函数调用： Ø 初始化__start_xen() domain_create() // 这里是创建dom0 evtchn_init() // 初始化 get_free_port() Ø 操作相关操作都通过hypercall HYPERVISOR_event_channel_op(int cmd, void *arg)来进行。arg根据cmd的不同而不同。例如：#define EVTCHNOP_send 4struct evtchn_send { /* IN parameters. */ evtchn_port_t port;};typedef struct evtchn_send evtchn_send_t;被保存在struct evtchn_op中。 所有的操作的服务例程都是：long do_event_channel_op(int cmd, XEN_GUEST_HANDLE(void) arg){ long rc; switch ( cmd ) { case EVTCHNOP_alloc_unbound: {域间绑定有两个过程：EVTCHNOP_alloc_unbound + EVTCHNOP_bind_interdomain 为指定的dom分配一个port，供remote_dom来进行域间绑定。Allocate a port in domain <dom> and mark as accepting interdomain bindings from domain <remote_dom>. struct evtchn_alloc_unbound alloc_unbound; if ( copy_from_guest(&alloc_unbound, arg, 1) != 0 ) // 调用此函数的时候，struct alloc_unbound return -EFAULT; // domid_t dom, remote_dom;已经准备好 rc = evtchn_alloc_unbound(&alloc_unbound); if ( (rc == 0) && (copy_to_guest(arg, &alloc_unbound, 1) != 0) ) rc = -EFAULT; /* Cleaning up here would be a mess! */ break; } case EVTCHNOP_bind_interdomain: {和指定的远程dom/port建立连接，返回连接的本地port。<remote_dom,remote_port> must identify a port that is unbound and marked as accepting bindings from the calling domain. struct evtchn_bind_interdomain bind_interdomain; if ( copy_from_guest(&bind_interdomain, arg, 1) != 0 ) return -EFAULT; rc = evtchn_bind_interdomain(&bind_interdomain); // 调用时，remote dom/port已经设置好 if ( (rc == 0) && (copy_to_guest(arg, &bind_interdomain, 1) != 0) ) rc = -EFAULT; /* Cleaning up here would be a mess! */ break; } case EVTCHNOP_bind_virq: {绑定指定的VIRQ到指定的VCPU。 struct evtchn_bind_virq bind_virq; if ( copy_from_guest(&bind_virq, arg, 1) != 0 ) return -EFAULT; rc = evtchn_bind_virq(&bind_virq); if ( (rc == 0) && (copy_to_guest(arg, &bind_virq, 1) != 0) ) rc = -EFAULT; /* Cleaning up here would be a mess! */ break; } case EVTCHNOP_bind_ipi: {当前dom的VCPU之间的通信。 struct evtchn_bind_ipi bind_ipi; if ( copy_from_guest(&bind_ipi, arg, 1) != 0 ) return -EFAULT; rc = evtchn_bind_ipi(&bind_ipi); if ( (rc == 0) && (copy_to_guest(arg, &bind_ipi, 1) != 0) ) rc = -EFAULT; /* Cleaning up here would be a mess! */ break; } case EVTCHNOP_bind_pirq: {只有dom0和IDD才有权申请PIRQ。这些dom不能直接处理PIRQ，必须由Xen接受PIRQ，然后转发给dom处理。 struct evtchn_bind_pirq bind_pirq; if ( copy_from_guest(&bind_pirq, arg, 1) != 0 ) return -EFAULT; rc = evtchn_bind_pirq(&bind_pirq); if ( (rc == 0) && (copy_to_guest(arg, &bind_pirq, 1) != 0) ) rc = -EFAULT; /* Cleaning up here would be a mess! */ break; } case EVTCHNOP_close: {关闭当前dom的指定port。 struct evtchn_close close; if ( copy_from_guest(&close, arg, 1) != 0 ) return -EFAULT; rc = evtchn_close(&close); break; } case EVTCHNOP_send: {供域间通信和虚拟IPI之间使用。VIRQ和PIQR不需要使用，因为notification的发送方是Xen，不需要用hypercall。 struct evtchn_send send; if ( copy_from_guest(&send, arg, 1) != 0 ) return -EFAULT; rc = evtchn_send(current->domain, send.port); break; } case EVTCHNOP_status: {获得dom/port的状态信息。根据绑定类型（这里分为6类）的不同，返回的信息不同。 struct evtchn_status status; // 输入参数为dom/port，查询pair的状态 if ( copy_from_guest(&status, arg, 1) != 0 ) return -EFAULT; rc = evtchn_status(&status); if ( (rc == 0) && (copy_to_guest(arg, &status, 1) != 0) ) rc = -EFAULT; break; } case EVTCHNOP_bind_vcpu: {将指定的evtchn绑定到指定的VCPU处理。 