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Subject: Re: [PATCH v10 09/10] admin: conformance clauses
On 3/2/2023 9:05 PM, Michael S. Tsirkin wrote:
Add conformance clauses for admin commands and admin virtqueues. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- admin.tex | 216 +++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 215 insertions(+), 1 deletion(-) diff --git a/admin.tex b/admin.tex index 1172054..6c4f79c 100644 --- a/admin.tex +++ b/admin.tex @@ -251,6 +251,145 @@ \subsection{Group administration commands}\label{sec:Basic Facilities of a Virti supporting multiple group types, the list of supported commands might differ between different group types.+\devicenormative{\paragraph}{Group administration commands}{Basic Facilities of a Virtio Device / Device groups / Group administration commands}+ +The device MUST validate \field{opcode}, \field{group_type} and +\field{group_member_id}, and if any of these has an invalid or +unsupported value, set \field{status} to +VIRTIO_ADMIN_STATUS_EINVAL and set \field{status_qualifier} +accordingly: +\begin{itemize} +\item if \field{group_type} is invalid, \field{status_qualifier} + MUST be set to VIRTIO_ADMIN_STATUS_Q_INVALID_GROUP; +\item otherwise, if \field{opcode} is invalid, + \field{status_qualifier} MUST be set to + VIRTIO_ADMIN_STATUS_Q_INVALID_OPCODE; +\item otherwise, if \field{group_member_id} is used by the + specific command and is invalid, \field{status_qualifier} MUST be + set to VIRTIO_ADMIN_STATUS_Q_INVALID_MEMBER. +\end{itemize} + +If a command completes successfully, the device MUST set +\field{status} to VIRTIO_ADMIN_STATUS_OK. + +If a command fails, the device MUST set +\field{status} to a value different from VIRTIO_ADMIN_STATUS_OK. + +If \field{status} is set to VIRTIO_ADMIN_STATUS_EINVAL, the +device state MUST NOT change, that is the command MUST NOT have +any side effects on the device, in particular the device MUST not +enter an error state as a result of this command. + +If a command fails, the device state generally SHOULD NOT change, +as far as possible. + +The device MAY enforce additional restrictions and dependencies on +opcodes used by the driver and MAY fail the command +VIRTIO_ADMIN_CMD_LIST_USE with \field{status} set to VIRTIO_ADMIN_STATUS_EINVAL +and \field{status_qualifier} set to VIRTIO_ADMIN_STATUS_Q_INVALID_FIELD +if the list of commands used violate internal device dependencies. + +If the device supports multiple group types, commands for each group +type MUST operate independently of each other, in particular, +the device MAY return different results for VIRTIO_ADMIN_CMD_LIST_QUERY +for different group types. + +After reset, if the device supports a given group type +and before receiving VIRTIO_ADMIN_CMD_LIST_USE for this group type +the device MUST assume +that the list of legal commands used by the driver consists of +the two commands VIRTIO_ADMIN_CMD_LIST_QUERY and VIRTIO_ADMIN_CMD_LIST_USE. + +After completing VIRTIO_ADMIN_CMD_LIST_USE successfully, +the device MUST set the list of legal commands used by the driver +to the one supplied in \field{command_specific_data}. + +The device MUST set the list of legal commands used by the driver +to the one supplied in VIRTIO_ADMIN_CMD_LIST_USE. + +The device MUST validate commands against the list used by +the driver and MUST fail any commands not in the list with +\field{status} set to VIRTIO_ADMIN_STATUS_EINVAL +and \field{status_qualifier} set to +VIRTIO_ADMIN_STATUS_Q_INVALID_OPCODE. + +The list of supported commands MUST NOT shrink (but MAY expand): +after reporting a given command as supported through +VIRTIO_ADMIN_CMD_LIST_QUERY the device MUST NOT later report it +as unsupported. Further, after a given set of commands has been
Can the driver re-negotiate the command list through QUERY/USE in flight rather than upon a reset? If not, shall forbid this explicitly?
