um_timetravel.h (10032B)
- /* SPDX-License-Identifier: BSD-3-Clause */
- /*
- * Copyright (C) 2019 - 2023 Intel Corporation
- */
- #ifndef _LINUX_UM_TIMETRAVEL_H
- #define _LINUX_UM_TIMETRAVEL_H
- #include <linux/types.h>
- /**
- * struct um_timetravel_msg - UM time travel message
- *
- * This is the basic message type, going in both directions.
- *
- * This is the message passed between the host (user-mode Linux instance)
- * and the calendar (the application on the other side of the socket) in
- * order to implement common scheduling.
- *
- * Whenever UML has an event it will request runtime for it from the
- * calendar, and then wait for its turn until it can run, etc. Note
- * that it will only ever request the single next runtime, i.e. multiple
- * REQUEST messages override each other.
- */
- struct um_timetravel_msg {
- /**
- * @op: operation value from &enum um_timetravel_ops
- */
- __u32 op;
- /**
- * @seq: sequence number for the message - shall be reflected in
- * the ACK response, and should be checked while processing
- * the response to see if it matches
- */
- __u32 seq;
- /**
- * @time: time in nanoseconds
- */
- __u64 time;
- };
- /* max number of file descriptors that can be sent/received in a message */
- #define UM_TIMETRAVEL_MAX_FDS 2
- /**
- * enum um_timetravel_shared_mem_fds - fds sent in ACK message for START message
- */
- enum um_timetravel_shared_mem_fds {
- /**
- * @UM_TIMETRAVEL_SHARED_MEMFD: Index of the shared memory file
- * descriptor in the control message
- */
- UM_TIMETRAVEL_SHARED_MEMFD,
- /**
- * @UM_TIMETRAVEL_SHARED_LOGFD: Index of the logging file descriptor
- * in the control message
- */
- UM_TIMETRAVEL_SHARED_LOGFD,
- UM_TIMETRAVEL_SHARED_MAX_FDS,
- };
- /**
- * enum um_timetravel_start_ack - ack-time mask for start message
- */
- enum um_timetravel_start_ack {
- /**
- * @UM_TIMETRAVEL_START_ACK_ID: client ID that controller allocated.
- */
- UM_TIMETRAVEL_START_ACK_ID = 0xffff,
- };
- /**
- * enum um_timetravel_ops - Operation codes
- */
- enum um_timetravel_ops {
- /**
- * @UM_TIMETRAVEL_ACK: response (ACK) to any previous message,
- * this usually doesn't carry any data in the 'time' field
- * unless otherwise specified below, note: while using shared
- * memory no ACK for WAIT and RUN messages, for more info see
- * &struct um_timetravel_schedshm.
- */
- UM_TIMETRAVEL_ACK = 0,
- /**
- * @UM_TIMETRAVEL_START: initialize the connection, the time
- * field contains an (arbitrary) ID to possibly be able
- * to distinguish the connections.
- */
- UM_TIMETRAVEL_START = 1,
- /**
- * @UM_TIMETRAVEL_REQUEST: request to run at the given time
- * (host -> calendar)
- */
- UM_TIMETRAVEL_REQUEST = 2,
- /**
- * @UM_TIMETRAVEL_WAIT: Indicate waiting for the previously requested
- * runtime, new requests may be made while waiting (e.g. due to
- * interrupts); the time field is ignored. The calendar must process
- * this message and later send a %UM_TIMETRAVEL_RUN message when
- * the host can run again.
- * (host -> calendar)
- */
- UM_TIMETRAVEL_WAIT = 3,
- /**
- * @UM_TIMETRAVEL_GET: return the current time from the calendar in the
- * ACK message, the time in the request message is ignored
- * (host -> calendar)
- */
- UM_TIMETRAVEL_GET = 4,
- /**
- * @UM_TIMETRAVEL_UPDATE: time update to the calendar, must be sent e.g.
- * before kicking an interrupt to another calendar
- * (host -> calendar)
- */
- UM_TIMETRAVEL_UPDATE = 5,
- /**
- * @UM_TIMETRAVEL_RUN: run time request granted, current time is in
- * the time field
- * (calendar -> host)
- */
- UM_TIMETRAVEL_RUN = 6,
- /**
- * @UM_TIMETRAVEL_FREE_UNTIL: Enable free-running until the given time,
- * this is a message from the calendar telling the host that it can
- * freely do its own scheduling for anything before the indicated
- * time.
- * Note that if a calendar sends this message once, the host may
- * assume that it will also do so in the future, if it implements
- * wraparound semantics for the time field.
- * (calendar -> host)
- */
- UM_TIMETRAVEL_FREE_UNTIL = 7,
- /**
- * @UM_TIMETRAVEL_GET_TOD: Return time of day, typically used once at
- * boot by the virtual machines to get a synchronized time from
- * the simulation.
- */
- UM_TIMETRAVEL_GET_TOD = 8,
- /**
- * @UM_TIMETRAVEL_BROADCAST: Send/Receive a broadcast message.
- * This message can be used to sync all components in the system
- * with a single message, if the calender gets the message, the
- * calender broadcast the message to all components, and if a
- * component receives it it should act based on it e.g print a
- * message to it's log system.
