include/hw/xen/interface/event_channel.h

   1 /* SPDX-License-Identifier: MIT */
   2 /******************************************************************************
   3  * event_channel.h
   4  *
   5  * Event channels between domains.
   6  *
   7  * Copyright (c) 2003-2004, K A Fraser.
   8  */
   9
  10 #ifndef __XEN_PUBLIC_EVENT_CHANNEL_H__
  11 #define __XEN_PUBLIC_EVENT_CHANNEL_H__
  12
  13 #include "xen.h"
  14
  15 /*
  16  * `incontents 150 evtchn Event Channels
  17  *
  18  * Event channels are the basic primitive provided by Xen for event
  19  * notifications. An event is the Xen equivalent of a hardware
  20  * interrupt. They essentially store one bit of information, the event
  21  * of interest is signalled by transitioning this bit from 0 to 1.
  22  *
  23  * Notifications are received by a guest via an upcall from Xen,
  24  * indicating when an event arrives (setting the bit). Further
  25  * notifications are masked until the bit is cleared again (therefore,
  26  * guests must check the value of the bit after re-enabling event
  27  * delivery to ensure no missed notifications).
  28  *
  29  * Event notifications can be masked by setting a flag; this is
  30  * equivalent to disabling interrupts and can be used to ensure
  31  * atomicity of certain operations in the guest kernel.
  32  *
  33  * Event channels are represented by the evtchn_* fields in
  34  * struct shared_info and struct vcpu_info.
  35  */
  36
  37 /*
  38  * ` enum neg_errnoval
  39  * ` HYPERVISOR_event_channel_op(enum event_channel_op cmd, void *args)
  40  * `
  41  * @cmd  == EVTCHNOP_* (event-channel operation).
  42  * @args == struct evtchn_* Operation-specific extra arguments (NULL if none).
  43  */
  44
  45 /* ` enum event_channel_op { // EVTCHNOP_* => struct evtchn_* */
  46 #define EVTCHNOP_bind_interdomain 0
  47 #define EVTCHNOP_bind_virq        1
  48 #define EVTCHNOP_bind_pirq        2
  49 #define EVTCHNOP_close            3
  50 #define EVTCHNOP_send             4
  51 #define EVTCHNOP_status           5
  52 #define EVTCHNOP_alloc_unbound    6
  53 #define EVTCHNOP_bind_ipi         7
  54 #define EVTCHNOP_bind_vcpu        8
  55 #define EVTCHNOP_unmask           9
  56 #define EVTCHNOP_reset           10
  57 #define EVTCHNOP_init_control    11
  58 #define EVTCHNOP_expand_array    12
  59 #define EVTCHNOP_set_priority    13
  60 #ifdef __XEN__
  61 #define EVTCHNOP_reset_cont      14
  62 #endif
  63 /* ` } */
  64
  65 typedef uint32_t evtchn_port_t;
  66 DEFINE_XEN_GUEST_HANDLE(evtchn_port_t);
  67
  68 /*
  69  * EVTCHNOP_alloc_unbound: Allocate a port in domain <dom> and mark as
  70  * accepting interdomain bindings from domain <remote_dom>. A fresh port
  71  * is allocated in <dom> and returned as <port>.
  72  * NOTES:
  73  *  1. If the caller is unprivileged then <dom> must be DOMID_SELF.
  74  *  2. <remote_dom> may be DOMID_SELF, allowing loopback connections.
  75  */
  76 struct evtchn_alloc_unbound {
  77     /* IN parameters */
  78     domid_t dom, remote_dom;
  79     /* OUT parameters */
  80     evtchn_port_t port;
  81 };
  82 typedef struct evtchn_alloc_unbound evtchn_alloc_unbound_t;
  83
  84 /*
  85  * EVTCHNOP_bind_interdomain: Construct an interdomain event channel between
  86  * the calling domain and <remote_dom>. <remote_dom,remote_port> must identify
  87  * a port that is unbound and marked as accepting bindings from the calling
  88  * domain. A fresh port is allocated in the calling domain and returned as
  89  * <local_port>.
