> > +\end{tabular}
> > +
> > +The \field{group_type} specifies the group type identifier.
> > +The \field{group_member_id} specifies the member identifier within the
> > group.
> > +See section \ref{sec:Introduction / Terminology / Device group}
> > +for the definition of the group type identifier and group member
> > +identifier.
> > +
> > +The \field{status} describes the command result and possibly
> > +failure reason at an abstract level, this is appropriate for
> > +forwarding to applications. The \field{status_qualifier} describes
> > +failures at a low virtio specific level, as appropriate for debugging.
> > +The following table describes possible \field{status} values;
> > +to simplify common implementations, they are intentionally
> > +matching common \hyperref[intro:errno]{Linux error names and numbers}:
> > +
> > +\begin{tabular}{|l|l|l|}
> > +\hline
> > +Status (decimal) & Name & Description \\
> > +\hline \hline
> > +00 & VIRTIO_ADMIN_STATUS_OK & successful completion \\
> > +\hline
> > +11 & VIRTIO_ADMIN_STATUS_EAGAIN & try again \\
> > +\hline
> > +12 & VIRTIO_ADMIN_STATUS_ENOMEM & insufficient resources \\
> > +\hline
> > +22 & VIRTIO_ADMIN_STATUS_EINVAL & invalid command \\
> > +\hline
> > +other & - & group administration command error \\
> > +\hline
> > +\end{tabular}
> > +
> > +When \field{status} is VIRTIO_ADMIN_STATUS_OK, \field{status_qualifier}
> > +is reserved and set to zero by the device.
> > +
>
> actually it is:
>
> When \field{status} is VIRTIO_ADMIN_STATUS_OK, \field{status_qualifier}
> can be ignored by driver and set to VIRTIO_ADMIN_STATUS_Q_OK by the device.
ok though it's mostly the same, VIRTIO_ADMIN_STATUS_Q_OK is 0 ...
> Can be moved after the status_qualifier values paragraph.
>
>
> > +The following table describes possible \field{status_qualifier} values:
> > +\begin{tabular}{|l|l|l|}
> > +\hline
> > +Status & Name & Description \\
> > +\hline \hline
> > +0x00 & VIRTIO_ADMIN_STATUS_Q_OK & used with
> > VIRTIO_ADMIN_STATUS_OK \\
> > +\hline
> > +0x01 & VIRTIO_ADMIN_STATUS_Q_INVALID_COMMAND & command error: no
> > additional information \\
> > +\hline
> > +0x02 & VIRTIO_ADMIN_STATUS_Q_INVALID_OPCODE & unsupported or invalid
> > \field{opcode} \\
> > +\hline
> > +0x03 & VIRTIO_ADMIN_STATUS_Q_INVALID_FIELD & unsupported or invalid
> > field within \field{command_specific_data} \\
> > +\hline
> > +0x04 & VIRTIO_ADMIN_STATUS_Q_INVALID_GROUP & unsupported or invalid
> > \field{group_type} \\
> > +\hline
> > +0x05 & VIRTIO_ADMIN_STATUS_Q_INVALID_MEMBER & unsupported or invalid
> > \field{group_member_id} \\
> > +\hline
> > +0x06 & VIRTIO_ADMIN_STATUS_Q_NORESOURCE & out of internal
> > resources: ok to retry \\
> > +\hline
> > +0x07 & VIRTIO_ADMIN_STATUS_Q_TRYAGAIN & command blocks for too
> > long: should retry \\
> > +\hline
> > +0x08-0xFFFF & - & reserved for future use \\
> > +\hline
> > +\end{tabular}
>
> should we mention which status_qualifier can match to which status (as we
> did for STATUS_OK) ?
conformance clauses do this.
> > +
> > +Each command uses a different \field{command_specific_data} and
> > +\field{command_specific_result} structures and the length of
> > +\field{command_specific_data} and \field{command_specific_result}
> > +depends on these structures and is described separately or is
> > +implicit in the structure description.
> > diff --git a/introduction.tex b/introduction.tex
> > index 287c5fc..b7155bf 100644
> > --- a/introduction.tex
> > +++ b/introduction.tex
> > @@ -68,6 +68,9 @@ \section{Normative References}\label{sec:Normative
> > References}
> > \phantomsection\label{intro:FUSE}\textbf{[FUSE]} &
> > Linux FUSE interface,
> >
> > \newline\url{https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/fuse.h}\\
> > + \phantomsection\label{intro:errno}\textbf{[errno]} &
> > + Linux error names and numbers,
> > +
> > \newline\url{https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/uapi/asm-generic/errno-base.h}\\
> > \phantomsection\label{intro:eMMC}\textbf{[eMMC]} &
> > eMMC Electrical Standard (5.1), JESD84-B51,
> >
> > \newline\url{http://www.jedec.org/sites/default/files/docs/JESD84-B51.pdf}\\
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