    /* SPDX-License-Identifier: MIT */
    /******************************************************************************
     * event_channel.h
     *
     * Event channels between domains.
     *
     * Copyright (c) 2003-2004, K A Fraser.
     */

    #ifndef __XEN_PUBLIC_EVENT_CHANNEL_H__
    #define __XEN_PUBLIC_EVENT_CHANNEL_H__

    #include "xen.h"

    /*
     * `incontents 150 evtchn Event Channels
     *
     * Event channels are the basic primitive provided by Xen for event
     * notifications. An event is the Xen equivalent of a hardware
     * interrupt. They essentially store one bit of information, the event
     * of interest is signalled by transitioning this bit from 0 to 1.
     *
     * Notifications are received by a guest via an upcall from Xen,
     * indicating when an event arrives (setting the bit). Further
     * notifications are masked until the bit is cleared again (therefore,
     * guests must check the value of the bit after re-enabling event
     * delivery to ensure no missed notifications).
     *
     * Event notifications can be masked by setting a flag; this is
     * equivalent to disabling interrupts and can be used to ensure
     * atomicity of certain operations in the guest kernel.
     *
     * Event channels are represented by the evtchn_* fields in
     * struct shared_info and struct vcpu_info.
     */

    /*
     * ` enum neg_errnoval
     * ` HYPERVISOR_event_channel_op(enum event_channel_op cmd, void *args)
     * ` [see __HYPERVISOR_event_channel_op]
     * `
     * @cmd  == EVTCHNOP_* (event-channel operation).
     * @args == struct evtchn_* Operation-specific extra arguments (NULL if none).
     */

    /* ` enum event_channel_op { // EVTCHNOP_* => struct evtchn_* */
    #define EVTCHNOP_bind_interdomain 0
    #define EVTCHNOP_bind_virq        1
    #define EVTCHNOP_bind_pirq        2
    #define EVTCHNOP_close            3
    #define EVTCHNOP_send             4
    #define EVTCHNOP_status           5
    #define EVTCHNOP_alloc_unbound    6
    #define EVTCHNOP_bind_ipi         7
    #define EVTCHNOP_bind_vcpu        8
    #define EVTCHNOP_unmask           9
    #define EVTCHNOP_reset           10
    #define EVTCHNOP_init_control    11
    #define EVTCHNOP_expand_array    12
    #define EVTCHNOP_set_priority    13
    #ifdef __XEN__
    #define EVTCHNOP_reset_cont      14
    #endif
    /* ` } */

    typedef uint32_t evtchn_port_t;
    DEFINE_XEN_GUEST_HANDLE(evtchn_port_t);

    /*
     * EVTCHNOP_alloc_unbound: Allocate a port in domain <dom> and mark as
     * accepting interdomain bindings from domain <remote_dom>. A fresh port
     * is allocated in <dom> and returned as <port>.
     * NOTES:
     *  1. If the caller is unprivileged then <dom> must be DOMID_SELF.
     *  2. <remote_dom> may be DOMID_SELF, allowing loopback connections.
     */
    struct evtchn_alloc_unbound {
        /* IN parameters */
        domid_t dom, remote_dom;
        /* OUT parameters */
        evtchn_port_t port;
    };
    typedef struct evtchn_alloc_unbound evtchn_alloc_unbound_t;
    /* [see EVTCHNOP_alloc_unbound] */

    /*
     * EVTCHNOP_bind_interdomain: Construct an interdomain event channel between
     * the calling domain and <remote_dom>. <remote_dom,remote_port> must identify
     * a port that is unbound and marked as accepting bindings from the calling
     * domain. A fresh port is allocated in the calling domain and returned as
     * <local_port>.
     *
     * In case the peer domain has already tried to set our event channel
     * pending, before it was bound, EVTCHNOP_bind_interdomain always sets
     * the local event channel pending.
     *
     * The usual pattern of use, in the guest's upcall (or subsequent
     * handler) is as follows: (Re-enable the event channel for subsequent
     * signalling and then) check for the existence of whatever condition
     * is being waited for by other means, and take whatever action is
     * needed (if any).
     *
     * NOTES:
     *  1. <remote_dom> may be DOMID_SELF, allowing loopback connections.
     */
    struct evtchn_bind_interdomain {
        /* IN parameters. */
        domid_t remote_dom;
        evtchn_port_t remote_port;
        /* OUT parameters. */
        evtchn_port_t local_port;
    };
    typedef struct evtchn_bind_interdomain evtchn_bind_interdomain_t;
    /* [see EVTCHNOP_bind_interdomain] */

