From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:34260) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cdyuf-0000Ho-4s for qemu-devel@nongnu.org; Wed, 15 Feb 2017 07:42:26 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cdyuc-00033a-1Q for qemu-devel@nongnu.org; Wed, 15 Feb 2017 07:42:25 -0500 Received: from mail-wm0-x242.google.com ([2a00:1450:400c:c09::242]:32816) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1cdyub-000339-Qa for qemu-devel@nongnu.org; Wed, 15 Feb 2017 07:42:21 -0500 Received: by mail-wm0-x242.google.com with SMTP id v77so8003317wmv.0 for ; Wed, 15 Feb 2017 04:42:20 -0800 (PST) Sender: Paolo Bonzini References: <20170129210910.6333-1-pbonzini@redhat.com> From: Paolo Bonzini Message-ID: <0775ca1e-ecdb-39a1-d2e9-6e410f0d4e54@redhat.com> Date: Wed, 15 Feb 2017 13:42:21 +0100 MIME-Version: 1.0 In-Reply-To: <20170129210910.6333-1-pbonzini@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [RFC/RFT PATCH 0/7] cpu-exec: simplify cpu_exec and remove some icount special cases List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: serge.fdrv@gmail.com, pavel.dovgaluk@ispras.ru, peter.maydell@linaro.org On 29/01/2017 22:09, Paolo Bonzini wrote: > The series includes three parts: > > 1-2: fix two bugs, the first one pretty bad, the second seems > to be theoretical only. > > 3-5: simplify cpu_exec. This builds on Sergey's conversion > of cpu_exec to a simple top-down logic, making the phases > clearer and saving on the cost of siglongjmp in the meanwhile. I'll include these five in my next pull request. Review for patch 6 is welcome! Paolo > 6-7: these are intended to be a base for Pavel's record/replay > fixes. The main thing I noticed while reviewing is that icount > is redoing (with u16.high) a lot of things that tcg_exit_req is > doing too. This is because, at the time icount was introduced, > tcg_exit_req didn't exist and QEMU instead unwound chained TBs > through POSIX signals. But now we have essentially two ways to > do the same thing with subtly different invariants or downright > bugs (such as the one fixed by patch 1). Patch 6 therefore > unifies tcg_exit_req and the icount interrupt flag. It saves a > handful of instructions per TB in icount mode and generally > makes icount mode "less special", which is a good thing since > no one seems to understand it well. Patch 7 then removes another > EXCP_INTERRUPT/cpu_loop_exit pair; by exiting to main loop simply > through cpu->exit_request, hopefully it fixes one of the issues that > Pavel was seeing. > > For now I've tested this only on an aarch64 Linux image (with > and without -icount). Thanks, > > Paolo > > Paolo Bonzini (7): > cpu-exec: fix jmp_first out-of-bounds access with icount > cpu-exec: tighten barrier on TCG_EXIT_REQUESTED > cpu-exec: avoid cpu_loop_exit in cpu_handle_interrupt > cpu-exec: avoid repeated sigsetjmp on interrupts > cpu-exec: remove outermost infinite loop > cpu-exec: unify icount_decr and tcg_exit_req > cpu-exec: centralize exiting to the main loop > > cpu-exec.c | 153 +++++++++++++++++++++------------------------- > include/exec/exec-all.h | 1 + > include/exec/gen-icount.h | 53 ++++++++-------- > include/qom/cpu.h | 15 +++-- > qom/cpu.c | 2 +- > tcg/tcg.h | 1 - > translate-all.c | 2 +- > translate-common.c | 13 ++-- > 8 files changed, 109 insertions(+), 131 deletions(-) >