[RFC PATCH 3/9] plugins: Expose Transaction Block cache flush API to plugins

[Ruslan Ruslichenko <ruslichenko.r@gmail.com>]

From: Ruslan Ruslichenko <Ruslan_Ruslichenko@epam.com>

The patch introduces qemu_plugin_flush_tb_cache() to the plugin API,
allowing plugins to invalidate QEMU translate code cache.

If a plugin needs to dynamically register a new instruction or memory
callback, the new hooks may not be triggered for code blocks that
QEMU has already translated and cached. This API allows QEMU
re-translate TB, so that new applied hooks will take effect.

Signed-off-by: Ruslan Ruslichenko <Ruslan_Ruslichenko@epam.com>
---
 include/plugins/qemu-plugin.h |  3 +++
 plugins/api.c                 |  6 ++++++
 plugins/core.c                | 11 +++++++++++
 plugins/plugin.h              |  2 ++
 4 files changed, 22 insertions(+)

diff --git a/include/plugins/qemu-plugin.h b/include/plugins/qemu-plugin.h
index bbd21e79c5..a68427536f 100644
--- a/include/plugins/qemu-plugin.h
+++ b/include/plugins/qemu-plugin.h
@@ -1246,6 +1246,9 @@ void qemu_plugin_u64_set(qemu_plugin_u64 entry, unsigned int vcpu_index,
 QEMU_PLUGIN_API
 uint64_t qemu_plugin_u64_sum(qemu_plugin_u64 entry);
 
+QEMU_PLUGIN_API
+void qemu_plugin_flush_tb_cache(void);
+
 QEMU_PLUGIN_API
 uint64_t qemu_plugin_get_virtual_clock_ns(void);
 
diff --git a/plugins/api.c b/plugins/api.c
index 609ea69293..fa650e1219 100644
--- a/plugins/api.c
+++ b/plugins/api.c
@@ -653,6 +653,12 @@ uint64_t qemu_plugin_u64_sum(qemu_plugin_u64 entry)
     return total;
 }
 
+QEMU_PLUGIN_API
+void qemu_plugin_flush_tb_cache(void)
+{
+    plugin_flush_tb_cache();
+}
+
 typedef struct {
     void (*cb)(void *opaque);
     void* opaque;
diff --git a/plugins/core.c b/plugins/core.c
index 42fd986593..462f4bae81 100644
--- a/plugins/core.c
+++ b/plugins/core.c
@@ -21,6 +21,7 @@
 #include "qemu/rcu.h"
 #include "exec/tb-flush.h"
 #include "tcg/tcg-op-common.h"
+#include "qemu/main-loop.h"
 #include "plugin.h"
 
 struct qemu_plugin_cb {
@@ -888,3 +889,13 @@ enum qemu_plugin_cb_flags tcg_call_to_qemu_plugin_cb_flags(int flags)
         return QEMU_PLUGIN_CB_RW_REGS;
     }
 }
+
+void plugin_flush_tb_cache(void)
+{
+    CPUState *cpu = qemu_get_cpu(0);
+    if (cpu) {
+        queue_tb_flush(cpu);
+
+        qemu_cpu_kick(cpu);
+    }
+}
diff --git a/plugins/plugin.h b/plugins/plugin.h
index 6fbc443b96..0bf819536b 100644
--- a/plugins/plugin.h
+++ b/plugins/plugin.h
@@ -125,4 +125,6 @@ void plugin_scoreboard_free(struct qemu_plugin_scoreboard *score);
  */
 void qemu_plugin_fillin_mode_info(qemu_info_t *info);
 
+void plugin_flush_tb_cache(void);
+
 #endif /* PLUGIN_H */
-- 
2.43.0