From 8432788104b6b4843738edbc5cf084b2a3687ee9 Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw@amazon.co.uk>
Date: Wed, 14 Dec 2022 17:26:32 +0000
Subject: [PATCH] hw/xen: Implement EVTCHNOP_bind_interdomain

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
---
 hw/i386/kvm/xen_evtchn.c  | 78 +++++++++++++++++++++++++++++++++++++++++++++++
 hw/i386/kvm/xen_evtchn.h  |  2 ++
 target/i386/kvm/xen-emu.c | 16 ++++++++++
 3 files changed, 96 insertions(+)

diff --git a/hw/i386/kvm/xen_evtchn.c b/hw/i386/kvm/xen_evtchn.c
index df25bf0806..e2e36d94f6 100644
--- a/hw/i386/kvm/xen_evtchn.c
+++ b/hw/i386/kvm/xen_evtchn.c
@@ -722,6 +722,23 @@ static int close_port(XenEvtchnState *s, evtchn_port_t port)
         }
         break;
 
+    case EVTCHNSTAT_interdomain:
+        if (p->type_val & PORT_INFO_TYPEVAL_REMOTE_QEMU) {
+            /* Not yet implemented. This can't happen! */
+        } else {
+            /* Loopback interdomain */
+            XenEvtchnPort *rp = &s->port_table[p->type_val];
+            if (!valid_port(p->type_val) || rp->type_val != port ||
+                rp->type != EVTCHNSTAT_interdomain) {
+                error_report("Inconsistent state for interdomain unbind");
+            } else {
+                /* Set the other end back to unbound */
+                rp->type = EVTCHNSTAT_unbound;
+                rp->type_val = 0;
+            }
+        }
+        break;
+
     default:
         break;
     }
@@ -837,6 +854,67 @@ int xen_evtchn_bind_ipi_op(struct evtchn_bind_ipi *ipi)
     return ret;
 }
 
+int xen_evtchn_bind_interdomain_op(struct evtchn_bind_interdomain *interdomain)
+{
+    XenEvtchnState *s = xen_evtchn_singleton;
+    uint16_t type_val;
+    int ret;
+
+    if (!s) {
+        return -ENOTSUP;
+    }
+
+    if (interdomain->remote_dom == DOMID_QEMU) {
+        type_val = PORT_INFO_TYPEVAL_REMOTE_QEMU;
+    } else if (interdomain->remote_dom == DOMID_SELF ||
+               interdomain->remote_dom == xen_domid) {
+        type_val = 0;
+    } else {
+        return -ESRCH;
+    }
+
+    if (!valid_port(interdomain->remote_port)) {
+        return -EINVAL;
+    }
+
+    qemu_mutex_lock(&s->port_lock);
+
+    /* The newly allocated port starts out as unbound */
+    ret = allocate_port(s, 0, EVTCHNSTAT_unbound, type_val,
+                        &interdomain->local_port);
+    if (ret) {
+        goto out;
+    }
+
+    if (interdomain->remote_dom == DOMID_QEMU) {
+        /* We haven't hooked up QEMU's PV drivers to this yet */
+        ret = -ENOSYS;
+    } else {
+        /* Loopback */
+        XenEvtchnPort *rp = &s->port_table[interdomain->remote_port];
+        XenEvtchnPort *lp = &s->port_table[interdomain->local_port];
+
+        if (rp->type == EVTCHNSTAT_unbound && rp->type_val == 0) {
+            /* It's a match! */
+            rp->type = EVTCHNSTAT_interdomain;
+            rp->type_val = interdomain->local_port;
+
+            lp->type = EVTCHNSTAT_interdomain;
+            lp->type_val = interdomain->remote_port;
+        } else {
+            ret = -EINVAL;
+        }
+    }
+
+    if (ret) {
+        free_port(s, interdomain->local_port);
+    }
+ out:
+    qemu_mutex_unlock(&s->port_lock);
+
+    return ret;
+
+}
 int xen_evtchn_alloc_unbound_op(struct evtchn_alloc_unbound *alloc)
 {
     XenEvtchnState *s = xen_evtchn_singleton;
diff --git a/hw/i386/kvm/xen_evtchn.h b/hw/i386/kvm/xen_evtchn.h
index fc080138e3..1ebc7580eb 100644
--- a/hw/i386/kvm/xen_evtchn.h
+++ b/hw/i386/kvm/xen_evtchn.h
@@ -22,6 +22,7 @@ struct evtchn_bind_virq;
 struct evtchn_bind_ipi;
 struct evtchn_send;
 struct evtchn_alloc_unbound;
+struct evtchn_bind_interdomain;
 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);
@@ -29,5 +30,6 @@ int xen_evtchn_bind_virq_op(struct evtchn_bind_virq *virq);
 int xen_evtchn_bind_ipi_op(struct evtchn_bind_ipi *ipi);
 int xen_evtchn_send_op(struct evtchn_send *send);
 int xen_evtchn_alloc_unbound_op(struct evtchn_alloc_unbound *alloc);
+int xen_evtchn_bind_interdomain_op(struct evtchn_bind_interdomain *interdomain);
 
 #endif /* QEMU_XEN_EVTCHN_H */
diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c
index ac04387a6a..1aff6b1042 100644
--- a/target/i386/kvm/xen-emu.c
+++ b/target/i386/kvm/xen-emu.c
@@ -936,6 +936,22 @@ static bool kvm_xen_hcall_evtchn_op(struct kvm_xen_exit *exit, X86CPU *cpu,
         }
         break;
     }
+    case EVTCHNOP_bind_interdomain: {
+        struct evtchn_bind_interdomain interdomain;
+
+        qemu_build_assert(sizeof(interdomain) == 12);
+        if (kvm_copy_from_gva(cs, arg, &interdomain, sizeof(interdomain))) {
+            err = -EFAULT;
+            break;
+        }
+
+        err = xen_evtchn_bind_interdomain_op(&interdomain);
+        if (!err &&
+            kvm_copy_to_gva(cs, arg, &interdomain, sizeof(interdomain))) {
+            err = -EFAULT;
+        }
+        break;
+    }
     default:
         return false;
     }
-- 
2.11.0