From 88ce642492339f49a0b391af40e5798c08948e49 Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 13 Feb 2020 14:26:47 +0100 Subject: um: Implement time-travel=ext This implements synchronized time-travel mode which - using a special application on a unix socket - lets multiple machines take part in a time-travelling simulation together. The protocol for the unix domain socket is defined in the new file include/uapi/linux/um_timetravel.h. Signed-off-by: Johannes Berg Signed-off-by: Richard Weinberger --- include/uapi/linux/um_timetravel.h | 128 +++++++++++++++++++++++++++++++++++++ 1 file changed, 128 insertions(+) create mode 100644 include/uapi/linux/um_timetravel.h (limited to 'include/uapi') diff --git a/include/uapi/linux/um_timetravel.h b/include/uapi/linux/um_timetravel.h new file mode 100644 index 000000000000..ca3238222b6d --- /dev/null +++ b/include/uapi/linux/um_timetravel.h @@ -0,0 +1,128 @@ +/* + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + * + * Copyright (C) 2019 Intel Corporation + */ +#ifndef _UAPI_LINUX_UM_TIMETRAVEL_H +#define _UAPI_LINUX_UM_TIMETRAVEL_H +#include + +/** + * 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; +}; + +/** + * 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 + */ + 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, +}; + +#endif /* _UAPI_LINUX_UM_TIMETRAVEL_H */ -- cgit v1.2.3