From f5417856d25f1cf4932ac77a687979af8427f313 Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw@amazon.co.uk>
Date: Tue, 13 Dec 2022 23:12:59 +0000
Subject: [PATCH] hw/xen: Implement EVTCHNOP_bind_ipi

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
---
 hw/i386/kvm/xen_evtchn.c  | 69 +++++++++++++++++++++++++++++++++++++++
 hw/i386/kvm/xen_evtchn.h  |  2 ++
 target/i386/kvm/xen-emu.c | 15 +++++++++
 3 files changed, 86 insertions(+)

diff --git a/hw/i386/kvm/xen_evtchn.c b/hw/i386/kvm/xen_evtchn.c
index a3202d39ab..eea80dc0f5 100644
--- a/hw/i386/kvm/xen_evtchn.c
+++ b/hw/i386/kvm/xen_evtchn.c
@@ -13,6 +13,7 @@
 #include "qemu/host-utils.h"
 #include "qemu/module.h"
 #include "qemu/main-loop.h"
+#include "qemu/log.h"
 #include "qapi/error.h"
 #include "qom/object.h"
 #include "exec/target_page.h"
@@ -231,6 +232,43 @@ static void inject_callback(XenEvtchnState *s, uint32_t vcpu)
     kvm_xen_inject_vcpu_callback_vector(vcpu, type);
 }
 
+static void deassign_kernel_port(evtchn_port_t port)
+{
+    struct kvm_xen_hvm_attr ha;
+    int ret;
+
+    ha.type = KVM_XEN_ATTR_TYPE_EVTCHN;
+    ha.u.evtchn.send_port = port;
+    ha.u.evtchn.flags = KVM_XEN_EVTCHN_DEASSIGN;
+
+    ret = kvm_vm_ioctl(kvm_state, KVM_XEN_HVM_SET_ATTR, &ha);
+    if (ret) {
+        qemu_log_mask(LOG_GUEST_ERROR, "Failed to unbind kernel port %d: %s\n",
+                      port, strerror(ret));
+    }
+}
+
+static int assign_kernel_port(uint16_t type, evtchn_port_t port,
+                              uint32_t vcpu_id)
+{
+    CPUState *cpu = qemu_get_cpu(vcpu_id);
+    struct kvm_xen_hvm_attr ha;
+
+    if (!cpu) {
+        return -ENOENT;
+    }
+
+    ha.type = KVM_XEN_ATTR_TYPE_EVTCHN;
+    ha.u.evtchn.send_port = port;
+    ha.u.evtchn.type = type;
+    ha.u.evtchn.flags = 0;
+    ha.u.evtchn.deliver.port.port = port;
+    ha.u.evtchn.deliver.port.vcpu = kvm_arch_vcpu_id(cpu);
+    ha.u.evtchn.deliver.port.priority = KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL;
+
+    return kvm_vm_ioctl(kvm_state, KVM_XEN_HVM_SET_ATTR, &ha);
+}
+
 static bool valid_port(evtchn_port_t port)
 {
     if (!port) {
@@ -551,6 +589,12 @@ static int close_port(XenEvtchnState *s, evtchn_port_t port)
                               p->type_val, 0);
         break;
 
+    case EVTCHNSTAT_ipi:
+        if (s->evtchn_in_kernel) {
+            deassign_kernel_port(port);
+        }
+        break;
+
     default:
         break;
     }
@@ -640,3 +684,28 @@ int xen_evtchn_bind_virq_op(struct evtchn_bind_virq *virq)
 
     return ret;
 }
+
+int xen_evtchn_bind_ipi_op(struct evtchn_bind_ipi *ipi)
+{
+    XenEvtchnState *s = xen_evtchn_singleton;
+    int ret;
+
+    if (!s) {
+        return -ENOTSUP;
+    }
+
+    if (!valid_vcpu(ipi->vcpu)) {
+        return -ENOENT;
+    }
+
+    qemu_mutex_lock(&s->port_lock);
+
+    ret = allocate_port(s, ipi->vcpu, EVTCHNSTAT_ipi, 0, &ipi->port);
+    if (!ret && s->evtchn_in_kernel) {
+        assign_kernel_port(EVTCHNSTAT_ipi, ipi->port, ipi->vcpu);
+    }
+
+    qemu_mutex_unlock(&s->port_lock);
+
+    return ret;
+}
diff --git a/hw/i386/kvm/xen_evtchn.h b/hw/i386/kvm/xen_evtchn.h
index 0ea13dda3a..107f420848 100644
--- a/hw/i386/kvm/xen_evtchn.h
+++ b/hw/i386/kvm/xen_evtchn.h
@@ -19,9 +19,11 @@ struct evtchn_status;
 struct evtchn_close;
 struct evtchn_unmask;
 struct evtchn_bind_virq;
+struct evtchn_bind_ipi;
 int xen_evtchn_status_op(struct evtchn_status *status);
 int xen_evtchn_close_op(struct evtchn_close *close);
 int xen_evtchn_unmask_op(struct evtchn_unmask *unmask);
 int xen_evtchn_bind_virq_op(struct evtchn_bind_virq *virq);
+int xen_evtchn_bind_ipi_op(struct evtchn_bind_ipi *ipi);
 
 #endif /* QEMU_XEN_EVTCHN_H */
diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c
index e0417f3d13..b8b439dd31 100644
--- a/target/i386/kvm/xen-emu.c
+++ b/target/i386/kvm/xen-emu.c
@@ -894,6 +894,21 @@ static bool kvm_xen_hcall_evtchn_op(struct kvm_xen_exit *exit, X86CPU *cpu,
         }
         break;
     }
+    case EVTCHNOP_bind_ipi: {
+        struct evtchn_bind_ipi ipi;
+
+        qemu_build_assert(sizeof(ipi) == 8);
+        if (kvm_copy_from_gva(cs, arg, &ipi, sizeof(ipi))) {
+            err = -EFAULT;
+            break;
+        }
+
+        err = xen_evtchn_bind_ipi_op(&ipi);
+        if (!err && kvm_copy_to_gva(cs, arg, &ipi, sizeof(ipi))) {
+            err = -EFAULT;
+        }
+        break;
+    }
     default:
         return false;
     }