| Message ID | 20230306015710.1868853-3-richard.henderson@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | tcg: Issue memory barriers for guest memory model | expand |
On 6/3/23 02:57, Richard Henderson wrote: > 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(-) Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
diff --git a/tcg/tcg-op.c b/tcg/tcg-op.c index 75fdcdaac7..2721c1cab9 100644 --- a/tcg/tcg-op.c +++ b/tcg/tcg-op.c @@ -107,8 +107,13 @@ void tcg_gen_mb(TCGBar mb_type) * (i.e. !(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(-)