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[PATCH v3 5/5] accel/tcg: Remove check_tcg_memory_orders_compatible
From: |
Richard Henderson |
Subject: |
[PATCH v3 5/5] accel/tcg: Remove check_tcg_memory_orders_compatible |
Date: |
Mon, 19 Jun 2023 16:23:33 +0200 |
We now issue host memory barriers to match the guest memory order.
Continue to disable MTTCG only if the guest has not been ported.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
accel/tcg/tcg-all.c | 39 ++++++++++-----------------------------
1 file changed, 10 insertions(+), 29 deletions(-)
diff --git a/accel/tcg/tcg-all.c b/accel/tcg/tcg-all.c
index 02af6a2891..03dfd67e9e 100644
--- a/accel/tcg/tcg-all.c
+++ b/accel/tcg/tcg-all.c
@@ -64,37 +64,23 @@ DECLARE_INSTANCE_CHECKER(TCGState, TCG_STATE,
* they can set the appropriate CONFIG flags in ${target}-softmmu.mak
*
* Once a guest architecture has been converted to the new primitives
- * there are two remaining limitations to check.
- *
- * - The guest can't be oversized (e.g. 64 bit guest on 32 bit host)
- * - The host must have a stronger memory order than the guest
- *
- * It may be possible in future to support strong guests on weak hosts
- * but that will require tagging all load/stores in a guest with their
- * implicit memory order requirements which would likely slow things
- * down a lot.
+ * there is one remaining limitation to check:
+ * - The guest can't be oversized (e.g. 64 bit guest on 32 bit host)
*/
-static bool check_tcg_memory_orders_compatible(void)
-{
-#if defined(TCG_GUEST_DEFAULT_MO) && defined(TCG_TARGET_DEFAULT_MO)
- return (TCG_GUEST_DEFAULT_MO & ~TCG_TARGET_DEFAULT_MO) == 0;
-#else
- return false;
-#endif
-}
-
static bool default_mttcg_enabled(void)
{
if (icount_enabled() || TCG_OVERSIZED_GUEST) {
return false;
- } else {
-#ifdef TARGET_SUPPORTS_MTTCG
- return check_tcg_memory_orders_compatible();
-#else
- return false;
-#endif
}
+#ifdef TARGET_SUPPORTS_MTTCG
+# ifndef TCG_GUEST_DEFAULT_MO
+# error "TARGET_SUPPORTS_MTTCG without TCG_GUEST_DEFAULT_MO"
+# endif
+ return true;
+#else
+ return false;
+#endif
}
static void tcg_accel_instance_init(Object *obj)
@@ -162,11 +148,6 @@ static void tcg_set_thread(Object *obj, const char *value,
Error **errp)
warn_report("Guest not yet converted to MTTCG - "
"you may get unexpected results");
#endif
- if (!check_tcg_memory_orders_compatible()) {
- warn_report("Guest expects a stronger memory ordering "
- "than the host provides");
- error_printf("This may cause strange/hard to debug errors\n");
- }
s->mttcg_enabled = true;
}
} else if (strcmp(value, "single") == 0) {
--
2.34.1
- [PATCH v3 0/5] tcg: Issue memory barriers for guest memory model, Richard Henderson, 2023/06/19
- [PATCH v3 1/5] target/microblaze: Define TCG_GUEST_DEFAULT_MO, Richard Henderson, 2023/06/19
- [PATCH v3 2/5] tcg: Do not elide memory barriers for !CF_PARALLEL in system mode, Richard Henderson, 2023/06/19
- [PATCH v3 4/5] tcg: Add host memory barriers to cpu_ldst.h interfaces, Richard Henderson, 2023/06/19
- [PATCH v3 5/5] accel/tcg: Remove check_tcg_memory_orders_compatible,
Richard Henderson <=
- [PATCH v3 3/5] tcg: Elide memory barriers implied by the host memory model, Richard Henderson, 2023/06/19
- Re: [PATCH v3 0/5] tcg: Issue memory barriers for guest memory model, Richard Henderson, 2023/06/19
- Re: [PATCH v3 0/5] tcg: Issue memory barriers for guest memory model, Richard Henderson, 2023/06/26