[RFC PATCH v1 17/26] kvm: vmi: add 'unhook_timeout' property

["Adalbert Lazăr" <alazar@bitdefender.com>]

When the introspection tool has to remove all changes made to the
introspected VM, the guest must run because some hooks can be removed only
in certain conditions. But this shouldn't take too long even with a host
under heavy load. So, if the socket is not closed by the introspection
tool at the end of this unhook process in the time specified by the
unhook_timeout property, QEMU will shutdown the socket.

Signed-off-by: Adalbert Lazăr <alazar@bitdefender.com>
---
 accel/kvm/vmi.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/accel/kvm/vmi.c b/accel/kvm/vmi.c
index 151e27265a..1f3aff3bfe 100644
--- a/accel/kvm/vmi.c
+++ b/accel/kvm/vmi.c
@@ -25,6 +25,7 @@
 #include "sysemu/vmi-handshake.h"
 
 #define HANDSHAKE_TIMEOUT_SEC 10
+#define UNHOOK_TIMEOUT_SEC 60
 
 typedef struct VMIntrospection {
     Object parent_obj;
@@ -48,6 +49,8 @@ typedef struct VMIntrospection {
     uint32_t handshake_timeout;
 
     int intercepted_action;
+    GSource *unhook_timer;
+    uint32_t unhook_timeout;
 
     int reconnect_time;
 
@@ -219,6 +222,11 @@ static void instance_init(Object *obj)
     object_property_add(obj, "handshake_timeout", "uint32",
                         prop_set_uint32, prop_get_uint32,
                         NULL, &i->handshake_timeout, NULL);
+
+    i->unhook_timeout = UNHOOK_TIMEOUT_SEC;
+    object_property_add(obj, "unhook_timeout", "uint32",
+                        prop_set_uint32, prop_get_uint32,
+                        NULL, &i->unhook_timeout, NULL);
 }
 
 static void disconnect_chardev(VMIntrospection *i)
@@ -269,6 +277,12 @@ static void cancel_handshake_timer(VMIntrospection *i)
     i->hsk_timer = NULL;
 }
 
+static void cancel_unhook_timer(VMIntrospection *i)
+{
+    cancel_timer(i->unhook_timer);
+    i->unhook_timer = NULL;
+}
+
 static void instance_finalize(Object *obj)
 {
     VMIntrospectionClass *ic = VM_INTROSPECTION_CLASS(obj->class);
@@ -277,6 +291,7 @@ static void instance_finalize(Object *obj)
     g_free(i->chardevid);
     g_free(i->keyid);
 
+    cancel_unhook_timer(i);
     cancel_handshake_timer(i);
 
     if (i->chr) {
@@ -576,6 +591,7 @@ static void chr_event_close(VMIntrospection *i)
         disconnect_and_unhook_kvmi(i);
     }
 
+    cancel_unhook_timer(i);
     cancel_handshake_timer(i);
 
     if (suspend_pending) {
@@ -604,6 +620,19 @@ static void chr_event(void *opaque, QEMUChrEvent event)
     }
 }
 
+static gboolean unhook_timeout_cbk(gpointer opaque)
+{
+    VMIntrospection *i = opaque;
+
+    warn_report("VMI: the introspection tool is too slow");
+
+    g_source_unref(i->unhook_timer);
+    i->unhook_timer = NULL;
+
+    disconnect_and_unhook_kvmi(i);
+    return FALSE;
+}
+
 static VMIntrospection *vm_introspection_object(void)
 {
     VMIntrospectionClass *ic;
@@ -663,6 +692,10 @@ static bool intercept_action(VMIntrospection *i,
         return false;
     }
 
+    i->unhook_timer = qemu_chr_timeout_add_ms(i->chr,
+                                              i->unhook_timeout * 1000,
+                                              unhook_timeout_cbk, i);
+
     i->intercepted_action = action;
     return true;
 }