    /*
     * EVTCHNOP_bind_virq: Bind a local event channel to VIRQ <irq> on specified
     * vcpu.
     * NOTES:
     *  1. Virtual IRQs are classified as per-vcpu or global. See the VIRQ list
     *     in xen.h for the classification of each VIRQ.
     *  2. Global VIRQs must be allocated on VCPU0 but can subsequently be
     *     re-bound via EVTCHNOP_bind_vcpu.
     *  3. Per-vcpu VIRQs may be bound to at most one event channel per vcpu.
     *     The allocated event channel is bound to the specified vcpu and the
     *     binding cannot be changed.
     */
    struct evtchn_bind_virq {
        /* IN parameters. */
        uint32_t virq; /* enum virq */
        uint32_t vcpu;
        /* OUT parameters. */
        evtchn_port_t port;
    };
    typedef struct evtchn_bind_virq evtchn_bind_virq_t;
    /* [see EVTCHNOP_bind_virq] */

    /*
     * EVTCHNOP_bind_pirq: Bind a local event channel to a real IRQ (PIRQ <irq>).
     * NOTES:
     *  1. A physical IRQ may be bound to at most one event channel per domain.
     *  2. Only a sufficiently-privileged domain may bind to a physical IRQ.
     */
    struct evtchn_bind_pirq {
        /* IN parameters. */
        uint32_t pirq;
    #define BIND_PIRQ__WILL_SHARE 1
        uint32_t flags; /* BIND_PIRQ__* */
        /* OUT parameters. */
        evtchn_port_t port;
    };
    typedef struct evtchn_bind_pirq evtchn_bind_pirq_t;
    /* [see EVTCHNOP_bind_pirq] */

    /*
     * EVTCHNOP_bind_ipi: Bind a local event channel to receive events.
     * NOTES:
     *  1. The allocated event channel is bound to the specified vcpu. The binding
     *     may not be changed.
     */
    struct evtchn_bind_ipi {
        uint32_t vcpu;
        /* OUT parameters. */
        evtchn_port_t port;
    };
    typedef struct evtchn_bind_ipi evtchn_bind_ipi_t;
    /* [see EVTCHNOP_bind_ipi] */

    /*
     * EVTCHNOP_close: Close a local event channel <port>. If the channel is
     * interdomain then the remote end is placed in the unbound state
     * (EVTCHNSTAT_unbound), awaiting a new connection.
     */
    struct evtchn_close {
        /* IN parameters. */
        evtchn_port_t port;
    };
    typedef struct evtchn_close evtchn_close_t;
    /* [see EVTCHNOP_close] */

    /*
     * EVTCHNOP_send: Send an event to the remote end of the channel whose local
     * endpoint is <port>.
     */
    struct evtchn_send {
        /* IN parameters. */
        evtchn_port_t port;
    };
    typedef struct evtchn_send evtchn_send_t;
    /* [see EVTCHNOP_send] */

    /*
     * EVTCHNOP_status: Get the current status of the communication channel which
     * has an endpoint at <dom, port>.
     * NOTES:
     *  1. <dom> may be specified as DOMID_SELF.
     *  2. Only a sufficiently-privileged domain may obtain the status of an event
     *     channel for which <dom> is not DOMID_SELF.
     */
    struct evtchn_status {
        /* IN parameters */
        domid_t  dom;
        evtchn_port_t port;
        /* OUT parameters */
    #define EVTCHNSTAT_closed       0  /* Channel is not in use.                 */
    #define EVTCHNSTAT_unbound      1  /* Channel is waiting interdom connection.*/
    #define EVTCHNSTAT_interdomain  2  /* Channel is connected to remote domain. */
    #define EVTCHNSTAT_pirq         3  /* Channel is bound to a phys IRQ line.   */
    #define EVTCHNSTAT_virq         4  /* Channel is bound to a virtual IRQ line */
    #define EVTCHNSTAT_ipi          5  /* Channel is bound to a virtual IPI line */
        uint32_t status;
        uint32_t vcpu;                 /* VCPU to which this channel is bound.   */
        union {
            struct {
                domid_t dom;
            } unbound;                 /* EVTCHNSTAT_unbound */
            struct {
                domid_t dom;
                evtchn_port_t port;
            } interdomain;             /* EVTCHNSTAT_interdomain */
            uint32_t pirq;             /* EVTCHNSTAT_pirq        */
            uint32_t virq;             /* EVTCHNSTAT_virq        */
        } u;
    };
    typedef struct evtchn_status evtchn_status_t;
    /* [see EVTCHNOP_status] */

    /*
     * EVTCHNOP_bind_vcpu: Specify which vcpu a channel should notify when an
     * event is pending.
     * NOTES:
     *  1. IPI-bound channels always notify the vcpu specified at bind time.
     *     This binding cannot be changed.
     *  2. Per-VCPU VIRQ channels always notify the vcpu specified at bind time.
     *     This binding cannot be changed.
     *  3. All other channels notify vcpu0 by default. This default is set when
     *     the channel is allocated (a port that is freed and subsequently reused
     *     has its binding reset to vcpu0).
     */
    struct evtchn_bind_vcpu {
        /* IN parameters. */
        evtchn_port_t port;
        uint32_t vcpu;
    };
    typedef struct evtchn_bind_vcpu evtchn_bind_vcpu_t;
    /* [see EVTCHNOP_bind_vcpu] */

