[Qemu-devel] [RFC v3 09/13] cpus.c: introduce simple callback support

[Alvise Rigo <a.rigo@virtualopensystems.com>]

In order to perfom "lazy" TLB invalidation requests, introduce a
queue of callbacks at every vCPU disposal that will be fired just
before entering the next TB.

Suggested-by: Jani Kokkonen <jani.kokkonen@huawei.com>
Suggested-by: Claudio Fontana <claudio.fontana@huawei.com>
Signed-off-by: Alvise Rigo <a.rigo@virtualopensystems.com>
---
 cpus.c            | 34 ++++++++++++++++++++++++++++++++++
 exec.c            |  1 +
 include/qom/cpu.h | 20 ++++++++++++++++++++
 3 files changed, 55 insertions(+)

diff --git a/cpus.c b/cpus.c
index f4d938e..b9f0329 100644
--- a/cpus.c
+++ b/cpus.c
@@ -1421,6 +1421,7 @@ static int tcg_cpu_exec(CPUArchState *env)
         cpu->icount_extra = count;
     }
     qemu_mutex_unlock_iothread();
+    cpu_exit_callbacks_call_all(cpu);
     ret = cpu_exec(env);
     cpu->tcg_executing = 0;
 
@@ -1469,6 +1470,39 @@ static void tcg_exec_all(CPUState *cpu)
     cpu->exit_request = 0;
 }
 
+void cpu_exit_callback_add(CPUState *cpu, CPUExitCallback callback,
+                           void *opaque)
+{
+    CPUExitCB *cb;
+
+    cb = g_malloc(sizeof(*cb));
+    cb->callback = callback;
+    cb->opaque = opaque;
+
+    qemu_mutex_lock(&cpu->exit_cbs.mutex);
+    QTAILQ_INSERT_TAIL(&cpu->exit_cbs.exit_callbacks, cb, entry);
+    qemu_mutex_unlock(&cpu->exit_cbs.mutex);
+}
+
+void cpu_exit_callbacks_call_all(CPUState *cpu)
+{
+    CPUExitCB *cb, *next;
+
+    if (QTAILQ_EMPTY(&cpu->exit_cbs.exit_callbacks)) {
+        return;
+    }
+
+    QTAILQ_FOREACH_SAFE(cb, &cpu->exit_cbs.exit_callbacks, entry, next) {
+        cb->callback(cpu, cb->opaque);
+
+        /* one-shot callbacks, remove it after using it */
+        qemu_mutex_lock(&cpu->exit_cbs.mutex);
+        QTAILQ_REMOVE(&cpu->exit_cbs.exit_callbacks, cb, entry);
+        g_free(cb);
+        qemu_mutex_unlock(&cpu->exit_cbs.mutex);
+    }
+}
+
 void list_cpus(FILE *f, fprintf_function cpu_fprintf, const char *optarg)
 {
     /* XXX: implement xxx_cpu_list for targets that still miss it */
diff --git a/exec.c b/exec.c
index 51958ed..322f2c6 100644
--- a/exec.c
+++ b/exec.c
@@ -531,6 +531,7 @@ void cpu_exec_init(CPUArchState *env)
     cpu->numa_node = 0;
     QTAILQ_INIT(&cpu->breakpoints);
     QTAILQ_INIT(&cpu->watchpoints);
+    QTAILQ_INIT(&cpu->exit_cbs.exit_callbacks);
 #ifndef CONFIG_USER_ONLY
     cpu->as = &address_space_memory;
     cpu->thread_id = qemu_get_thread_id();
diff --git a/include/qom/cpu.h b/include/qom/cpu.h
index 8d121b3..0ec020b 100644
--- a/include/qom/cpu.h
+++ b/include/qom/cpu.h
@@ -201,6 +201,24 @@ typedef struct CPUWatchpoint {
     QTAILQ_ENTRY(CPUWatchpoint) entry;
 } CPUWatchpoint;
 
+/* vCPU exit callbacks */
+typedef void (*CPUExitCallback)(CPUState *cpu, void *opaque);
+struct CPUExitCBs {
+    QemuMutex mutex;
+    QTAILQ_HEAD(exit_callbacks_head, CPUExitCB) exit_callbacks;
+};
+
+typedef struct CPUExitCB {
+    CPUExitCallback callback;
+    void *opaque;
+
+    QTAILQ_ENTRY(CPUExitCB) entry;
+} CPUExitCB;
+
+void cpu_exit_callback_add(CPUState *cpu, CPUExitCallback callback,
+                           void *opaque);
+void cpu_exit_callbacks_call_all(CPUState *cpu);
+
 /* Rendezvous support */
 #define TCG_RDV_POLLING_PERIOD 10
 typedef struct CpuExitRendezvous {
@@ -305,6 +323,8 @@ struct CPUState {
 
     void *opaque;
 
+    /* One-shot callbacks for stopping requests. */
+    struct CPUExitCBs exit_cbs;
     volatile int pending_rdv;
 
     /* In order to avoid passing too many arguments to the MMIO helpers,
-- 
2.4.5