From a15b10978fe62411936e577288f28184a41754a9 Mon Sep 17 00:00:00 2001
From: David Woodhouse <dwmw@amazon.co.uk>
Date: Wed, 14 Dec 2022 19:36:15 +0000
Subject: [PATCH] hw/xen: Implement EVTCHNOP_reset

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Paul Durrant <paul@xen.org>
---
 hw/i386/kvm/xen_evtchn.c  | 30 ++++++++++++++++++++++++++++++
 hw/i386/kvm/xen_evtchn.h  |  3 +++
 target/i386/kvm/xen-emu.c | 17 +++++++++++++++++
 3 files changed, 50 insertions(+)

diff --git a/hw/i386/kvm/xen_evtchn.c b/hw/i386/kvm/xen_evtchn.c
index cbaf4f535a..c804a315e0 100644
--- a/hw/i386/kvm/xen_evtchn.c
+++ b/hw/i386/kvm/xen_evtchn.c
@@ -12,6 +12,7 @@
 #include "qemu/osdep.h"
 #include "qemu/host-utils.h"
 #include "qemu/module.h"
+#include "qemu/lockable.h"
 #include "qemu/main-loop.h"
 #include "qemu/log.h"
 #include "qapi/error.h"
@@ -747,6 +748,35 @@ static int close_port(XenEvtchnState *s, evtchn_port_t port)
     return 0;
 }
 
+int xen_evtchn_soft_reset(void)
+{
+    XenEvtchnState *s = xen_evtchn_singleton;
+    int i;
+
+    if (!s) {
+        return -ENOTSUP;
+    }
+
+    assert(qemu_mutex_iothread_locked());
+
+    QEMU_LOCK_GUARD(&s->port_lock);
+
+    for (i = 0; i < s->nr_ports; i++) {
+        close_port(s, i);
+    }
+
+    return 0;
+}
+
+int xen_evtchn_reset_op(struct evtchn_reset *reset)
+{
+    if (reset->dom != DOMID_SELF && reset->dom != xen_domid) {
+        return -ESRCH;
+    }
+
+    return xen_evtchn_soft_reset();
+}
+
 int xen_evtchn_close_op(struct evtchn_close *close)
 {
     XenEvtchnState *s = xen_evtchn_singleton;
diff --git a/hw/i386/kvm/xen_evtchn.h b/hw/i386/kvm/xen_evtchn.h
index 486b031c82..5d3e03553f 100644
--- a/hw/i386/kvm/xen_evtchn.h
+++ b/hw/i386/kvm/xen_evtchn.h
@@ -13,6 +13,7 @@
 #define QEMU_XEN_EVTCHN_H
 
 void xen_evtchn_create(void);
+int xen_evtchn_soft_reset(void);
 int xen_evtchn_set_callback_param(uint64_t param);
 
 struct evtchn_status;
@@ -24,6 +25,7 @@ struct evtchn_send;
 struct evtchn_alloc_unbound;
 struct evtchn_bind_interdomain;
 struct evtchn_bind_vcpu;
+struct evtchn_reset;
 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);
@@ -33,5 +35,6 @@ 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);
 int xen_evtchn_bind_vcpu_op(struct evtchn_bind_vcpu *vcpu);
+int xen_evtchn_reset_op(struct evtchn_reset *reset);
 
 #endif /* QEMU_XEN_EVTCHN_H */
diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c
index 8dc0d320f5..821629f077 100644
--- a/target/i386/kvm/xen-emu.c
+++ b/target/i386/kvm/xen-emu.c
@@ -964,6 +964,18 @@ static bool kvm_xen_hcall_evtchn_op(struct kvm_xen_exit *exit, X86CPU *cpu,
         err = xen_evtchn_bind_vcpu_op(&vcpu);
         break;
     }
+    case EVTCHNOP_reset: {
+        struct evtchn_reset reset;
+
+        qemu_build_assert(sizeof(reset) == 2);
+        if (kvm_copy_from_gva(cs, arg, &reset, sizeof(reset))) {
+            err = -EFAULT;
+            break;
+        }
+
+        err = xen_evtchn_reset_op(&reset);
+        break;
+    }
     default:
         return false;
     }
@@ -981,6 +993,11 @@ int kvm_xen_soft_reset(void)
 
     trace_kvm_xen_soft_reset();
 
+    err = xen_evtchn_soft_reset();
+    if (err) {
+        return err;
+    }
+
     /*
      * Zero is the reset/startup state for HVM_PARAM_CALLBACK_IRQ. Strictly,
      * it maps to HVM_PARAM_CALLBACK_TYPE_GSI with GSI#0, but Xen refuses to