text: /******************************************************************************
   * event_channel.h
   *
   * Event channels between domains.
   *
   * Permission is hereby granted, free of charge, to any person obtaining a copy
   * of this software and associated documentation files (the "Software"), to
   * deal in the Software without restriction, including without limitation the
   * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
   * sell copies of the Software, and to permit persons to whom the Software is
   * furnished to do so, subject to the following conditions:
   *
   * The above copyright notice and this permission notice shall be included in
   * all copies or substantial portions of the Software.
   *
   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
   * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
   * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
   * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
   * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
   * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
   * DEALINGS IN THE SOFTWARE.
   *
   * 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)
   * `
   * @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
  /* ` } */
  
  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;
  
  /*
   * 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;
  
  /*
   * 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;
  
  /*
   * 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;
  
  /*
   * 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;
  
  /*
   * 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;
  
  /*
   * 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;
  
  /*
   * 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;
  
  /*
   * 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;
  
  /*
   * 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;
  
  /*
   * 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;
  
  /*
   * 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;
  
  /*
   * 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;
  
  /*
   * EVTCHNOP_set_priority: set the priority for an event channel.
   */
  struct evtchn_set_priority {
      /* IN parameters. */
      uint32_t port;
      uint32_t priority;
  };
  typedef struct evtchn_set_priority evtchn_set_priority_t;
  
  /*
   * ` enum neg_errnoval
   * ` HYPERVISOR_event_channel_op_compat(struct evtchn_op *op)
   * `
   * Superceded by new event_channel_op() hypercall since 0x00030202.
   */
  struct evtchn_op {
      uint32_t cmd; /* enum event_channel_op */
      union {
          struct evtchn_alloc_unbound    alloc_unbound;
          struct evtchn_bind_interdomain bind_interdomain;
          struct evtchn_bind_virq        bind_virq;
          struct evtchn_bind_pirq        bind_pirq;
          struct evtchn_bind_ipi         bind_ipi;
          struct evtchn_close            close;
          struct evtchn_send             send;
          struct evtchn_status           status;
          struct evtchn_bind_vcpu        bind_vcpu;
          struct evtchn_unmask           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:
   */
  