| Message ID | 20210316220735.2048137-4-richard.henderson@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | tcg: Issue memory barriers for guest memory model | expand |
diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c index 76dc7d8dc5..c8501508c2 100644 --- a/tcg/tcg-op.c +++ b/tcg/tcg-op.c @@ -102,8 +102,13 @@ void tcg_gen_mb(TCGBar mb_type) * (i.e. !(tb_cflags & CF_PARALLEL)), however, even with a single cpu * we have i/o threads running in parallel, and lack of memory order * can result in e.g. virtio queue entries being read incorrectly. + * + * That said, we can elide anything which the host provides for free. */ - tcg_gen_op1(INDEX_op_mb, mb_type); + mb_type &= ~TCG_TARGET_DEFAULT_MO; + if (mb_type & TCG_MO_ALL) { + tcg_gen_op1(INDEX_op_mb, mb_type); + } } /* 32 bit ops */
Reduce the set of required barriers to those needed by the host right from the beginning. Signed-off-by: Richard Henderson <richard.henderson@linaro.org> --- tcg/tcg-op.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-)