  90  *
  91  * In case the peer domain has already tried to set our event channel
  92  * pending, before it was bound, EVTCHNOP_bind_interdomain always sets
  93  * the local event channel pending.
  94  *
  95  * The usual pattern of use, in the guest's upcall (or subsequent
  96  * handler) is as follows: (Re-enable the event channel for subsequent
  97  * signalling and then) check for the existence of whatever condition
  98  * is being waited for by other means, and take whatever action is
  99  * needed (if any).
 100  *
 101  * NOTES:
 102  *  1. <remote_dom> may be DOMID_SELF, allowing loopback connections.
 103  */
 104 struct evtchn_bind_interdomain {
 105     /* IN parameters. */
 106     domid_t remote_dom;
 107     evtchn_port_t remote_port;
 108     /* OUT parameters. */
 109     evtchn_port_t local_port;
 110 };
 111 typedef struct evtchn_bind_interdomain evtchn_bind_interdomain_t;
 112
 113 /*
 114  * EVTCHNOP_bind_virq: Bind a local event channel to VIRQ <irq> on specified
 115  * vcpu.
 116  * NOTES:
 117  *  1. Virtual IRQs are classified as per-vcpu or global. See the VIRQ list
 118  *     in xen.h for the classification of each VIRQ.
 119  *  2. Global VIRQs must be allocated on VCPU0 but can subsequently be
 120  *     re-bound via EVTCHNOP_bind_vcpu.
 121  *  3. Per-vcpu VIRQs may be bound to at most one event channel per vcpu.
 122  *     The allocated event channel is bound to the specified vcpu and the
 123  *     binding cannot be changed.
 124  */
 125 struct evtchn_bind_virq {
 126     /* IN parameters. */
 127     uint32_t virq; /* enum virq */
 128     uint32_t vcpu;
 129     /* OUT parameters. */
 130     evtchn_port_t port;
 131 };
 132 typedef struct evtchn_bind_virq evtchn_bind_virq_t;
 133
 134 /*
 135  * EVTCHNOP_bind_pirq: Bind a local event channel to a real IRQ (PIRQ <irq>).
 136  * NOTES:
 137  *  1. A physical IRQ may be bound to at most one event channel per domain.
 138  *  2. Only a sufficiently-privileged domain may bind to a physical IRQ.
 139  */
 140 struct evtchn_bind_pirq {
 141     /* IN parameters. */
 142     uint32_t pirq;
 143 #define BIND_PIRQ__WILL_SHARE 1
 144     uint32_t flags; /* BIND_PIRQ__* */
 145     /* OUT parameters. */
 146     evtchn_port_t port;
 147 };
 148 typedef struct evtchn_bind_pirq evtchn_bind_pirq_t;
 149
 150 /*
 151  * EVTCHNOP_bind_ipi: Bind a local event channel to receive events.
 152  * NOTES:
 153  *  1. The allocated event channel is bound to the specified vcpu. The binding
 154  *     may not be changed.
 155  */
 156 struct evtchn_bind_ipi {
 157     uint32_t vcpu;
 158     /* OUT parameters. */
 159     evtchn_port_t port;
 160 };
 161 typedef struct evtchn_bind_ipi evtchn_bind_ipi_t;
 162
 163 /*
 164  * EVTCHNOP_close: Close a local event channel <port>. If the channel is
 165  * interdomain then the remote end is placed in the unbound state
 166  * (EVTCHNSTAT_unbound), awaiting a new connection.
 167  */
 168 struct evtchn_close {
 169     /* IN parameters. */
 170     evtchn_port_t port;
 171 };
 172 typedef struct evtchn_close evtchn_close_t;
 173
 174 /*
 175  * EVTCHNOP_send: Send an event to the remote end of the channel whose local
 176  * endpoint is <port>.
 177  */
 178 struct evtchn_send {
 179     /* IN parameters. */
 180     evtchn_port_t port;
 181 };
 182 typedef struct evtchn_send evtchn_send_t;
 183
 184 /*
 185  * EVTCHNOP_status: Get the current status of the communication channel which
 186  * has an endpoint at <dom, port>.
