From patchwork Tue Jan 31 09:05:08 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pavel Dovgalyuk X-Patchwork-Id: 9546735 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 6A62C604A0 for ; Tue, 31 Jan 2017 09:05:34 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 5BF6926247 for ; Tue, 31 Jan 2017 09:05:34 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 5081B28285; Tue, 31 Jan 2017 09:05:34 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 5933C26247 for ; Tue, 31 Jan 2017 09:05:32 +0000 (UTC) Received: from localhost ([::1]:36779 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cYUNX-0000py-Gk for patchwork-qemu-devel@patchwork.kernel.org; Tue, 31 Jan 2017 04:05:31 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42769) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cYUNI-0000pe-8p for qemu-devel@nongnu.org; Tue, 31 Jan 2017 04:05:17 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cYUND-0005Vd-A5 for qemu-devel@nongnu.org; Tue, 31 Jan 2017 04:05:16 -0500 Received: from mail.ispras.ru ([83.149.199.45]:39698) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cYUNC-0005UF-VM for qemu-devel@nongnu.org; Tue, 31 Jan 2017 04:05:11 -0500 Received: from PASHAISP (unknown [85.142.117.226]) by mail.ispras.ru (Postfix) with ESMTPSA id 7A5BC5400A1; Tue, 31 Jan 2017 12:05:07 +0300 (MSK) From: "Pavel Dovgalyuk" To: "'Paolo Bonzini'" , References: <20170129210910.6333-1-pbonzini@redhat.com> In-Reply-To: <20170129210910.6333-1-pbonzini@redhat.com> Date: Tue, 31 Jan 2017 12:05:08 +0300 Message-ID: <000601d27ba1$1f009a50$5d01cef0$@ru> MIME-Version: 1.0 X-Mailer: Microsoft Office Outlook 12.0 Thread-Index: AdJ6c/D7/2e2GHOER1WOyrObZP0uFwBJibuQ Content-Language: ru X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 83.149.199.45 Subject: Re: [Qemu-devel] [RFC/RFT PATCH 0/7] cpu-exec: simplify cpu_exec and remove some icount special cases X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: serge.fdrv@gmail.com, pavel.dovgaluk@ispras.ru, peter.maydell@linaro.org Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Hi, Paolo! Thanks for refactoring. I tested these patches with icount record/replay on i386 machine. It works, but the following changes should be applied. I also removed call to replay_has_interrupt, because now it is not needed here. It seems, that this call is an artifact of an older record/replay revision. Pavel Dovgalyuk > -----Original Message----- > From: Paolo Bonzini [mailto:paolo.bonzini@gmail.com] On Behalf Of Paolo Bonzini > Sent: Monday, January 30, 2017 12:09 AM > To: qemu-devel@nongnu.org > Cc: serge.fdrv@gmail.com; peter.maydell@linaro.org; pavel.dovgaluk@ispras.ru > Subject: [RFC/RFT PATCH 0/7] cpu-exec: simplify cpu_exec and remove some icount special cases > > 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. > > 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(-) > > -- > 2.9.3 diff --git a/cpu-exec.c b/cpu-exec.c index 3838eb8..5cef8bc 100644 --- a/cpu-exec.c +++ b/cpu-exec.c @@ -519,7 +519,8 @@ static inline bool cpu_handle_interrupt(CPUState *cpu, } /* Finally, check if we need to exit to the main loop. */ - if (unlikely(atomic_read(&cpu->exit_request) || replay_has_interrupt())) { + if (unlikely(atomic_read(&cpu->exit_request) + || (use_icount && cpu->icount_decr.u16.low + cpu->icount_extra == 0))) { atomic_set(&cpu->exit_request, 0); cpu->exception_index = EXCP_INTERRUPT; return true;