    /*
     * EVTCHNOP_unmask: Unmask the specified local event-channel port and deliver
     * a notification to the appropriate VCPU if an event is pending.
     */
    struct evtchn_unmask {
        /* IN parameters. */
        evtchn_port_t port;
    };
    typedef struct evtchn_unmask evtchn_unmask_t;
    /* [see EVTCHNOP_unmask] */

    /*
     * EVTCHNOP_reset: Close all event channels associated with specified domain.
     * NOTES:
     *  1. <dom> may be specified as DOMID_SELF.
     *  2. Only a sufficiently-privileged domain may specify other than DOMID_SELF.
     *  3. Destroys all control blocks and event array, resets event channel
     *     operations to 2-level ABI if called with <dom> == DOMID_SELF and FIFO
     *     ABI was used. Guests should not bind events during EVTCHNOP_reset call
     *     as these events are likely to be lost.
     */
    struct evtchn_reset {
        /* IN parameters. */
        domid_t dom;
    };
    typedef struct evtchn_reset evtchn_reset_t;
    /* [see EVTCHNOP_reset] */

    /*
     * EVTCHNOP_init_control: initialize the control block for the FIFO ABI.
     *
     * Note: any events that are currently pending will not be resent and
     * will be lost.  Guests should call this before binding any event to
     * avoid losing any events.
     */
    struct evtchn_init_control {
        /* IN parameters. */
        uint64_t control_gfn;
        uint32_t offset;
        uint32_t vcpu;
        /* OUT parameters. */
        uint8_t link_bits;
        uint8_t _pad[7];
    };
    typedef struct evtchn_init_control evtchn_init_control_t;
    /* [see EVTCHNOP_init_control] */

    /*
     * EVTCHNOP_expand_array: add an additional page to the event array.
     */
    struct evtchn_expand_array {
        /* IN parameters. */
        uint64_t array_gfn;
    };
    typedef struct evtchn_expand_array evtchn_expand_array_t;
    /* [see EVTCHNOP_expand_array] */

    /*
     * EVTCHNOP_set_priority: set the priority for an event channel.
     */
    struct evtchn_set_priority {
        /* IN parameters. */
        evtchn_port_t port;
        uint32_t priority;
    };
    typedef struct evtchn_set_priority evtchn_set_priority_t;
    /* [see EVTCHNOP_set_priority] */

    /*
     * ` enum neg_errnoval
     * ` HYPERVISOR_event_channel_op_compat(struct evtchn_op *op)
     * ` [see __HYPERVISOR_event_channel_op_compat]
     * `
     * Superceded by new event_channel_op() hypercall since 0x00030202.
     */
    struct evtchn_op {
        uint32_t cmd; /* enum event_channel_op */
        union {
            evtchn_alloc_unbound_t    alloc_unbound;
            evtchn_bind_interdomain_t bind_interdomain;
            evtchn_bind_virq_t        bind_virq;
            evtchn_bind_pirq_t        bind_pirq;
            evtchn_bind_ipi_t         bind_ipi;
            evtchn_close_t            close;
            evtchn_send_t             send;
            evtchn_status_t           status;
            evtchn_bind_vcpu_t        bind_vcpu;
            evtchn_unmask_t           unmask;
        } u;
    };
    typedef struct evtchn_op evtchn_op_t;
    DEFINE_XEN_GUEST_HANDLE(evtchn_op_t);

    /*
     * 2-level ABI
     */

    #define EVTCHN_2L_NR_CHANNELS (sizeof(xen_ulong_t) * sizeof(xen_ulong_t) * 64)

    /*
     * FIFO ABI
     */

    /* Events may have priorities from 0 (highest) to 15 (lowest). */
    #define EVTCHN_FIFO_PRIORITY_MAX     0
    #define EVTCHN_FIFO_PRIORITY_DEFAULT 7
    #define EVTCHN_FIFO_PRIORITY_MIN     15

    #define EVTCHN_FIFO_MAX_QUEUES (EVTCHN_FIFO_PRIORITY_MIN + 1)

    typedef uint32_t event_word_t;

    #define EVTCHN_FIFO_PENDING 31
    #define EVTCHN_FIFO_MASKED  30
    #define EVTCHN_FIFO_LINKED  29
    #define EVTCHN_FIFO_BUSY    28

    #define EVTCHN_FIFO_LINK_BITS 17
    #define EVTCHN_FIFO_LINK_MASK ((1 << EVTCHN_FIFO_LINK_BITS) - 1)

    #define EVTCHN_FIFO_NR_CHANNELS (1 << EVTCHN_FIFO_LINK_BITS)

    struct evtchn_fifo_control_block {
        uint32_t ready;
        uint32_t _rsvd;
        uint32_t head[EVTCHN_FIFO_MAX_QUEUES];
    };
    typedef struct evtchn_fifo_control_block evtchn_fifo_control_block_t;

    #endif /* __XEN_PUBLIC_EVENT_CHANNEL_H__ */

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