 187  * NOTES:
 188  *  1. <dom> may be specified as DOMID_SELF.
 189  *  2. Only a sufficiently-privileged domain may obtain the status of an event
 190  *     channel for which <dom> is not DOMID_SELF.
 191  */
 192 struct evtchn_status {
 193     /* IN parameters */
 194     domid_t  dom;
 195     evtchn_port_t port;
 196     /* OUT parameters */
 197 #define EVTCHNSTAT_closed       0  /* Channel is not in use.                 */
 198 #define EVTCHNSTAT_unbound      1  /* Channel is waiting interdom connection.*/
 199 #define EVTCHNSTAT_interdomain  2  /* Channel is connected to remote domain. */
 200 #define EVTCHNSTAT_pirq         3  /* Channel is bound to a phys IRQ line.   */
 201 #define EVTCHNSTAT_virq         4  /* Channel is bound to a virtual IRQ line */
 202 #define EVTCHNSTAT_ipi          5  /* Channel is bound to a virtual IPI line */
 203     uint32_t status;
 204     uint32_t vcpu;                 /* VCPU to which this channel is bound.   */
 205     union {
 206         struct {
 207             domid_t dom;
 208         } unbound;                 /* EVTCHNSTAT_unbound */
 209         struct {
 210             domid_t dom;
 211             evtchn_port_t port;
 212         } interdomain;             /* EVTCHNSTAT_interdomain */
 213         uint32_t pirq;             /* EVTCHNSTAT_pirq        */
 214         uint32_t virq;             /* EVTCHNSTAT_virq        */
 215     } u;
 216 };
 217 typedef struct evtchn_status evtchn_status_t;
 218
 219 /*
 220  * EVTCHNOP_bind_vcpu: Specify which vcpu a channel should notify when an
 221  * event is pending.
 222  * NOTES:
 223  *  1. IPI-bound channels always notify the vcpu specified at bind time.
 224  *     This binding cannot be changed.
 225  *  2. Per-VCPU VIRQ channels always notify the vcpu specified at bind time.
 226  *     This binding cannot be changed.
 227  *  3. All other channels notify vcpu0 by default. This default is set when
 228  *     the channel is allocated (a port that is freed and subsequently reused
 229  *     has its binding reset to vcpu0).
 230  */
 231 struct evtchn_bind_vcpu {
 232     /* IN parameters. */
 233     evtchn_port_t port;
 234     uint32_t vcpu;
 235 };
 236 typedef struct evtchn_bind_vcpu evtchn_bind_vcpu_t;
 237
 238 /*
 239  * EVTCHNOP_unmask: Unmask the specified local event-channel port and deliver
 240  * a notification to the appropriate VCPU if an event is pending.
 241  */
 242 struct evtchn_unmask {
 243     /* IN parameters. */
 244     evtchn_port_t port;
 245 };
 246 typedef struct evtchn_unmask evtchn_unmask_t;
 247
 248 /*
 249  * EVTCHNOP_reset: Close all event channels associated with specified domain.
 250  * NOTES:
 251  *  1. <dom> may be specified as DOMID_SELF.
 252  *  2. Only a sufficiently-privileged domain may specify other than DOMID_SELF.
 253  *  3. Destroys all control blocks and event array, resets event channel
 254  *     operations to 2-level ABI if called with <dom> == DOMID_SELF and FIFO
 255  *     ABI was used. Guests should not bind events during EVTCHNOP_reset call
 256  *     as these events are likely to be lost.
 257  */
 258 struct evtchn_reset {
 259     /* IN parameters. */
 260     domid_t dom;
 261 };
 262 typedef struct evtchn_reset evtchn_reset_t;
 263
 264 /*
 265  * EVTCHNOP_init_control: initialize the control block for the FIFO ABI.
 266  *
 267  * Note: any events that are currently pending will not be resent and
 268  * will be lost.  Guests should call this before binding any event to
 269  * avoid losing any events.
