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Subject: Re: [PATCH RFC v7 2/8] Introduce group administration commands
On Sat, Aug 13, 2022 at 1:19 AM Michael S. Tsirkin <mst@redhat.com> wrote: > > From: Max Gurtovoy <mgurtovoy@nvidia.com> > > These commands are used for essential administrative and management > operations. > > Following patches will introduce an interface for submitting these > commands to the device. > > Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com> > --- > admin.tex | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++++--- > 1 file changed, 94 insertions(+), 5 deletions(-) > > diff --git a/admin.tex b/admin.tex > index 6e9434a..4840dd4 100644 > --- a/admin.tex > +++ b/admin.tex > @@ -9,8 +9,10 @@ \section{Device groups}\label{sec:Basic Facilities of a Virtio Device / Device g > \item[Parent device] > or parent, the device controlling the group. > \item[Member device] > - a device within a group. Parent device itself may, or may > - not be a member of the group. > + a device within a group. Parent device itself is not > + a member of the group. In the future it is envisoned that > + new group types may be introduced where the parent > + device is a member of the group. This part should go with patch 1? > \item[Member identifier] > each member has this indentifier, unique within the group > and used to address it through the parent device. > @@ -20,9 +22,10 @@ \section{Device groups}\label{sec:Basic Facilities of a Virtio Device / Device g > and what kind of control does the parent have. > \item[Group identifier] > each group has this identifier, unique within the parent device. > - this specifies the group type and possibly selects the > - group if multiple groups of the same type can be controlled by the same > - parent device. > + This specifies the group type. In the future it is > + envisoned that new group types will be introduced where the group > + identifier also selects the group if multiple groups of the same > + type can be controlled by the same parent device. > \end{description} > > A single group type is currently specified: > @@ -46,4 +49,90 @@ \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 / Group administration commands} > + > +Group administration commands can be issued through a parent > +device to control member devices of a group. This mechanism can > +be used, for example, to configure a member device before it is > +initialized by its driver. > + > +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_id; I wonder about the implication of this field. Does it mean: 1) a single admin virtqueue that manage two group of VFs or 2) a single admin virtqueue that manages both VFs and SFs (then 'group_type' should be better?) If it's 1, the group id seems not sufficient. If it's 2, I wonder if it scales (using a single admin virtqueue to manage both VF and SF). Thanks > + /* unused, reserved for future extensions */ > + u8 reserved1[12]; > + le64 group_member_id; > + u8 command_specific_data[]; > + > + /* Device-writable part */ > + u8 status; > + u8 command_specific_error; > + /* unused, reserved for future extensions */ > + u8 reserved2[6]; > + u8 command_specific_result[]; > +}; > +\end{lstlisting} > + > +For all commands, \field{opcode}, \field{group_id} and if > +necessary \field{group_member_id} and \field{command_specific_data} are > +set by the driver, and the parent device sets \field{status} and if > +needed \field{command_specific_error} and > +\field{command_specific_result}. > + > +As a rule, 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 & Command Description \\ > +\hline \hline > +0000h - 7FFFh & Group administration commands \\ > +\hline > +8000h - FFFFh & Reserved \\ > +\hline > +\end{tabular} > + > +The \field{group_id} specifies the device group. > +The \field{group_member_id} specifies the member device within the group. > +See section \ref{sec:Introduction / Terminology / Device group} > +for the definition of the group identifier and group member > +identifier. > + > +The following table describes possible \field{status} values: > + > +\begin{tabular}{|l|l|l|} > +\hline > +Status & Name & Description \\ > +\hline \hline > +00h & VIRTIO_ADMIN_STATUS_OK & successful completion \\ > +\hline > +01h & VIRTIO_ADMIN_STATUS_CS_ERR & command specific error \\ > +\hline > +02h & VIRTIO_ADMIN_STATUS_OPCODE_UNSUPPORTED & unsupported or invalid \field{opcode} \\ > +\hline > +03h & VIRTIO_ADMIN_STATUS_INVALID_FIELD & invalid field within command specific data \\ > +\hline > +04h & VIRTIO_ADMIN_STATUS_INVALID_GROUP & invalid group identifier was set \\ > +\hline > +05h & VIRTIO_ADMIN_STATUS_INVALID_MEM & invalid group member identifier was set \\ > +\hline > +\end{tabular} > + > +The \field{command_specific_error} should be inspected by the driver only if \field{status} is set to > +VIRTIO_ADMIN_STATUS_CS_ERR by the device. In this case, the > +contents of \field{command_specific_error} > +holds the command specific error. If \field{status} is not set to VIRTIO_ADMIN_STATUS_CS_ERR, the > +\field{command_specific_error} value is undefined and should be ignored by the driver. > > -- > MST >
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