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 <>
>
> Reviewed-by: Stefan Hajnoczi <>
>
> Reviewed-by: Zhu Lingshan <>
> > ---
> >
>
> 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}\\
