    /* SPDX-License-Identifier: MIT */
    /******************************************************************************
     * sched.h
     *
     * Scheduler state interactions
     *
     * Copyright (c) 2005, Keir Fraser <keir@xensource.com>
     */

    #ifndef __XEN_PUBLIC_SCHED_H__
    #define __XEN_PUBLIC_SCHED_H__

    #include "event_channel.h"

    /*
     * `incontents 150 sched Guest Scheduler Operations
     *
     * The SCHEDOP interface provides mechanisms for a guest to interact
     * with the scheduler, including yield, blocking and shutting itself
     * down.
     */

    /*
     * The prototype for this hypercall is:
     * ` long HYPERVISOR_sched_op(enum sched_op cmd, void *arg, ...)
     *
     * @cmd == SCHEDOP_??? (scheduler operation).
     * @arg == Operation-specific extra argument(s), as described below.
     * ...  == Additional Operation-specific extra arguments, described below.
     *
     * Versions of Xen prior to 3.0.2 provided only the following legacy version
     * of this hypercall, supporting only the commands yield, block and shutdown:
     *  long sched_op(int cmd, unsigned long arg)
     * @cmd == SCHEDOP_??? (scheduler operation).
     * @arg == 0               (SCHEDOP_yield and SCHEDOP_block)
     *      == SHUTDOWN_* code (SCHEDOP_shutdown)
     *
     * This legacy version is available to new guests as:
     * ` long HYPERVISOR_sched_op_compat(enum sched_op cmd, unsigned long arg)
     */
    /* [see __HYPERVISOR_sched_op] */
    /* [see __HYPERVISOR_sched_op_compat] */

    /* ` enum sched_op { // SCHEDOP_* => struct sched_* */
    /*
     * Voluntarily yield the CPU.
     * @arg == NULL.
     */
    #define SCHEDOP_yield       0

    /*
     * Block execution of this VCPU until an event is received for processing.
     * If called with event upcalls masked, this operation will atomically
     * reenable event delivery and check for pending events before blocking the
     * VCPU. This avoids a "wakeup waiting" race.
     * @arg == NULL.
     */
    #define SCHEDOP_block       1

    /*
     * Halt execution of this domain (all VCPUs) and notify the system controller.
     * @arg == pointer to sched_shutdown_t structure.
     *
     * If the sched_shutdown_t reason is SHUTDOWN_suspend then
     * x86 PV guests must also set RDX (EDX for 32-bit guests) to the MFN
     * of the guest's start info page.  RDX/EDX is the third hypercall
     * argument.
     *
     * In addition, which reason is SHUTDOWN_suspend this hypercall
     * returns 1 if suspend was cancelled or the domain was merely
     * checkpointed, and 0 if it is resuming in a new domain.
     */
    #define SCHEDOP_shutdown    2

    /*
     * Poll a set of event-channel ports. Return when one or more are pending. An
     * optional timeout may be specified.
     * @arg == pointer to sched_poll_t structure.
     */
    #define SCHEDOP_poll        3

    /*
     * Declare a shutdown for another domain. The main use of this function is
     * in interpreting shutdown requests and reasons for fully-virtualized
     * domains.  A para-virtualized domain may use SCHEDOP_shutdown directly.
     * @arg == pointer to sched_remote_shutdown_t structure.
     */
    #define SCHEDOP_remote_shutdown        4

    /*
     * Latch a shutdown code, so that when the domain later shuts down it
     * reports this code to the control tools.
     * @arg == sched_shutdown_t, as for SCHEDOP_shutdown.
     */
    #define SCHEDOP_shutdown_code 5

    /*
     * Setup, poke and destroy a domain watchdog timer.
     * @arg == pointer to sched_watchdog_t structure.
     * With id == 0, setup a domain watchdog timer to cause domain shutdown
     *               after timeout, returns watchdog id.
     * With id != 0 and timeout == 0, destroy domain watchdog timer.
     * With id != 0 and timeout != 0, poke watchdog timer and set new timeout.
     */
    #define SCHEDOP_watchdog    6

    /*
     * Override the current vcpu affinity by pinning it to one physical cpu or
     * undo this override restoring the previous affinity.
     * @arg == pointer to sched_pin_override_t structure.
     *
     * A negative pcpu value will undo a previous pin override and restore the
     * previous cpu affinity.
     * This call is allowed for the hardware domain only and requires the cpu
     * to be part of the domain's cpupool.
     */
    #define SCHEDOP_pin_override 7
    /* ` } */

    struct sched_shutdown {
        unsigned int reason; /* SHUTDOWN_* => enum sched_shutdown_reason */
    };
    typedef struct sched_shutdown sched_shutdown_t;
    DEFINE_XEN_GUEST_HANDLE(sched_shutdown_t);
    /* [see SCHEDOP_shutdown] */

    struct sched_poll {
        XEN_GUEST_HANDLE(evtchn_port_t) ports;
        unsigned int nr_ports;
        uint64_t timeout;
    };
    typedef struct sched_poll sched_poll_t;
    DEFINE_XEN_GUEST_HANDLE(sched_poll_t);
    /* [see SCHEDOP_poll] */

    struct sched_remote_shutdown {
        domid_t domain_id;         /* Remote domain ID */
        unsigned int reason;       /* SHUTDOWN_* => enum sched_shutdown_reason */
    };
    typedef struct sched_remote_shutdown sched_remote_shutdown_t;
    DEFINE_XEN_GUEST_HANDLE(sched_remote_shutdown_t);
    /* [see SCHEDOP_remote_shutdown] */

    struct sched_watchdog {
        uint32_t id;                /* watchdog ID */
        uint32_t timeout;           /* timeout */
    };
    typedef struct sched_watchdog sched_watchdog_t;
    DEFINE_XEN_GUEST_HANDLE(sched_watchdog_t);
    /* [see SCHEDOP_watchdog] */

    struct sched_pin_override {
        int32_t pcpu;
    };
    typedef struct sched_pin_override sched_pin_override_t;
    DEFINE_XEN_GUEST_HANDLE(sched_pin_override_t);
    /* [see SCHEDOP_pin_override] */

    /*
     * Reason codes for SCHEDOP_shutdown. These may be interpreted by control
     * software to determine the appropriate action. For the most part, Xen does
     * not care about the shutdown code.
     */
    /* ` enum sched_shutdown_reason { */
    #define SHUTDOWN_poweroff   0  /* Domain exited normally. Clean up and kill. */
    #define SHUTDOWN_reboot     1  /* Clean up, kill, and then restart.          */
    #define SHUTDOWN_suspend    2  /* Clean up, save suspend info, kill.         */
    #define SHUTDOWN_crash      3  /* Tell controller we've crashed.             */
    #define SHUTDOWN_watchdog   4  /* Restart because watchdog time expired.     */

    /*
     * Domain asked to perform 'soft reset' for it. The expected behavior is to
     * reset internal Xen state for the domain returning it to the point where it
     * was created but leaving the domain's memory contents and vCPU contexts
     * intact. This will allow the domain to start over and set up all Xen specific
     * interfaces again.
     */
    #define SHUTDOWN_soft_reset 5
    #define SHUTDOWN_MAX        5  /* Maximum valid shutdown reason.             */
    /* ` } */

    #endif /* __XEN_PUBLIC_SCHED_H__ */

    /*
     * Local variables:
     * mode: C
     * c-file-style: "BSD"
     * c-basic-offset: 4
     * tab-width: 4
     * indent-tabs-mode: nil
     * End:
     */