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=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 2F292C3F2D1 for ; Tue, 3 Mar 2020 17:44:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0856B20870 for ; Tue, 3 Mar 2020 17:44:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BerRdVgu" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729612AbgCCRoT (ORCPT ); Tue, 3 Mar 2020 12:44:19 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:49042 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728022AbgCCRoT (ORCPT ); Tue, 3 Mar 2020 12:44:19 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1583257458; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=+kDNjT2v7RCGN2/RZBTOd7SE7Zwpp1JBRccPdNRTagU=; b=BerRdVguQkn/wVKsGfiu9xhV0/5S169JlwxlIW1vpqWB/3Pokvs0aN8YMnj74IHwdotpvC jcilsBKotwU9dnY46bNOymrNQngmKDoB/I00LfPUDnX4t+COmp0naeZBkSagvDf957brSH YuFmBp8y/zTbbED4mPgv0nk7iZMXi+8= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-263-Xg25iwFUPWe3rjs8EoMAnQ-1; Tue, 03 Mar 2020 12:44:16 -0500 X-MC-Unique: Xg25iwFUPWe3rjs8EoMAnQ-1 Received: by mail-wr1-f72.google.com with SMTP id z16so1547573wrm.15 for ; Tue, 03 Mar 2020 09:44:16 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=+kDNjT2v7RCGN2/RZBTOd7SE7Zwpp1JBRccPdNRTagU=; b=U8N3MLk+h/mq9erN4TBhBe6CbulqVjuhwdhbdX0lanKbObiteRPqwW9tTYeW0a7AnW NdX/qrNd1vQCAgEdVCOliE3wCNoS2O4jH/wODAsBkxE2wjOJljOkaim4fIgsEwuemC6D jJlhIkxeUn/Q78p68mkAAXH0gEmnp9mYw03jjt8q0ofejoA7h4/dGb805Pi05SMn0doC jQ4p1YFDkadwflbE+/wKrmtx2wumKmiLYFZN01mm7Z/olc7DuLLKiNJDjWjyZHjg+eHj 5AkbT59aBzJ4j/tpZSvN7jpC4OOWfTY9F97y0ZPUiTBptq6H0eXiAYtC3cJ6eu8/poA4 qfaw== X-Gm-Message-State: ANhLgQ3PnWFUHzx6s3YzSzT8xZb4n3/t0RfqbULxf39XRLjTSQrVn3+j SGJ8Y99/W6uA8HDip64u4MScjCXh26Lpg1/UZ+KnZo/hGWhxErw31vdpEd547Y6rSFFK0zWaUTV L096by6s/wIDc X-Received: by 2002:a1c:1bd6:: with SMTP id b205mr5290790wmb.186.1583257455561; Tue, 03 Mar 2020 09:44:15 -0800 (PST) X-Google-Smtp-Source: ADFU+vs8FxJrSSORXThGbCXQ++IvZ7jOiUFQ+O7eaLn60+Ha62LSmPleWl6D5qSQA/eOUulgtPkXRQ== X-Received: by 2002:a1c:1bd6:: with SMTP id b205mr5290768wmb.186.1583257455198; Tue, 03 Mar 2020 09:44:15 -0800 (PST) Received: from [192.168.178.40] ([151.20.254.94]) by smtp.gmail.com with ESMTPSA id b16sm30986279wrq.14.2020.03.03.09.44.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 03 Mar 2020 09:44:14 -0800 (PST) Subject: Re: [PATCH v2 06/13] KVM: x86: Refactor emulate tracepoint to explicitly take context To: Sean Christopherson Cc: Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20200218232953.5724-1-sean.j.christopherson@intel.com> <20200218232953.5724-7-sean.j.christopherson@intel.com> <8736axjmte.fsf@vitty.brq.redhat.com> <20200303164813.GL1439@linux.intel.com> <2f3f7aff-2bd0-fa62-4b66-9f90f125e44e@redhat.com> <20200303174242.GN1439@linux.intel.com> From: Paolo Bonzini Message-ID: Date: Tue, 3 Mar 2020 18:44:13 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 In-Reply-To: <20200303174242.GN1439@linux.intel.com> Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 03/03/20 18:42, Sean Christopherson wrote: >> As long as we have one use of vcpu, I'd rather skip this patch and >> adjust patch 8 to use "->". Even the other "explicitly take context" >> parts are kinda debatable since you still have to do emul_to_vcpu. >> Throwing a handful of >> >> - struct x86_emulate_ctxt *ctxt = &vcpu->arch.emulate_ctxt; >> + struct x86_emulate_ctxt *ctxt = vcpu->arch.emulate_ctxt; >> >> into patch 8 is not bad at all and limits the churn. > Hmm, I'd prefer to explicitly pass @ctxt, even for the tracepoint. I get > that it's technically unnecessary churn, but explicitly passing @ctxt means > that every funcition that grabs arch.emulate_ctxt (all three of 'em) checks > for a NULL ctxt. That makes it trivial to visually audit that there's no > risk of a bad pointer dereference, and IMO having @ctxt in the prototype > is helpful to see "oh, this helper is called from within the emulator". > That's a good rationale, but I believe this refactoring belongs more in the "disable emulator" part than this one. Paolo