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Subject: Re: [PATCH v12 03/10] admin: introduce group administration commands
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 <mst@redhat.com> > > Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> > > Reviewed-by: Zhu Lingshan <lingshan.zhu@intel.com> > > --- > > > > 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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