From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56066) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bFG6g-0005Pq-0a for qemu-devel@nongnu.org; Tue, 21 Jun 2016 03:28:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bFG6b-0007kP-WE for qemu-devel@nongnu.org; Tue, 21 Jun 2016 03:28:21 -0400 Received: from mail-lf0-x243.google.com ([2a00:1450:4010:c07::243]:36589) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bFG6b-0007kI-OZ for qemu-devel@nongnu.org; Tue, 21 Jun 2016 03:28:17 -0400 Received: by mail-lf0-x243.google.com with SMTP id a2so1491122lfe.3 for ; Tue, 21 Jun 2016 00:28:17 -0700 (PDT) Sender: Paolo Bonzini References: <20160618040343.19517-1-bobby.prani@gmail.com> <20160618040343.19517-15-bobby.prani@gmail.com> From: Paolo Bonzini Message-ID: <06f042ba-91b2-d751-e53e-6e5ca56081d3@redhat.com> Date: Tue, 21 Jun 2016 09:28:15 +0200 MIME-Version: 1.0 In-Reply-To: <20160618040343.19517-15-bobby.prani@gmail.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC v3 PATCH 14/14] target-i386: Generate fences for x86 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Pranith Kumar , Richard Henderson , Eduardo Habkost , "open list:All patches CC here" Cc: serge.fdrv@gmail.com, alex.bennee@linaro.org On 18/06/2016 06:03, Pranith Kumar wrote: > Signed-off-by: Pranith Kumar > --- > target-i386/translate.c | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/target-i386/translate.c b/target-i386/translate.c > index bf33e6b..32b0f5c 100644 > --- a/target-i386/translate.c > +++ b/target-i386/translate.c > @@ -8012,13 +8012,17 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s, > || (prefixes & PREFIX_LOCK)) { > goto illegal_op; > } > + tcg_gen_mb(TCG_MO_ST_ST | TCG_BAR_SC); > break; > case 0xe8 ... 0xef: /* lfence */ > + tcg_gen_mb(TCG_MO_LD_LD | TCG_BAR_SC); > + break; These are unnecessary. On the other hand, _each and every load_ must be followed by a LD_LD | LD_ST barrier, and each and every store must be preceded by a LD_ST | ST_ST barrier. Paolo > case 0xf0 ... 0xf7: /* mfence */ > if (!(s->cpuid_features & CPUID_SSE2) > || (prefixes & PREFIX_LOCK)) { > goto illegal_op; > } > + tcg_gen_mb(TCG_MO_ALL | TCG_BAR_SC); > break; > > default: >