From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5B415C433E6 for ; Tue, 1 Sep 2020 09:45:30 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 2BEEC20665 for ; Tue, 1 Sep 2020 09:45:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2BEEC20665 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:36856 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kD2r3-0003dA-CP for qemu-devel@archiver.kernel.org; Tue, 01 Sep 2020 05:45:29 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41394) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kD2qE-0002hW-VM for qemu-devel@nongnu.org; Tue, 01 Sep 2020 05:44:38 -0400 Received: from mx2.suse.de ([195.135.220.15]:48172) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kD2qC-0002GL-VV for qemu-devel@nongnu.org; Tue, 01 Sep 2020 05:44:38 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 7A095AC97; Tue, 1 Sep 2020 09:44:35 +0000 (UTC) Subject: Re: [PATCH v6 11/16] cpus: remove checks for non-NULL cpus_accel To: Roman Bolshakov References: <20200901072201.7133-1-cfontana@suse.de> <20200901072201.7133-12-cfontana@suse.de> <20200901093418.GC22344@SPB-NB-133.local> From: Claudio Fontana Message-ID: Date: Tue, 1 Sep 2020 11:44:33 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.11.0 MIME-Version: 1.0 In-Reply-To: <20200901093418.GC22344@SPB-NB-133.local> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=195.135.220.15; envelope-from=cfontana@suse.de; helo=mx2.suse.de X-detected-operating-system: by eggs.gnu.org: First seen = 2020/09/01 00:13:10 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x (no timestamps) [generic] X-Spam_score_int: -62 X-Spam_score: -6.3 X-Spam_bar: ------ X-Spam_report: (-6.3 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-2.13, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Laurent Vivier , Peter Maydell , Thomas Huth , Alberto Garcia , Eduardo Habkost , Pavel Dovgalyuk , =?UTF-8?Q?Alex_Benn=c3=a9e?= , haxm-team@intel.com, Marcelo Tosatti , qemu-devel@nongnu.org, Markus Armbruster , Colin Xu , Wenchao Wang , Paolo Bonzini , Sunil Muthuswamy , =?UTF-8?Q?Philippe_Mathieu-Daud=c3=a9?= , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 9/1/20 11:34 AM, Roman Bolshakov wrote: > On Tue, Sep 01, 2020 at 09:21:56AM +0200, Claudio Fontana wrote: >> now that all accelerators support the CpusAccel interface, >> we can remove most checks for non-NULL cpus_accel, >> we just add a sanity check/assert at vcpu creation. >> >> Signed-off-by: Claudio Fontana >> --- >> softmmu/cpus.c | 33 +++++++++++++++++++++------------ >> 1 file changed, 21 insertions(+), 12 deletions(-) >> >> diff --git a/softmmu/cpus.c b/softmmu/cpus.c >> index 3d8350fba9..f32ecb4bb9 100644 >> --- a/softmmu/cpus.c >> +++ b/softmmu/cpus.c >> @@ -166,34 +166,46 @@ void cpu_synchronize_all_pre_loadvm(void) >> >> void cpu_synchronize_state(CPUState *cpu) >> { >> - if (cpus_accel && cpus_accel->synchronize_state) { >> + if (cpus_accel->synchronize_state) { >> cpus_accel->synchronize_state(cpu); >> } >> } >> >> void cpu_synchronize_post_reset(CPUState *cpu) >> { >> - if (cpus_accel && cpus_accel->synchronize_post_reset) { >> + if (cpus_accel->synchronize_post_reset) { >> cpus_accel->synchronize_post_reset(cpu); >> } >> } >> >> void cpu_synchronize_post_init(CPUState *cpu) >> { >> - if (cpus_accel && cpus_accel->synchronize_post_init) { >> + if (cpus_accel->synchronize_post_init) { >> cpus_accel->synchronize_post_init(cpu); >> } >> } >> >> void cpu_synchronize_pre_loadvm(CPUState *cpu) >> { >> - if (cpus_accel && cpus_accel->synchronize_pre_loadvm) { >> + if (cpus_accel->synchronize_pre_loadvm) { >> cpus_accel->synchronize_pre_loadvm(cpu); >> } >> } >> >> int64_t cpus_get_virtual_clock(void) >> { >> + /* >> + * XXX >> + * >> + * need to check that cpus_accel is not NULL, because qcow2 calls >> + * qemu_get_clock_ns(CLOCK_VIRTUAL) without any accel initialized and >> + * with ticks disabled in some io-tests: >> + * 030 040 041 060 099 120 127 140 156 161 172 181 191 192 195 203 229 249 256 267 >> + * >> + * is this expected? >> + * >> + * XXX >> + */ >> if (cpus_accel && cpus_accel->get_virtual_clock) { >> return cpus_accel->get_virtual_clock(); >> } >> @@ -207,7 +219,7 @@ int64_t cpus_get_virtual_clock(void) >> */ >> int64_t cpus_get_elapsed_ticks(void) >> { >> - if (cpus_accel && cpus_accel->get_elapsed_ticks) { >> + if (cpus_accel->get_elapsed_ticks) { >> return cpus_accel->get_elapsed_ticks(); >> } >> return cpu_get_ticks(); >> @@ -399,7 +411,7 @@ void cpus_kick_thread(CPUState *cpu) >> void qemu_cpu_kick(CPUState *cpu) >> { >> qemu_cond_broadcast(cpu->halt_cond); >> - if (cpus_accel && cpus_accel->kick_vcpu_thread) { >> + if (cpus_accel->kick_vcpu_thread) { >> cpus_accel->kick_vcpu_thread(cpu); >> } else { /* default */ >> cpus_kick_thread(cpu); >> @@ -573,12 +585,9 @@ void qemu_init_vcpu(CPUState *cpu) >> cpu_address_space_init(cpu, 0, "cpu-memory", cpu->memory); >> } >> >> - if (cpus_accel) { >> - /* accelerator already implements the CpusAccel interface */ >> - cpus_accel->create_vcpu_thread(cpu); >> - } else { >> - g_assert_not_reached(); >> - } >> + /* accelerators all implement the CpusAccel interface */ >> + g_assert(cpus_accel != NULL && cpus_accel->create_vcpu_thread != NULL); >> + cpus_accel->create_vcpu_thread(cpu); >> >> while (!cpu->created) { >> qemu_cond_wait(&qemu_cpu_cond, &qemu_global_mutex); >> -- >> 2.26.2 >> > > Reviewed-by: Roman Bolshakov > > but I still find the condition (if cpus_accel->func) redundant, is it > feasible to drop it? > > Regards, > Roman > Hi Roman, indeed currently not, because currently we use a NULL function pointer to mean "use generic/default behaviour". This is one of the open questions in the cover letter. It has the advantage that only "interesting" information is present in each data structure, with only non-default behaviour being explicit, this has been changed to satisfy Paolo's requirement. It has the disadvantage of an additional check. I am ok with both outcomes, but I'd like Paolo's take on this if we are to change this again? Thanks, Claudio