virtio — archive

[Michael S. Tsirkin <stefanha@redhat.com>]

On Tue, Mar 07, 2023 at 12:31:51PM +0100, Jiri Pirko wrote: > Fri, Mar 03, 2023 at 09:23:14PM CET, stefanha@redhat.com wrote: > >On Fri, Mar 03, 2023 at 08:18:43AM -0500, Michael S. Tsirkin wrote: > >> On Fri, Mar 03, 2023 at 08:13:37AM -0500, Stefan Hajnoczi wrote: > >> > On Thu, Mar 02, 2023 at 06:57:24PM -0500, Michael S. Tsirkin wrote: > >> > > On Thu, Mar 02, 2023 at 03:10:11PM -0500, Stefan Hajnoczi wrote: > >> > > > On Thu, Mar 02, 2023 at 08:05:02AM -0500, 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. > >> > > > > > >> > > > > Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com> > >> > > > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > >> > > > > --- > >> > > > > admin.tex | 108 +++++++++++++++++++++++++++++++++++++++++++++++ > >> > > > > introduction.tex | 3 ++ > >> > > > > 2 files changed, 111 insertions(+) > >> > > > > > >> > > > > diff --git a/admin.tex b/admin.tex > >> > > > > index 3dc47be..7e28b77 100644 > >> > > > > --- a/admin.tex > >> > > > > +++ b/admin.tex > >> > > > > @@ -46,4 +46,112 @@ \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 > >> > > > > >> > > > I notice that the terminology is simply "the driver". "Owner driver" > >> > > > and "group member driver" might be clearer because there will be two > >> > > > (possibly different) drivers involved. > >> > > > >> > > Hmm I don't really want to repeat owner everywhere. > >> > > I will clarify that in this section simple "driver" and "device" are > >> > > owner, "member device" and "member driver" is always called explicitly. > >> > > >> > Sounds good. > >> > > >> > > > > +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; > >> > > > > + u8 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 & - & Group administration commands \\ > >> > > > > +\hline > >> > > > > +0x8000 - 0xFFFF & - & Reserved \\ > >> > > > > +\hline > >> > > > > +\end{tabular} > >> > > > > >> > > > I thought all commands are "group administration commands" but this > >> > > > table makes it look like they are just a subset (0x0000 - 0x7FFF) of > >> > > > group administration commands, which is a paradox. > >> > > > >> > > Well the rest are reserved, maybe we will have more command types who > >> > > knows. No? > >> > > >> > I see. Does that mean the reserved commands don't need to be in the same > >> > format as struct virtio_admin_cmd? > >> > >> I am not good in predicting future ... > >> > >> > The entire section is called "Group administration commands" but I get > >> > the impression it's talking both about admin virtqueue commands in > >> > general and specifically about group administration commands. > >> > > >> > Is it possible to structure this as follows: > >> > > >> > Admin Commands > >> > ...common stuff... > >> > Group Administration Commands (0x0000-0x7fff) > >> > ...specific to group administration commands... > >> > Reserved (0x8000-0xffff) > >> > >> What if I just write it like this: > >> > >> > >> > > > > +\hline \hline > >> > > > > +0x0000 - 0x7FFF & - & commands using struct virtio_admin_cmd \\ > >> > > > > +\hline > >> > > > > +0x8000 - 0xFFFF & - & Reserved for future commands (possibly using a different structure) \\ > >> > >> > >> will this address the comment? > > > >Yes, thanks. > > What is the reason for having this table? I fail to see it. I think it's more a place-holder table in which follow-up patches add entries. I'll check and see if we can get rid of it. > > > > >Stefan >