[Qemu-devel] Re: [PATCH] optionally specify vm stop message

[Jan Kiszka <jan.kiszka@siemens.com>]

Jan Kiszka wrote:
> Jan Kiszka wrote:
>> Anthony Liguori wrote:
>>> Jan Kiszka wrote:
>>>> Anthony Liguori wrote:
>>>>  
>>>>>>  Also non zero reasons a handled differently by vm_stop. Don't know
>>>>>> why.
>>>>>>         
>>>>> It's an ugly hack for gdbstub.  It notifies gdb when a breakpoint
>>>>> occurs.  We have far too many state tracking mechanisms.  Anyway, gdb
>>>>> can pass something like VM_STOP_BP and that can be used to trigger the
>>>>> callback.
>>>>>     
>>>> It's not only used for breakpoints but any stop condition that should be
>>>> reported to the gdb frontend (so far: EXCP_DEBUG and EXCP_INTERRUPT).
>>>> Not sure, though, how to deal with ENOSPC - it's not a guest fault, it's
>>>> a host problem. From that POV, gdb should not receive it.
>>>>   
>>> We already have a vm_change_state_handler that is invoked whenever a
>>> guest starts running or stops running.  gdb should be able to use that
>>> and look at env->exception_index, no?
>> I don't think env->exception_index is set when you issue "stop" from the
>> monitor, e.g. Moreover, that would be an ugly (out-of-band) API as well.
>>
> 
> The point is that vm_stop can be issued from any context, not just from
> a vcpu. So there may be no env channel at this point.

But we could enhance the state-change callback interface.... WARNING,
untested quick-hack to overcome vm_stop_cb follows!

Jan

-------->

diff --git a/audio/audio.c b/audio/audio.c
index 762c2e3..e2635c0 100644
--- a/audio/audio.c
+++ b/audio/audio.c
@@ -1622,7 +1622,8 @@ static int audio_driver_init (AudioState *s, struct audio_driver *drv)
     }
 }
 
-static void audio_vm_change_state_handler (void *opaque, int running)
+static void audio_vm_change_state_handler (void *opaque, int running,
+                                           int reason)
 {
     AudioState *s = opaque;
     HWVoiceOut *hwo = NULL;
diff --git a/gdbstub.c b/gdbstub.c
index 6db6d22..984acbd 100644
--- a/gdbstub.c
+++ b/gdbstub.c
@@ -1991,7 +1991,7 @@ void gdb_set_stop_cpu(CPUState *env)
 }
 
 #ifndef CONFIG_USER_ONLY
-static void gdb_vm_stopped(void *opaque, int reason)
+static void gdb_vm_state_change(void *opaque, int running, int reason)
 {
     GDBState *s = gdbserver_state;
     CPUState *env = s->c_cpu;
@@ -1999,7 +1999,8 @@ static void gdb_vm_stopped(void *opaque, int reason)
     const char *type;
     int ret;
 
-    if (s->state == RS_SYSCALL)
+    if (running || (reason != EXCP_DEBUG && reason != EXCP_INTERRUPT) ||
+        s->state == RS_SYSCALL)
         return;
 
     /* disable single step if it was enable */
@@ -2028,10 +2029,8 @@ static void gdb_vm_stopped(void *opaque, int reason)
         }
 	tb_flush(env);
         ret = GDB_SIGNAL_TRAP;
-    } else if (reason == EXCP_INTERRUPT) {
-        ret = GDB_SIGNAL_INT;
     } else {
-        ret = 0;
+        ret = GDB_SIGNAL_INT;
     }
     snprintf(buf, sizeof(buf), "T%02xthread:%02x;", ret, env->cpu_index+1);
     put_packet(s, buf);
@@ -2424,7 +2423,7 @@ int gdbserver_start(const char *port)
     gdbserver_state = s;
     qemu_chr_add_handlers(chr, gdb_chr_can_receive, gdb_chr_receive,
                           gdb_chr_event, NULL);
-    qemu_add_vm_stop_handler(gdb_vm_stopped, NULL);
+    qemu_add_vm_change_state_handler(gdb_vm_state_change, NULL);
     return 0;
 }
 #endif
diff --git a/sysemu.h b/sysemu.h
index 55f8d79..d8df642 100644
--- a/sysemu.h
+++ b/sysemu.h
@@ -12,16 +12,12 @@ extern uint8_t qemu_uuid[];
 #define UUID_FMT "%02hhx%02hhx%02hhx%02hhx-%02hhx%02hhx-%02hhx%02hhx-%02hhx%02hhx-%02hhx%02hhx%02hhx%02hhx%02hhx%02hhx"
 
 typedef struct vm_change_state_entry VMChangeStateEntry;
-typedef void VMChangeStateHandler(void *opaque, int running);
-typedef void VMStopHandler(void *opaque, int reason);
+typedef void VMChangeStateHandler(void *opaque, int running, int reason);
 
 VMChangeStateEntry *qemu_add_vm_change_state_handler(VMChangeStateHandler *cb,
                                                      void *opaque);
 void qemu_del_vm_change_state_handler(VMChangeStateEntry *e);
 
-int qemu_add_vm_stop_handler(VMStopHandler *cb, void *opaque);
-void qemu_del_vm_stop_handler(VMStopHandler *cb, void *opaque);
-
 void vm_start(void);
 void vm_stop(int reason);
 
diff --git a/vl.c b/vl.c
index be6819d..5192303 100644
--- a/vl.c
+++ b/vl.c
@@ -3404,37 +3404,21 @@ void qemu_del_vm_change_state_handler(VMChangeStateEntry *e)
     qemu_free (e);
 }
 
-static void vm_state_notify(int running)
+static void vm_state_notify(int running, int reason)
 {
     VMChangeStateEntry *e;
 
     for (e = vm_change_state_head.lh_first; e; e = e->entries.le_next) {
-        e->cb(e->opaque, running);
+        e->cb(e->opaque, running, reason);
     }
 }
 
-/* XXX: support several handlers */
-static VMStopHandler *vm_stop_cb;
-static void *vm_stop_opaque;
-
-int qemu_add_vm_stop_handler(VMStopHandler *cb, void *opaque)
-{
-    vm_stop_cb = cb;
-    vm_stop_opaque = opaque;
-    return 0;
-}
-
-void qemu_del_vm_stop_handler(VMStopHandler *cb, void *opaque)
-{
-    vm_stop_cb = NULL;
-}
-
 void vm_start(void)
 {
     if (!vm_running) {
         cpu_enable_ticks();
         vm_running = 1;
-        vm_state_notify(1);
+        vm_state_notify(1, 0);
         qemu_rearm_alarm_timer(alarm_timer);
     }
 }
@@ -3444,12 +3428,7 @@ void vm_stop(int reason)
     if (vm_running) {
         cpu_disable_ticks();
         vm_running = 0;
-        if (reason != 0) {
-            if (vm_stop_cb) {
-                vm_stop_cb(vm_stop_opaque, reason);
-            }
-        }
-        vm_state_notify(0);
+        vm_state_notify(0, reason);
     }
 }
 
-- 
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