[virtio-dev] [PATCH v11 09/10] admin: conformance clauses

Michael S. Tsirkin
2023-04-03T15:05:55Z

Add conformance clauses for admin commands and admin virtqueues.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

---
typo and wording fixes reported by David
clarify cmd list use can be repeated but not in parallel with other
commands, and returning same value across uses - comment by Lingshan
add conformance clauses for new error codes
---
admin.tex | 227 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 227 insertions(+)

diff --git a/admin.tex b/admin.tex
index 9552797..a398c51 100644
--- a/admin.tex
+++ b/admin.tex
@@ -283,6 +283,150 @@ \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 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 reported by the device 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 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 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. Exceptions MAY apply if the system
+configuration assures, in some way, that the driver does not
+cache the previous value of VIRTIO_ADMIN_CMD_LIST_USE,
+such as in the case of a firmware upgrade or downgrade.
+
+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 MAY issue VIRTIO_ADMIN_CMD_LIST_USE any number
+of times but MUST NOT issue VIRTIO_ADMIN_CMD_LIST_USE commands
+if any other command is currently being processed by the device.
+
+The driver SHOULD NOT set bits in device_admin_cmd_opcodes
+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
@@ -357,3 +501,86 @@ \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.
+
+\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} and
+\field{status_qualifier} 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.
+
+If the device sets \field{status} to either VIRTIO_ADMIN_STATUS_EAGAIN
+or VIRTIO_ADMIN_STATUS_ENOMEM, then the command MUST NOT
+have any side effects, making it safe to retry.
+
+\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.
+
+The driver SHOULD retry a command that completed with
+\field{status} VIRTIO_ADMIN_STATUS_EAGAIN.
--
MST