struct evtchn_bind_vcpu bind_vcpu; if ( copy_from_guest(&bind_vcpu, arg, 1) != 0 ) return -EFAULT; rc = evtchn_bind_vcpu(bind_vcpu.port, bind_vcpu.vcpu); break; } case EVTCHNOP_unmask: {dom如何设置/取消mask参考mask_evtchn()/unmask_evtchn()。 struct evtchn_unmask unmask; if ( copy_from_guest(&unmask, arg, 1) != 0 ) return -EFAULT; rc = evtchn_unmask(unmask.port); break; } case EVTCHNOP_reset: {关闭指定dom的所有evtchn。 struct evtchn_reset reset; if ( copy_from_guest(&reset, arg, 1) != 0 ) return -EFAULT; rc = evtchn_reset(&reset); break; } default: rc = -ENOSYS; break; } return rc;} static long evtchn_status(evtchn_status_t *status){ struct domain *d; domid_t dom = status->dom; int port = status->port; // 被查询的dom/port struct evtchn *chn; long rc = 0; rc = rcu_lock_target_domain_by_id(dom, &d); if ( rc ) return rc; spin_lock(&d->event_lock); if ( !port_is_valid(d, port) ) { rc = -EINVAL; goto out; } chn = evtchn_from_port(d, port); // 获得对应的evtchn rc = xsm_evtchn_status(d, chn); if ( rc ) goto out; switch ( chn->state ) { case ECS_FREE: case ECS_RESERVED: status->status = EVTCHNSTAT_closed; break; case ECS_UNBOUND: status->status = EVTCHNSTAT_unbound; status->u.unbound.dom = chn->u.unbound.remote_domid; // 输出此dom/pair正开放给哪个远程dom break; case ECS_INTERDOMAIN: status->status = EVTCHNSTAT_interdomain; status->u.interdomain.dom = chn->u.interdomain.remote_dom->domain_id; status->u.interdomain.port = chn->u.interdomain.remote_port; // 输出对点的dom/port break; case ECS_PIRQ: status->status = EVTCHNSTAT_pirq; status->u.pirq = chn->u.pirq; break; case ECS_VIRQ: status->status = EVTCHNSTAT_virq; status->u.virq = chn->u.virq; break; case ECS_IPI: status->status = EVTCHNSTAT_ipi; break; default: BUG(); } status->vcpu = chn->notify_vcpu_id; out: spin_unlock(&d->event_lock); rcu_unlock_domain(d); return rc;} static long evtchn_alloc_unbound(evtchn_alloc_unbound_t *alloc){从指定的dom中获得一个free的evtchn(port)。分配给远端dom以后使用。如果是自己分配或分配给自己使用，则DOMID_SELF。然后1. 设置它的state和remote_domid。2. 填充获得的port进参数alloc。 分配的port被放入xenstore，以后想用的话，从中获得。方法是什么？ struct evtchn *chn; struct domain *d; int port; domid_t dom = alloc->dom; long rc; rc = rcu_lock_target_domain_by_id(dom, &d); if ( rc ) return rc; spin_lock(&d->event_lock); if ( (port = get_free_port(d)) < 0 ) // 从dom中获得一个free的port ERROR_EXIT_DOM(port, d); chn = evtchn_from_port(d, port); // 得到对应的struct evtchn rc = xsm_evtchn_unbound(d, chn, alloc->remote_dom); if ( rc ) goto out; chn->state = ECS_UNBOUND; // 设置(1)状态为ESC_UNBOUND if ( (chn->u.unbound.remote_domid = alloc->remote_dom) == DOMID_SELF ) chn->u.unbound.remote_domid = current->domain->domain_id; // 设置(2)remote_domid alloc->port = port; // 设置(3)到evtchn_alloc_unbound_t的port out: spin_unlock(&d->event_lock); rcu_unlock_domain(d); return rc;} static long evtchn_bind_interdomain(evtchn_bind_interdomain_t *bind)dom在调用hypercall的时候，已经将bind中remote_dom和remote_port设置好{ struct evtchn *lchn, *rchn; struct domain *ld = current->domain, *rd; int lport, rport = bind->remote_port; domid_t rdom = bind->remote_dom; long rc; if ( rdom == DOMID_SELF ) rdom = current->domain->domain_id; if ( (rd = rcu_lock_domain_by_id(rdom)) == NULL ) return -ESRCH; /* Avoid deadlock by first acquiring lock of domain with smaller id. */ if ( ld < rd ) { spin_lock(&ld->event_lock); spin_lock(&rd->event_lock); } else { if ( ld != rd ) spin_lock(&rd->event_lock); spin_lock(&ld->event_lock); } if ( (lport = get_free_port(ld)) < 0 ) // 获得一个本地的free port ERROR_EXIT(lport); lchn = evtchn_from_port(ld, lport); // 得到对应的本地evtchn if ( !port_is_valid(rd, rport) ) ERROR_EXIT_DOM(-EINVAL, rd); rchn = evtchn_from_port(rd, rport); // 根据rd和rport，获得远端evtchn if ( (rchn->state != ECS_UNBOUND) || // 远端evtchn的state要是ESC_UNBOUND (rchn->u.unbound.remote_domid != ld->domain_id) ) // 远端evtchn的remote domid要是自己的id ERROR_EXIT_DOM(-EINVAL, rd); // 这里就是要做的检查。即远端dom的port必须开放给了 // 自己。开放是在EVTCHNOP_alloc_unbound里面做的 rc = xsm_evtchn_interdomain(ld, lchn, rd, rchn); if ( rc ) goto out; lchn->u.interdomain.remote_dom = rd; lchn->u.interdomain.remote_port = (u16)rport; lchn->state = ECS_INTERDOMAIN; // 设置本地evtchn的状态 rchn->u.interdomain.remote_dom = ld; rchn->u.interdomain.remote_port = (u16)lport; rchn->state = ECS_INTERDOMAIN; // 设置远端evtchn的状态 /* * We may have lost notifications on the remote unbound port. Fix that up * here by conservatively always setting a notification on the local port. */ evtchn_set_pending(ld->vcpu[lchn->notify_vcpu_id], lport); // 设置本evtchn绑定的VCPU的pending位 // lchn里面的notify_vcpu_id是什么时候设置的 bind->local_port = lport; // 设置输出参数，本地port out: spin_unlock(&ld->event_lock); if ( ld != rd ) spin_unlock(&rd->event_lock); rcu_unlock_domain(rd); return rc;} static long evtchn_bind_virq(evtchn_bind_virq_t *bind){ struct evtchn *chn; struct vcpu *v; struct domain *d = current->domain; int port, virq = bind->virq, vcpu = bind->vcpu; long rc = 0; if ( (virq < 0) || (virq >= ARRAY_SIZE(v->virq_to_evtchn)) ) return -EINVAL; if ( virq_is_global(virq) && (vcpu != 0) ) // 全局型VIRQ只能绑定到VCPU0 return -EINVAL; if ( (vcpu < 0) || (vcpu >= d->max_vcpus) || ((v = d->vcpu[vcpu]) == NULL) ) // 根据VCPU的id，获得VCPU return -ENOENT; spin_lock(&d->event_lock); if ( v->virq_to_evtchn[virq] != 0 ) // 如果对应的port不为0 ERROR_EXIT(-EEXIST); if ( (port = get_free_port(d)) < 0 ) // 获得port ERROR_EXIT(port); chn = evtchn_from_port(d, port); // 获得对应的evtchn chn->state = ECS_VIRQ; // 设置state为ECS_VIRQ chn->notify_vcpu_id = vcpu; // 在evtchn中，设置绑定到的VCPU chn->u.virq = virq; // 设置绑定的VIRQ v->virq_to_evtchn[virq] = bind->port = port; // VIRQ绑定的port设置到vcpu的virq_to_evtchn // PIRQ设置到dom里面的pirq_to_evtchn out: spin_unlock(&d->event_lock); return rc;}static long evtchn_bind_ipi(evtchn_bind_ipi_t *bind){ struct evtchn *chn; struct domain *d = current->domain; // 当前dom int port, vcpu = bind->vcpu; long rc = 0; if ( (vcpu < 0) || (vcpu >= d->max_vcpus) || (d->vcpu[vcpu] == NULL) ) return -ENOENT; spin_lock(&d->event_lock); if ( (port = get_free_port(d)) < 0 ) // 获得一个port ERROR_EXIT(port); chn = evtchn_from_port(d, port); // 获得port对应的evtchn chn->state = ECS_IPI; chn->notify_vcpu_id = vcpu; // evtchn的IPI绑定，即设置此evtchn的notify_vcpu_id