 270  */
 271 struct evtchn_init_control {
 272     /* IN parameters. */
 273     uint64_t control_gfn;
 274     uint32_t offset;
 275     uint32_t vcpu;
 276     /* OUT parameters. */
 277     uint8_t link_bits;
 278     uint8_t _pad[7];
 279 };
 280 typedef struct evtchn_init_control evtchn_init_control_t;
 281
 282 /*
 283  * EVTCHNOP_expand_array: add an additional page to the event array.
 284  */
 285 struct evtchn_expand_array {
 286     /* IN parameters. */
 287     uint64_t array_gfn;
 288 };
 289 typedef struct evtchn_expand_array evtchn_expand_array_t;
 290
 291 /*
 292  * EVTCHNOP_set_priority: set the priority for an event channel.
 293  */
 294 struct evtchn_set_priority {
 295     /* IN parameters. */
 296     evtchn_port_t port;
 297     uint32_t priority;
 298 };
 299 typedef struct evtchn_set_priority evtchn_set_priority_t;
 300
 301 /*
 302  * ` enum neg_errnoval
 303  * ` HYPERVISOR_event_channel_op_compat(struct evtchn_op *op)
 304  * `
 305  * Superceded by new event_channel_op() hypercall since 0x00030202.
 306  */
 307 struct evtchn_op {
 308     uint32_t cmd; /* enum event_channel_op */
 309     union {
 310         evtchn_alloc_unbound_t    alloc_unbound;
 311         evtchn_bind_interdomain_t bind_interdomain;
 312         evtchn_bind_virq_t        bind_virq;
 313         evtchn_bind_pirq_t        bind_pirq;
 314         evtchn_bind_ipi_t         bind_ipi;
 315         evtchn_close_t            close;
 316         evtchn_send_t             send;
 317         evtchn_status_t           status;
 318         evtchn_bind_vcpu_t        bind_vcpu;
 319         evtchn_unmask_t           unmask;
 320     } u;
 321 };
 322 typedef struct evtchn_op evtchn_op_t;
 323 DEFINE_XEN_GUEST_HANDLE(evtchn_op_t);
 324
 325 /*
 326  * 2-level ABI
 327  */
 328
 329 #define EVTCHN_2L_NR_CHANNELS (sizeof(xen_ulong_t) * sizeof(xen_ulong_t) * 64)
 330
 331 /*
 332  * FIFO ABI
 333  */
 334
 335 /* Events may have priorities from 0 (highest) to 15 (lowest). */
 336 #define EVTCHN_FIFO_PRIORITY_MAX     0
 337 #define EVTCHN_FIFO_PRIORITY_DEFAULT 7
 338 #define EVTCHN_FIFO_PRIORITY_MIN     15
 339
 340 #define EVTCHN_FIFO_MAX_QUEUES (EVTCHN_FIFO_PRIORITY_MIN + 1)
 341
 342 typedef uint32_t event_word_t;
 343
 344 #define EVTCHN_FIFO_PENDING 31
 345 #define EVTCHN_FIFO_MASKED  30
 346 #define EVTCHN_FIFO_LINKED  29
 347 #define EVTCHN_FIFO_BUSY    28
 348
 349 #define EVTCHN_FIFO_LINK_BITS 17
 350 #define EVTCHN_FIFO_LINK_MASK ((1 << EVTCHN_FIFO_LINK_BITS) - 1)
 351
 352 #define EVTCHN_FIFO_NR_CHANNELS (1 << EVTCHN_FIFO_LINK_BITS)
 353
 354 struct evtchn_fifo_control_block {
 355     uint32_t ready;
 356     uint32_t _rsvd;
 357     uint32_t head[EVTCHN_FIFO_MAX_QUEUES];
 358 };
 359 typedef struct evtchn_fifo_control_block evtchn_fifo_control_block_t;
 360
 361 #endif /* __XEN_PUBLIC_EVENT_CHANNEL_H__ */
 362
 363 /*
 364  * Local variables:
 365  * mode: C
 366  * c-file-style: "BSD"
 367  * c-basic-offset: 4
 368  * tab-width: 4
 369  * indent-tabs-mode: nil
 370  * End:
 371  */