Re: [virtio-dev] Re: [PATCH RFC v7 8/8] admin command list discovery

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Aug 18, 2022 at 04:56:43PM +0800, Zhu, Lingshan wrote:
> 
> 
> On 8/18/2022 4:51 PM, Jason Wang wrote:
> > On Sat, Aug 13, 2022 at 1:19 AM Michael S. Tsirkin <mst@redhat.com> wrote:
> > > From: Max Gurtovoy <mgurtovoy@nvidia.com>
> > > 
> > > Add commands to find out which commands does each group support.
> > > This will be useful once we have multiple group types.
> > I still wonder if it's better to just use different types of
> > virtqueues, it seems more simple than this.
> Agree!

Not sure what you are agreeing to.

But I'm not sure about this command anyway, I think I will just drop it.


> > 
> > Thanks
> > 
> > > Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com>
> > > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > > ---
> > >   admin.tex | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++++--
> > >   1 file changed, 70 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/admin.tex b/admin.tex
> > > index 99b6c2a..5956c48 100644
> > > --- a/admin.tex
> > > +++ b/admin.tex
> > > @@ -96,9 +96,11 @@ \subsection{Group administration commands}\label{sec:Basic Facilities of a Virti
> > > 
> > >   \begin{tabular}{|l|l|}
> > >   \hline
> > > -opcode & Command Description \\
> > > +opcode & Name & Command Description \\
> > >   \hline \hline
> > > -0000h - 7FFFh   & Group administration commands    \\
> > > +0000h & VIRTIO_ADMIN_CMD_LIST_QUERY & Provides to driver list of commands supported for this group type    \\
> > > +0001h & VIRTIO_ADMIN_CMD_LIST_ACCEPT & Provides to device list of commands used for this group type \\
> > > +0002h - 7FFFh & - &  Group administration commands    \\
> > >   \hline
> > >   8000h - FFFFh   & Reserved    \\
> > >   \hline
> > > @@ -142,6 +144,72 @@ \subsection{Group administration commands}\label{sec:Basic Facilities of a Virti
> > >   structures to the shorter of the two (submitted by driver and
> > >   described in this specification).
> > > 
> > > +Before sending any other commands for any member of a specific
> > > +group to the device, the driver issues the commands
> > > +VIRTIO_ADMIN_CMD_LIST_QUERY and VIRTIO_ADMIN_CMD_LIST_ACCEPT.
> > > +
> > > +
> > > +Commands VIRTIO_ADMIN_CMD_LIST_QUERY and VIRTIO_ADMIN_CMD_LIST_ACCEPT
> > > +both use the following structure describing the
> > > +command opcodes:
> > > +
> > > +\begin{lstlisting}
> > > +struct virtio_admin_cmd_list {
> > > +       /* Indicates which of the below fields were returned
> > > +       le32 device_admin_cmds[];
> > > +};
> > > +\end{lstlisting}
> > > +
> > > +This structure is an array of 32 bit values in little-endian byte
> > > +order, in which a bit is set if the specific command opcode
> > > +is supported. For example, the array of size 2 including
> > > +the values 0x3 and 0x1 indicates that only opcodes 0, 1 and 32
> > > +are supported.
> > > +
> > > +Accordingly, bits 0 and 1 corresponding to opcode 0
> > > +(VIRTIO_ADMIN_CMD_LIST_QUERY) and 1 (VIRTIO_ADMIN_CMD_LIST_ACCEPT) must
> > > +always be set in \field{device_admin_cmds}.
> > > +
> > > +
> > > +For the command VIRTIO_ADMIN_CMD_LIST_QUERY, \field{opcode} is set to 0x0.
> > > +The \field{group_member_id} is unused. It must be set to zero by driver.
> > > +This command has no command specific data.
> > > +The device, upon success, returns a result in the format
> > > +\field{struct virtio_admin_cmd_list} describing the
> > > +list of administration commands supported for the given group.
> > > +
> > > +
> > > +For the command VIRTIO_ADMIN_CMD_LIST_ACCEPT, \field{opcode}
> > > +is set to 0x1.
> > > +The \field{group_member_id} is unused. It must be set to zero by driver.
> > > +The command specific data is in the format
> > > +\field{struct virtio_admin_cmd_list} describing the
> > > +list of administration commands used by the driver.
> > > +This command has no command specific result.
> > > +
> > > +The driver issues the command VIRTIO_ADMIN_CMD_LIST_QUERY to
> > > +query the list of commands valid for this group.  before sending
> > > +any commands for any member of a group.
> > > +
> > > +The driver then accepts some of the opcodes by sending to
> > > +the device the command VIRTIO_ADMIN_CMD_LIST_ACCEPT with a subset
> > > +of the list returned by VIRTIO_ADMIN_CMD_LIST_QUERY that is
> > > +both understood and used by the driver.
> > > +
> > > +If the device supports the command list used by the driver, the
> > > +device completes the command with status VIRTIO_ADMIN_STATUS_OK.
> > > +If the device does not support the command list, the device
> > > +completes the command with status
> > > +VIRTIO_ADMIN_STATUS_INVALID_FIELD.
> > > +
> > > +Note: drivers SHOULD NOT set bits in device_admin_cmds
> > > +if they are not familiar with how the command opcode
> > > +is used, since devices MAY have dependencies between
> > > +command opcodes.
> > > +
> > > +It is assumed that all members in a group support and are used
> > > +with the same list of commands.
> > > +
> > >   \section{Administration Virtqueue}\label{sec:Basic Facilities of a Virtio Device / Group Administration Virtqueues}
> > > 
> > >   An administration virtqueue of a parent device is used to submit
> > > --
> > > MST
> > > 
> > 
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