[RFC PATCH v3 26/38] hw/xen: Implement EVTCHNOP_close

[David Woodhouse <dwmw2@infradead.org>]

From: David Woodhouse <dwmw@amazon.co.uk>

It calls an internal close_port() helper which will also be used from
EVTCHNOP_reset and will actually do the work to disconnect/unbind a port
once any of that is actually implemented in the first place.

That in turn calls a free_port() internal function which will be in
error paths after allocation.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
 hw/i386/kvm/xen_evtchn.c  | 51 +++++++++++++++++++++++++++++++++++++++
 hw/i386/kvm/xen_evtchn.h  |  2 ++
 target/i386/kvm/xen-emu.c | 12 +++++++++
 3 files changed, 65 insertions(+)

diff --git a/hw/i386/kvm/xen_evtchn.c b/hw/i386/kvm/xen_evtchn.c
index 77acf58540..d4008e7ee1 100644
--- a/hw/i386/kvm/xen_evtchn.c
+++ b/hw/i386/kvm/xen_evtchn.c
@@ -221,3 +221,54 @@ int xen_evtchn_status_op(struct evtchn_status *status)
     qemu_mutex_unlock(&s->port_lock);
     return 0;
 }
+
+static void free_port(XenEvtchnState *s, evtchn_port_t port)
+{
+    s->port_table[port].type = EVTCHNSTAT_closed;
+    s->port_table[port].type_val = 0;
+    s->port_table[port].vcpu = 0;
+
+    if (s->nr_ports == port + 1) {
+        do {
+            s->nr_ports--;
+        } while (s->port_table[s->nr_ports - 1].type == EVTCHNSTAT_closed);
+    }
+}
+
+static int close_port(XenEvtchnState *s, evtchn_port_t port)
+{
+    XenEvtchnPort *p = &s->port_table[port];
+
+    switch (p->type) {
+    case EVTCHNSTAT_closed:
+        return -ENOENT;
+
+    default:
+        break;
+    }
+
+    free_port(s, port);
+    return 0;
+}
+
+int xen_evtchn_close_op(struct evtchn_close *close)
+{
+    XenEvtchnState *s = xen_evtchn_singleton;
+    int ret;
+
+    if (!s) {
+        return -ENOTSUP;
+    }
+
+    if (!valid_port(close->port)) {
+        return -EINVAL;
+    }
+
+    qemu_mutex_lock(&s->port_lock);
+
+    ret = close_port(s, close->port);
+
+    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 6f50e5c52d..4c00000315 100644
--- a/hw/i386/kvm/xen_evtchn.h
+++ b/hw/i386/kvm/xen_evtchn.h
@@ -14,4 +14,6 @@ void xen_evtchn_create(void);
 int xen_evtchn_set_callback_param(uint64_t param);
 
 struct evtchn_status;
+struct evtchn_close;
 int xen_evtchn_status_op(struct evtchn_status *status);
+int xen_evtchn_close_op(struct evtchn_close *close);
diff --git a/target/i386/kvm/xen-emu.c b/target/i386/kvm/xen-emu.c
index d4a35bef64..f57d99f9d6 100644
--- a/target/i386/kvm/xen-emu.c
+++ b/target/i386/kvm/xen-emu.c
@@ -640,6 +640,18 @@ static bool kvm_xen_hcall_evtchn_op(struct kvm_xen_exit *exit, X86CPU *cpu,
         }
         break;
     }
+    case EVTCHNOP_close: {
+        struct evtchn_close close;
+
+        qemu_build_assert(sizeof(close) == 4);
+        if (kvm_copy_from_gva(cs, arg, &close, sizeof(close))) {
+            err = -EFAULT;
+            break;
+        }
+
+        err = xen_evtchn_close_op(&close);
+        break;
+    }
     default:
         return false;
     }
-- 
2.35.3