We don't need to allocate plugin context at startup,
we can wait until we actually use it.

Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 accel/tcg/plugin-gen.c | 36 ++++++++++++++++++++----------------
 tcg/tcg.c              | 11 -----------
 2 files changed, 20 insertions(+), 27 deletions(-)

diff --git a/accel/tcg/plugin-gen.c b/accel/tcg/plugin-gen.c
index b54494712a..54b08ffc9e 100644
--- a/accel/tcg/plugin-gen.c
+++ b/accel/tcg/plugin-gen.c
@@ -305,28 +305,32 @@ static void plugin_gen_inject(struct qemu_plugin_tb *plugin_tb)
 
 bool plugin_gen_tb_start(CPUState *cpu, const DisasContextBase *db)
 {
-    bool ret = false;
+    struct qemu_plugin_tb *ptb;
 
-    if (test_bit(QEMU_PLUGIN_EV_VCPU_TB_TRANS, cpu->plugin_state->event_mask)) {
-        struct qemu_plugin_tb *ptb = tcg_ctx->plugin_tb;
-
-        /* reset callbacks */
-        if (ptb->cbs) {
-            g_array_set_size(ptb->cbs, 0);
-        }
-        ptb->n = 0;
-
-        ret = true;
-
-        ptb->mem_helper = false;
-
-        tcg_gen_plugin_cb(PLUGIN_GEN_FROM_TB);
+    if (!test_bit(QEMU_PLUGIN_EV_VCPU_TB_TRANS,
+                  cpu->plugin_state->event_mask)) {
+        return false;
     }
 
     tcg_ctx->plugin_db = db;
     tcg_ctx->plugin_insn = NULL;
+    ptb = tcg_ctx->plugin_tb;
 
-    return ret;
+    if (ptb) {
+        /* Reset callbacks */
+        if (ptb->cbs) {
+            g_array_set_size(ptb->cbs, 0);
+        }
+        ptb->n = 0;
+        ptb->mem_helper = false;
+    } else {
+        ptb = g_new0(struct qemu_plugin_tb, 1);
+        tcg_ctx->plugin_tb = ptb;
+        ptb->insns = g_ptr_array_new();
+    }
+
+    tcg_gen_plugin_cb(PLUGIN_GEN_FROM_TB);
+    return true;
 }
 
 void plugin_gen_insn_start(CPUState *cpu, const DisasContextBase *db)
diff --git a/tcg/tcg.c b/tcg/tcg.c
index 71daa5d268..34e3056380 100644
--- a/tcg/tcg.c
+++ b/tcg/tcg.c
@@ -761,14 +761,6 @@ QEMU_BUILD_BUG_ON((int)(offsetof(CPUNegativeOffsetState, tlb.f[0]) -
                   < MIN_TLB_MASK_TABLE_OFS);
 #endif
 
-static void alloc_tcg_plugin_context(TCGContext *s)
-{
-#ifdef CONFIG_PLUGIN
-    s->plugin_tb = g_new0(struct qemu_plugin_tb, 1);
-    s->plugin_tb->insns = g_ptr_array_new();
-#endif
-}
-
 /*
  * All TCG threads except the parent (i.e. the one that called tcg_context_init
  * and registered the target's TCG globals) must register with this function
@@ -813,7 +805,6 @@ void tcg_register_thread(void)
     qatomic_set(&tcg_ctxs[n], s);
 
     if (n > 0) {
-        alloc_tcg_plugin_context(s);
         tcg_region_initial_alloc(s);
     }
 
@@ -1360,8 +1351,6 @@ static void tcg_context_init(unsigned max_cpus)
         indirect_reg_alloc_order[i] = tcg_target_reg_alloc_order[i];
     }
 
-    alloc_tcg_plugin_context(s);
-
     tcg_ctx = s;
     /*
      * In user-mode we simply share the init context among threads, since we
-- 
2.34.1