bind->port = port; // 设置输出参数 out: spin_unlock(&d->event_lock); return rc;}static long evtchn_bind_pirq(evtchn_bind_pirq_t *bind){ struct evtchn *chn; struct domain *d = current->domain; int port, pirq = bind->pirq; long rc; if ( (pirq < 0) || (pirq >= d->nr_pirqs) ) return -EINVAL; if ( !irq_access_permitted(d, pirq) ) return -EPERM; spin_lock(&d->event_lock); if ( d->pirq_to_evtchn[pirq] != 0 ) ERROR_EXIT(-EEXIST); if ( (port = get_free_port(d)) < 0 ) // 分配一个free的port ERROR_EXIT(port); chn = evtchn_from_port(d, port); // 获得对应的evtchn d->pirq_to_evtchn[pirq] = port; // PIRQ绑定的port设置到dom的pirq_to_evtchn rc = pirq_guest_bind(d->vcpu[0], pirq, !!(bind->flags & BIND_PIRQ__WILL_SHARE)); if ( rc != 0 ) { d->pirq_to_evtchn[pirq] = 0; goto out; } chn->state = ECS_PIRQ; chn->u.pirq = pirq; // PIRQ绑定 bind->port = port; // 设置输出参数 out: spin_unlock(&d->event_lock); return rc;}static long __evtchn_close(struct domain *d1, int port1){ struct domain *d2 = NULL; struct vcpu *v; struct evtchn *chn1, *chn2; int port2; long rc = 0; again: spin_lock(&d1->event_lock); if ( !port_is_valid(d1, port1) ) { rc = -EINVAL; goto out; } chn1 = evtchn_from_port(d1, port1); // 得到对应的evtchn /* Guest cannot close a Xen-attached event channel. */ if ( unlikely(chn1->consumer_is_xen) ) { rc = -EINVAL; goto out; } switch ( chn1->state ) { case ECS_FREE: case ECS_RESERVED: rc = -EINVAL; goto out; case ECS_UNBOUND: break; case ECS_PIRQ: pirq_guest_unbind(d1, chn1->u.pirq); d1->pirq_to_evtchn[chn1->u.pirq] = 0; break; case ECS_VIRQ: for_each_vcpu ( d1, v ) { if ( v->virq_to_evtchn[chn1->u.virq] != port1 ) continue; v->virq_to_evtchn[chn1->u.virq] = 0; spin_barrier_irq(&v->virq_lock); } break; case ECS_IPI: break; case ECS_INTERDOMAIN: if ( d2 == NULL ) { d2 = chn1->u.interdomain.remote_dom; /* If we unlock d1 then we could lose d2. Must get a reference. */ if ( unlikely(!get_domain(d2)) ) BUG(); if ( d1 < d2 ) { spin_lock(&d2->event_lock); } else if ( d1 != d2 ) { spin_unlock(&d1->event_lock); spin_lock(&d2->event_lock); goto again; } } else if ( d2 != chn1->u.interdomain.remote_dom ) { /* * We can only get here if the port was closed and re-bound after * unlocking d1 but before locking d2 above. We could retry but * it is easier to return the same error as if we had seen the * port in ECS_CLOSED. It must have passed through that state for * us to end up here, so it's a valid error to return. */ rc = -EINVAL; goto out; } port2 = chn1->u.interdomain.remote_port; // 获得远端port BUG_ON(!port_is_valid(d2, port2)); chn2 = evtchn_from_port(d2, port2); // 获得对应的evtchn BUG_ON(chn2->state != ECS_INTERDOMAIN); BUG_ON(chn2->u.interdomain.remote_dom != d1); chn2->state = ECS_UNBOUND; //设置远端为alloc之后，绑定之前的状态 chn2->u.unbound.remote_domid = d1->domain_id; // ECS_UNBOUND break; default: BUG(); } /* Clear pending event to avoid unexpected behavior on re-bind. */ clear_bit(port1, &shared_info(d1, evtchn_pending)); /* Reset binding to vcpu0 when the channel is freed. */ chn1->state = ECS_FREE; // 设置本地为ECS_FREE状态 chn1->notify_vcpu_id = 0; // 设置初始化状态绑定的VCPU为0 xsm_evtchn_close_post(chn1); out: if ( d2 != NULL ) { if ( d1 != d2 ) spin_unlock(&d2->event_lock); put_domain(d2); } spin_unlock(&d1->event_lock); return rc;} static long evtchn_close(evtchn_close_t *close){ return __evtchn_close(current->domain, close->port);}int evtchn_send(struct domain *d, unsigned int lport)d为本地dom。