- * (calendar <-> host)
- */
- UM_TIMETRAVEL_BROADCAST = 9,
- };
- /* version of struct um_timetravel_schedshm */
- #define UM_TIMETRAVEL_SCHEDSHM_VERSION 2
- /**
- * enum um_timetravel_schedshm_cap - time travel capabilities of every client
- *
- * These flags must be set immediately after processing the ACK to
- * the START message, before sending any message to the controller.
- */
- enum um_timetravel_schedshm_cap {
- /**
- * @UM_TIMETRAVEL_SCHEDSHM_CAP_TIME_SHARE: client can read current time
- * update internal time request to shared memory and read
- * free until and send no Ack on RUN and doesn't expect ACK on
- * WAIT.
- */
- UM_TIMETRAVEL_SCHEDSHM_CAP_TIME_SHARE = 0x1,
- };
- /**
- * enum um_timetravel_schedshm_flags - time travel flags of every client
- */
- enum um_timetravel_schedshm_flags {
- /**
- * @UM_TIMETRAVEL_SCHEDSHM_FLAGS_REQ_RUN: client has a request to run.
- * It's set by client when it has a request to run, if (and only
- * if) the @running_id points to a client that is able to use
- * shared memory, i.e. has %UM_TIMETRAVEL_SCHEDSHM_CAP_TIME_SHARE
- * (this includes the client itself). Otherwise, a message must
- * be used.
- */
- UM_TIMETRAVEL_SCHEDSHM_FLAGS_REQ_RUN = 0x1,
- };
- /**
- * DOC: Time travel shared memory overview
- *
- * The main purpose of the shared memory is to avoid all time travel message
- * that don't need any action, for example current time can be held in shared
- * memory without the need of any client to send a message UM_TIMETRAVEL_GET
- * in order to know what's the time.
- *
- * Since this is shared memory with all clients and controller and controller
- * creates the shared memory space, all time values are absolute to controller
- * time. So first time client connects to shared memory mode it should take the
- * current_time value in shared memory and keep it internally as a diff to
- * shared memory times, and once shared memory is initialized, any interaction
- * with the controller must happen in the controller time domain, including any
- * messages (for clients that are not using shared memory, the controller will
- * handle an offset and make the clients think they start at time zero.)
- *
- * Along with the shared memory file descriptor is sent to the client a logging
- * file descriptor, to have all logs related to shared memory,
- * logged into one place. note: to have all logs synced into log file at write,
- * file should be flushed (fflush) after writing to it.
- *
- * To avoid memory corruption, we define below for each field who can write to
- * it at what time, defined in the structure fields.
- *
- * To avoid having to pack this struct, all fields in it must be naturally aligned
- * (i.e. aligned to their size).
- */
- /**
- * union um_timetravel_schedshm_client - UM time travel client struct
- *
- * Every entity using the shared memory including the controller has a place in
- * the um_timetravel_schedshm clients array, that holds info related to the client
- * using the shared memory, and can be set only by the client after it gets the
- * fd memory.
- *
- * @capa: bit fields with client capabilities see
- * &enum um_timetravel_schedshm_cap, set by client once after getting the
- * shared memory file descriptor.
- * @flags: bit fields for flags see &enum um_timetravel_schedshm_flags for doc.
- * @req_time: request time to run, set by client on every request it needs.
- * @name: unique id sent to the controller by client with START message.
- */
- union um_timetravel_schedshm_client {
- struct {
- __u32 capa;
- __u32 flags;
- __u64 req_time;
- __u64 name;
- };
- char reserve[128]; /* reserved for future usage */
- };
- /**
- * struct um_timetravel_schedshm - UM time travel shared memory struct
- *
- * @hdr: header fields:
- * @version: Current version struct UM_TIMETRAVEL_SCHEDSHM_VERSION,
- * set by controller once at init, clients must check this after mapping
- * and work without shared memory if they cannot handle the indicated
- * version.
- * @len: Length of all the memory including header (@hdr), clients should once
- * per connection first mmap the header and take the length (@len) to remap the entire size.
- * This is done in order to support dynamic struct size letting number of
- * clients be dynamic based on controller support.
- * @free_until: Stores the next request to run by any client, in order for the
- * current client to know how long it can still run. A client needs to (at
- * least) reload this value immediately after communicating with any other
- * client, since the controller will update this field when a new request
- * is made by any client. Clients also must update this value when they
- * insert/update an own request into the shared memory while not running
- * themselves, and the new request is before than the current value.
- * current_time: Current time, can only be set by the client in running state
- * (indicated by @running_id), though that client may only run until @free_until,
- * so it must remain smaller than @free_until.
- * @running_id: The current client in state running, set before a client is
- * notified that it's now running.
- * @max_clients: size of @clients array, set once at init by the controller.
- * @clients: clients array see &union um_timetravel_schedshm_client for doc,
- * set only by client.
- */
- struct um_timetravel_schedshm {
- union {
- struct {
- __u32 version;
- __u32 len;
- __u64 free_until;
- __u64 current_time;
- __u16 running_id;
- __u16 max_clients;
- };
- char hdr[4096]; /* align to 4K page size */
- };
- union um_timetravel_schedshm_client clients[];
- };
- #endif /* _LINUX_UM_TIMETRAVEL_H */