[PATCH v11 11/14] tb-stats: reset the tracked TBs on a tb_flush

[Fei Wu]

From: Alex Bennée <alex.bennee@linaro.org>

We keep track of translations but can only do so up until the
translation cache is flushed. At that point we really have no idea if
we can re-create a translation because all the active tracking
information has been reset.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
 accel/tcg/tb-maint.c    |  1 +
 accel/tcg/tb-stats.c    | 19 +++++++++++++++++++
 include/exec/tb-stats.h |  8 ++++++++
 3 files changed, 28 insertions(+)

diff --git a/accel/tcg/tb-maint.c b/accel/tcg/tb-maint.c
index ba1635aa4b..5f946e0285 100644
--- a/accel/tcg/tb-maint.c
+++ b/accel/tcg/tb-maint.c
@@ -762,6 +762,7 @@ static void do_tb_flush(CPUState *cpu, run_on_cpu_data 
tb_flush_count)
     qht_reset_size(&tb_ctx.htable, CODE_GEN_HTABLE_SIZE);
     tb_remove_all();
 
+    tbstats_reset_tbs();
     tcg_region_reset_all();
     /* XXX: flush processor icache at this point if cache flush is expensive */
     qatomic_mb_set(&tb_ctx.tb_flush_count, tb_ctx.tb_flush_count + 1);
diff --git a/accel/tcg/tb-stats.c b/accel/tcg/tb-stats.c
index 61bfbe96fc..56e944b225 100644
--- a/accel/tcg/tb-stats.c
+++ b/accel/tcg/tb-stats.c
@@ -269,6 +269,25 @@ void do_hmp_tbstats_safe(CPUState *cpu, run_on_cpu_data 
icmd)
     g_free(cmdinfo);
 }
 
+/*
+ * We have to reset the tbs array on a tb_flush as those
+ * TranslationBlocks no longer exist and we no loner know if the
+ * current mapping is still valid.
+ */
+
+static void reset_tbs_array(void *p, uint32_t hash, void *userp)
+{
+    TBStatistics *tbs = p;
+    g_ptr_array_set_size(tbs->tbs, 0);
+}
+
+void tbstats_reset_tbs(void)
+{
+    if (tb_ctx.tb_stats.map) {
+        qht_iter(&tb_ctx.tb_stats, reset_tbs_array, NULL);
+    }
+}
+
 void init_tb_stats_htable(void)
 {
     if (!tb_ctx.tb_stats.map && tb_stats_collection_enabled()) {
diff --git a/include/exec/tb-stats.h b/include/exec/tb-stats.h
index 33eed8d385..ec47cbecc2 100644
--- a/include/exec/tb-stats.h
+++ b/include/exec/tb-stats.h
@@ -125,4 +125,12 @@ struct TbstatsCommand {
 
 void do_hmp_tbstats_safe(CPUState *cpu, run_on_cpu_data icmd);
 
+/**
+ * tbstats_reset_tbs: reset the linked array of TBs
+ *
+ * Reset the list of tbs for a given array. Should be called from
+ * safe work during tb_flush.
+ */
+void tbstats_reset_tbs(void);
+
 #endif
-- 
2.25.1