是current->domainlport为本地port，要send的对象{ struct evtchn *lchn, *rchn; struct domain *ld = d, *rd; struct vcpu *rvcpu; int rport, ret = 0; spin_lock(&ld->event_lock); if ( unlikely(!port_is_valid(ld, lport)) ) { spin_unlock(&ld->event_lock); return -EINVAL; } lchn = evtchn_from_port(ld, lport); // 首先获得lport对应的本地evtchn /* Guest cannot send via a Xen-attached event channel. */ if ( unlikely(lchn->consumer_is_xen) ) { spin_unlock(&ld->event_lock); return -EINVAL; } ret = xsm_evtchn_send(ld, lchn); if ( ret ) goto out; switch ( lchn->state ) { case ECS_INTERDOMAIN: // 域间通信 rd = lchn->u.interdomain.remote_dom; // 获得远端/对点的rdom rport = lchn->u.interdomain.remote_port; // 获得远端/对点的rport rchn = evtchn_from_port(rd, rport); // 获得rport对应的rchn rvcpu = rd->vcpu[rchn->notify_vcpu_id]; // 获得对点evtchn绑定的VCPU if ( rchn->consumer_is_xen ) { /* Xen consumers need notification only if they are blocked. */ if ( test_and_clear_bit(_VPF_blocked_in_xen, &rvcpu->pause_flags) ) vcpu_wake(rvcpu); } else { evtchn_set_pending(rvcpu, rport); // 设置对点VCPU上的port有event发生。 } // 下面将异步进行event句柄的处理。 break; case ECS_IPI: evtchn_set_pending(ld->vcpu[lchn->notify_vcpu_id], lport); // IPI的话，则设置对应的VCPU break; case ECS_UNBOUND: /* silently drop the notification */ break; default: // ESC_VIRQ & ESC_PIRQ不会到这里来 ret = -EINVAL; // 因为这些notification是的发送方是Xen，不需要用hypercall } out: spin_unlock(&ld->event_lock); return ret;}long evtchn_bind_vcpu(unsigned int port, unsigned int vcpu_id){绑定VCPU之后，这个event的处理就由该VCPU来完成。evtchn的屏蔽：1） 所有的VCPU屏蔽某个evtchn 设置evtchn的MASK位。这个MASK位在struct shared_info里面。2） 某个VCPU屏蔽所有evtchn 此VCPU结构体struct vcpu_info成员完成。方法在结构体处说明。 struct domain *d = current->domain; struct evtchn *chn; long rc = 0; if ( (vcpu_id >= d->max_vcpus) || (d->vcpu[vcpu_id] == NULL) ) return -ENOENT; spin_lock(&d->event_lock); if ( !port_is_valid(d, port) ) { rc = -EINVAL; goto out; } chn = evtchn_from_port(d, port); // 根据port得到evtchn /* Guest cannot re-bind a Xen-attached event channel. */ if ( unlikely(chn->consumer_is_xen) ) { rc = -EINVAL; goto out; } switch ( chn->state ) { case ECS_VIRQ: if ( virq_is_global(chn->u.virq) ) // 只有全局性虚拟中断才能绑定VCPU chn->notify_vcpu_id = vcpu_id; // 所谓绑定，不过是设置evtchn中的notify_vcpu_id else rc = -EINVAL; break; case ECS_UNBOUND: case ECS_INTERDOMAIN: // 域间绑定之后，状态会被设置为ECS_INTERDOMAIN。 case ECS_PIRQ: chn->notify_vcpu_id = vcpu_id; break; default: rc = -EINVAL; break; } out: spin_unlock(&d->event_lock); return rc;}int evtchn_unmask(unsigned int port){ struct domain *d = current->domain; struct vcpu *v; spin_lock(&d->event_lock); if ( unlikely(!port_is_valid(d, port)) ) { spin_unlock(&d->event_lock); return -EINVAL; } v = d->vcpu[evtchn_from_port(d, port)->notify_vcpu_id]; // 获得对应的VCPU /* * These operations must happen in strict order. Based on * include/xen/event.h:evtchn_set_pending(). */ if ( test_and_clear_bit(port, &shared_info(d, evtchn_mask)) && // 如果evtchn_mask被设置，那么取消设置（屏蔽） test_bit (port, &shared_info(d, evtchn_pending)) && // 并且evtchn_pending被设置（未决） !test_and_set_bit (port / BITS_PER_EVTCHN_WORD(d), // 那么设置此VCPU里的evtchn_pending_sel &vcpu_info(v, evtchn_pending_sel)) ) { vcpu_mark_events_pending(v); // 并且设置此VCPU里的evtchn_upcall_pending } spin_unlock(&d->event_lock); return 0;}static long evtchn_reset(evtchn_reset_t *r){ domid_t dom = r->dom; struct domain *d; int i, rc; rc = rcu_lock_target_domain_by_id(dom, &d); if ( rc ) return rc; rc = xsm_evtchn_reset(current->domain, d); if ( rc ) goto out; for ( i = 0; port_is_valid(d, i); i++ ) (void)__evtchn_close(d, i); // 可以这样做的原因是，当初分配port的时候就是严格按照顺序分配的 rc = 0; out: rcu_unlock_domain(d); return rc;}static int evtchn_set_pending(struct vcpu *v, int port){ struct domain *d = v->domain; // 通过VCPU找到对应的dom int vcpuid; /* * The following bit operations must happen in strict order. * NB. On x86, the atomic bit operations also act as memory barriers. * There is therefore sufficiently strict ordering for this architecture -- * others may require explicit memory barriers. */ if ( test_and_set_bit(port, &shared_info(d, evtchn_pending)) ) // 设置dom的shared_info里面 return 1; // evtchn_pending数组中对于元素的对应位（根据port）为1此evtchn的pending位都被置1。表明此evtchn需要/正在被某个VCPU处理。 if ( !test_bit (port, &shared_info(d, evtchn_mask)) && !test_and_set_bit(port / BITS_PER_EVTCHN_WORD(d), &vcpu_info(v, evtchn_pending_sel)) )如果此evtchn的mask位没有设置，则设置对应的VCPU的evtchn_pending_sel位（evtchn_pending_sel与evtchn_pending关联）。使该VCPU可以感知正在处理哪个event，即定位pending状态的evtchn。 { vcpu_mark_events_pending(v);同时，如果evtchn_pending_sel设置成功，则设置VCPU的evtchn_upcall_pending。表明本VCPU需要/正在处理event。 } /* Check if some VCPU might be polling for this event. */ if ( likely(bitmap_empty(d->poll_mask, d->max_vcpus)) ) return 0; /* Wake any interested (or potentially interested) pollers. */ for ( vcpuid = find_first_bit(d->poll_mask, d->max_vcpus); vcpuid < d->max_vcpus; vcpuid = find_next_bit(d->poll_mask, d->max_vcpus, vcpuid+1) ) { v = d->vcpu[vcpuid]; if ( ((v->poll_evtchn <= 0) || (v->poll_evtchn == port)) && test_and_clear_bit(vcpuid, d->poll_mask) ) { v->poll_evtchn = 0; vcpu_unblock(v); } } return 0;} #define shared_info(d, field) __shared_info(d, (d)->shared_info, field)#define __shared_info(d, s, field) ((s)->field) void vcpu_mark_events_pending(struct vcpu *v){ int already_pending = test_and_set_bit( 0, (unsigned long *)&vcpu_info(v, evtchn_upcall_pending)); if ( already_pending ) return; if ( is_hvm_vcpu(v) ) hvm_assert_evtchn_irq(v); else vcpu_kick(v);}void mask_evtchn(int port){ shared_info_t *s = HYPERVISOR_shared_info; // 获得shared_info synch_set_bit(port, s->evtchn_mask); // 设置里面的evtchn_mask}EXPORT_SYMBOL_GPL(mask_evtchn); void unmask_evtchn(int port){ shared_info_t *s = HYPERVISOR_shared_info; // 获得shared_info unsigned int cpu = smp_processor_id(); vcpu_info_t *vcpu_info = &s->vcpu_info[cpu]; // 获得当前的VCPU BUG_ON(!irqs_disabled()); /* Slow path (hypercall) if this is a non-local port. */ if (unlikely(cpu != cpu_from_evtchn(port))) { // 