+used (via a successful VIRTIO_ADMIN_CMD_LIST_USE), then after a +device or system reset the device SHOULD complete successfully +any following calls to VIRTIO_ADMIN_CMD_LIST_USE with the same +list of commands; if this command VIRTIO_ADMIN_CMD_LIST_USE fails
I think this requires the device to remember what it had offered evenafter a power-cycled reset, shall we say: The device should always offer all supported
commands in the list? Thanks, Zhu Lingshan
+after a device or system reset, the device MUST not fail it +solely because of the command list used. Failure to do so would +interfere with resuming from suspend and error recovery. + +When processing a command with the SR-IOV group type, +if the device does not have an SR-IOV Extended Capability or +if \field{VF Enable} is clear +then the device MUST fail all commands with +\field{status} set to VIRTIO_ADMIN_STATUS_EINVAL and +\field{status_qualifier} set to +VIRTIO_ADMIN_STATUS_Q_INVALID_GROUP; +otherwise, if \field{group_member_id} is not +between $1$ and \field{NumVFs} inclusive, +the device MUST fail all commands with +\field{status} set to VIRTIO_ADMIN_STATUS_EINVAL and +\field{status_qualifier} set to +VIRTIO_ADMIN_STATUS_Q_INVALID_MEMBER; +\field{NumVFs}, \field{VF Migration Capable} and +\field{VF Enable} refer to registers within the SR-IOV Extended +Capability as specified by \hyperref[intro:PCIe]{[PCIe]}. + +\drivernormative{\paragraph}{Group administration commands}{Basic Facilities of a Virtio Device / Device groups / Group administration commands} + +The driver MAY discover whether device supports a specific group type +by issuing VIRTIO_ADMIN_CMD_LIST_QUERY with the matching +\field{group_type}. + +The driver MUST issue VIRTIO_ADMIN_CMD_LIST_USE +and wait for it to be completed with status +VIRTIO_ADMIN_STATUS_OK before issuing any commands +(except for the initial VIRTIO_ADMIN_CMD_LIST_QUERY +and VIRTIO_ADMIN_CMD_LIST_USE). + +The driver SHOULD NOT set bits in device_admin_cmds +if it is not familiar with how the command opcode +is used, as dependencies between command opcodes might exist. + +The driver MUST NOT request (via VIRTIO_ADMIN_CMD_LIST_USE) +the use of any commands not previously reported as +supported for the same group type by VIRTIO_ADMIN_CMD_LIST_QUERY. + +The driver MUST NOT use any commands for a given group type +before sending VIRTIO_ADMIN_CMD_LIST_USE with the correct +list of command opcodes and group type. + +The driver MAY block use of VIRTIO_ADMIN_CMD_LIST_QUERY and +VIRTIO_ADMIN_CMD_LIST_USE by issuing VIRTIO_ADMIN_CMD_LIST_USE +with respective bits cleared in \field{command_specific_data}. + +The driver MUST handle a command error with a reserved \field{status} +value in the same way as \field{status} set to VIRTIO_ADMIN_STATUS_EINVAL +(except possibly for different error reporting/diagnostic messages). + +The driver MUST handle a command error with a reserved +\field{status_qualifier} value in the same way as +\field{status_qualifier} set to +VIRTIO_ADMIN_STATUS_Q_INVALID_COMMAND (except possibly for +different error reporting/diagnostic messages). + +When sending commands with the SR-IOV group type, +the driver specify a value for \field{group_member_id} +between $1$ and \field{NumVFs} inclusive, +the driver MUST also make sure that as long as any such command +is outstanding, \field{VF Migration Capable} is clear and +\field{VF Enable} is set; +\field{NumVFs}, \field{VF Migration Capable} and +\field{VF Enable} refer to registers within the SR-IOV Extended +Capability as specified by \hyperref[intro:PCIe]{[PCIe]}. + \section{Administration Virtqueues}\label{sec:Basic Facilities of a Virtio Device / Administration Virtqueues}An administration virtqueue of an owner device is used to submit@@ -323,4 +462,79 @@ \section{Administration Virtqueues}\label{sec:Basic Facilities of a Virtio Devic of the specification are designed, new fields can be added to the tail of a structure, with the driver/device using the full structure without concern for versioning. ->>>>>>> 0edc690... admin: introduce virtio admin virtqueues + +\devicenormative{\paragraph}{Group administration commands}{Basic Facilities of a Virtio Device / Administration virtqueues} + +The device MUST support device-readable and device-writeable buffers +shorter than described in this specification, by +\begin{enumerate} +\item acting as if any data that would be read outside the +device-readable buffers is set to zero, and +\item discarding data that would be written outside the +specified device-writeable buffers. +\end{enumerate} + +The device MUST support device-readable and device-writeable buffers +longer than described in this specification, by +\begin{enumerate} +\item ignoring any data in device-readable buffers outside +the expected length, and +\item only writing the expected structure to the device-writeable +buffers, ignoring any extra buffers, and reporting the +actual length of data written, in bytes, +as buffer used length. +\end{enumerate} + +The device SHOULD initialize the device-writeable buffer +up to the length of the structure described by this specification or +the length of the buffer supplied by the driver (even if the buffer is +all set to zero), whichever is shorter. + +The device MUST NOT fail a command solely because the buffers +provided are shorter or longer than described in this +specification. + +The device MUST initialize the device-writeable part of +\field{struct virtio_admin_cmd} that is a multiple of 64 bit in +size. + +The device MUST initialize \field{status} in \field{struct +virtio_admin_cmd}. + +The device MUST process commands on a given administration virtqueue +in the order in which they are queued. + +If multiple administration virtqueues have been configured, +device MAY process commands on distinct virtqueues with +no order constraints. + +\drivernormative{\paragraph}{Group administration commands}{Basic Facilities of a Virtio Device / Administration virtqueues} + +The driver MAY supply device-readable or device-writeable parts +of \field{struct virtio_admin_cmd} that are longer than described in +this specification. + +The driver SHOULD supply device-readable part of +\field{struct virtio_admin_cmd} that is at least as +large as the structure described by this specification +(even if the structure is all set to zero). + +The driver MUST supply both device-readable or device-writeable parts +of \field{struct virtio_admin_cmd} that are a multiple of 64 bit +in length. + +The device MUST supply both device-readable or device-writeable parts +of \field{struct virtio_admin_cmd} that are larger than zero in +length. However, \field{command_specific_data} and +\field{command_specific_result} MAY be zero in length, unless +specified otherwise for the command. + +The driver MUST NOT assume that the device will initialize the whole +device-writeable part of \field{struct virtio_admin_cmd} as described in the specification; instead, +the driver MUST act as if the structure +outside the part of the buffer used by the device +is set to zero. + +If multiple administration virtqueues have been configured, +the driver MUST ensure ordering for commands +placed on different administration virtqueues.
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