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

["Zhu, Lingshan" <lingshan.zhu@intel.com>]

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!
>
> 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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