如果本evtchn没有绑定到本VCPU struct evtchn_unmask unmask = { .port = port }; VOID(HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask)); // hypercall处理 return; } synch_clear_bit(port, s->evtchn_mask); // 取消mask /* Did we miss an interrupt 'edge'? Re-fire if so. */ if (synch_test_bit(port, s->evtchn_pending) && // 如果存在未决evtchn !synch_test_and_set_bit(port / BITS_PER_LONG, &vcpu_info->evtchn_pending_sel)) vcpu_info->evtchn_upcall_pending = 1; // 设置VCPU的evtchn_upcall_pending}EXPORT_SYMBOL_GPL(unmask_evtchn);结构体：struct evtchn_op { uint32_t cmd; /* EVTCHNOP_* */ 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; struct shared_info { struct vcpu_info vcpu_info[XEN_LEGACY_MAX_VCPUS]; unsigned long evtchn_pending[sizeof(unsigned long) * 8]; // 32个long，有32*32=1024位 unsigned long evtchn_mask[sizeof(unsigned long) * 8]; uint32_t wc_version; /* Version counter: see vcpu_time_info_t. */ uint32_t wc_sec; /* Secs 00:00:00 UTC, Jan 1, 1970. */ uint32_t wc_nsec; /* Nsecs 00:00:00 UTC, Jan 1, 1970. */ struct arch_shared_info arch; } struct vcpu_info { uint8_t evtchn_upcall_pending; // 针对所有evtchn的 uint8_t evtchn_upcall_mask; // 设置为1，则此VCPU将屏蔽所有的evtchn。 unsigned long evtchn_pending_sel; // 每一位对应evtchn_pinding中一组32个evtchn。设置方法 struct arch_vcpu_info arch; struct vcpu_time_info time;}; /* 64 bytes (x86) */ /* * 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. <rdom> may be DOMID_SELF, allowing loopback connections. */#define EVTCHNOP_alloc_unbound 6struct evtchn_alloc_unbound { /* IN parameters */ domid_t dom, remote_dom; /* OUT parameters */ evtchn_port_t port; // 用于通信的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 // 参考EVTCHNOP_alloc_unbound * domain. A fresh port is allocated in the calling domain and returned as * <local_port>. * NOTES: * 2. <remote_dom> may be DOMID_SELF, allowing loopback connections. */#define EVTCHNOP_bind_interdomain 0struct 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. */#define EVTCHNOP_bind_virq 1struct evtchn_bind_virq { /* IN parameters. */ uint32_t 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 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. */#define EVTCHNOP_bind_pirq 2struct 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. */#define EVTCHNOP_bind_ipi 7struct 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. */#define EVTCHNOP_close 3struct 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>. */#define EVTCHNOP_send 4struct 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. */#define EVTCHNOP_status 5struct 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 */ // 如果是unbound状态，那么此port开放给哪个dom用 struct { domid_t dom; evtchn_port_t port; } interdomain; /* EVTCHNSTAT_interdomain */ // 如果是interdomain状态，那么连接的远程dom和port？ 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). */#define EVTCHNOP_bind_vcpu 8struct 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. */#define EVTCHNOP_unmask 9struct 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. */#define EVTCHNOP_reset 10struct evtchn_reset { /* IN parameters. */ domid_t dom;};typedef struct evtchn_reset evtchn_reset_t;
