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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no 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 CA3BDC433E0 for ; Tue, 12 Jan 2021 07:53:59 +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 55FC122DFA for ; Tue, 12 Jan 2021 07:53:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 55FC122DFA Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=yadro.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:45466 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kzEV4-0005dI-BC for qemu-devel@archiver.kernel.org; Tue, 12 Jan 2021 02:53:58 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:40516) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kzEQV-0001H0-Qy for qemu-devel@nongnu.org; Tue, 12 Jan 2021 02:49:15 -0500 Received: from mta-02.yadro.com ([89.207.88.252]:57452 helo=mta-01.yadro.com) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kzEQQ-0002ZW-Jr for qemu-devel@nongnu.org; Tue, 12 Jan 2021 02:49:15 -0500 Received: from localhost (unknown [127.0.0.1]) by mta-01.yadro.com (Postfix) with ESMTP id 5008441281; Tue, 12 Jan 2021 07:49:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=yadro.com; h= in-reply-to:content-disposition:content-type:content-type :mime-version:references:message-id:subject:subject:from:from :date:date:received:received:received; s=mta-01; t=1610437748; x=1612252149; bh=c32G32UNidd+PrbbuZoCj/w4KoLbbHTQ8HClasD67Gc=; b= aVX6hnTZL1aB+RLxIFkJnnvOjONBScCRYFEQBAAgMME8qZVNpt49Vqh3tyOSenTk 3HVZsbwN0VTghGaTj/85W693vydwmXc7ZZNe8RnnZh2VjQaWYMstjB7s97jz3vzq saMWBDZNrkoUXHCpcXqkmkHr5lwQQMdTJrnOw9MtUDw= X-Virus-Scanned: amavisd-new at yadro.com Received: from mta-01.yadro.com ([127.0.0.1]) by localhost (mta-01.yadro.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 2L2Umezj_fH6; Tue, 12 Jan 2021 10:49:08 +0300 (MSK) Received: from T-EXCH-03.corp.yadro.com (t-exch-03.corp.yadro.com [172.17.100.103]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by mta-01.yadro.com (Postfix) with ESMTPS id 053C1412FC; Tue, 12 Jan 2021 10:49:08 +0300 (MSK) Received: from localhost (172.17.204.212) by T-EXCH-03.corp.yadro.com (172.17.100.103) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384_P384) id 15.1.669.32; Tue, 12 Jan 2021 10:49:07 +0300 Date: Tue, 12 Jan 2021 10:49:07 +0300 From: Roman Bolshakov To: Richard Henderson Subject: Re: [PATCH] hvf: guard xgetbv call. Message-ID: References: <8da22f7f-7379-cffe-5fdd-94fd5ddece32@linaro.org> <4a24ae1a-8114-a840-b6bf-ae3a301f6232@linaro.org> <259b9e96-1f69-4e4a-16ef-7034e19ed1ef@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <259b9e96-1f69-4e4a-16ef-7034e19ed1ef@linaro.org> X-Originating-IP: [172.17.204.212] X-ClientProxiedBy: T-EXCH-01.corp.yadro.com (172.17.10.101) To T-EXCH-03.corp.yadro.com (172.17.100.103) Received-SPF: pass client-ip=89.207.88.252; envelope-from=r.bolshakov@yadro.com; helo=mta-01.yadro.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, 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: Peter Maydell , QEMU Developers , Cameron Esfahani , John Arbuckle , Hill Ma , Paolo Bonzini , Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, Jan 11, 2021 at 07:06:22AM -1000, Richard Henderson wrote: > On 1/10/21 6:31 PM, Roman Bolshakov wrote: > >> Also, if we're going to put this some place common, forcing the caller to do > >> the cpuid that feeds this, then we should probably make all of the startup > >> cpuid stuff common as well. > >> > > > > I proposed the version because all callers of xgetbv instruction already > > call cpuid before invoking inline xgetbv. > > > >> Note that we'd probably have to use constructor priorities to get that right > >> for util/bufferiszero.c. > >> > > > > Please correct me if I read this wrong. What you're saying is we should > > initialize cpuid in constructors and then use cached cpuid ecx in > > xgetbv() (and drop one argument, respectively)? > > I would have xgetbv and all of the cpuid values cached at startup, and all > three places would read global variables. > It makes sense, thanks for the clarification. Do you think it should be part of the change Hill is doing or it might be a follow-up cleanup patch? -Roman