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 DBC6BC8300A for ; Thu, 30 Apr 2020 12:45:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B52AA205ED for ; Thu, 30 Apr 2020 12:45:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="GfLDdMcT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726793AbgD3Mpe (ORCPT ); Thu, 30 Apr 2020 08:45:34 -0400 Received: from us-smtp-1.mimecast.com ([205.139.110.61]:53420 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726520AbgD3Mpe (ORCPT ); Thu, 30 Apr 2020 08:45:34 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1588250733; 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=/Cb5HHKbQwivw+27kErpeaVpuk6fg8e7FOLW1l12fCc=; b=GfLDdMcTZ0juKuTCnm8BNOYrgkEdq0wYYLxnaBowclMo8qUSvQ/jdtQfFSjvYm3J4IM0hL jh1gaTi1CPpD9T6xMSNvZO5bfGfxFcZpFlMKb9mWvpyita2o1pSBLS0+FMNsKQPLzYJ+XS mF6b4pyeYi8NOVlKsVLD9bQUNH6/Yc0= Received: from mail-wr1-f69.google.com (mail-wr1-f69.google.com [209.85.221.69]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-228-Gjilz1DZNGmErwor0gFowA-1; Thu, 30 Apr 2020 08:45:31 -0400 X-MC-Unique: Gjilz1DZNGmErwor0gFowA-1 Received: by mail-wr1-f69.google.com with SMTP id a12so645363wrv.3 for ; Thu, 30 Apr 2020 05:45:31 -0700 (PDT) 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=/Cb5HHKbQwivw+27kErpeaVpuk6fg8e7FOLW1l12fCc=; b=A78HE2+vBu6AddVPrasN9yrxq6tUPTQxTudTp8Em+a30Cuewkeob9vykYJdUmjCOQT Y1rUOu3IMRpX0+wruIo4e4EAfoPBcHliASd3uEAmy0dJnNh7dtyocb6NakyufE1tkMc0 9KVNd8pTzs/IC4OOXnmtgQynPsLRsg6A6VKSOrgb3V4XOoU5+ieu65mf8MuzBFqgkArM O7iT1USs4lU+HB1haHq+pbRrAxbKfahZU5zBIO8dKDv7hFP8KnIFJVqUMI5euYo6+jyJ GMLCOXqcjjxBrCSLtTuEUjeBZRgDVUfV5fYAf1eMhSVL/s2wNnx6wSsxsb5FAtHVNsiw 4scQ== X-Gm-Message-State: AGi0PuZM4x25TzdLZQpYP61gIXjxJLWFK3GmQ4RWQyxyADTLDQs2o1cr o0I+mvv+SKMwzGpsi2bQPvWRKXd/Viudiyn3UIXNlaYQEdRtKjqnsNQoaefDtMP2nNMpuYJJiFk Z4SBG3G9bf1T2EAXdwY7+7IIs X-Received: by 2002:a1c:6787:: with SMTP id b129mr2890868wmc.165.1588250729955; Thu, 30 Apr 2020 05:45:29 -0700 (PDT) X-Google-Smtp-Source: APiQypJHyik7w72yZvX6PX+sEPiltOuJ0kE1Z2Mjczffq8o7emZek2HBnjq6JmtiOcFDW1lscPKysw== X-Received: by 2002:a1c:6787:: with SMTP id b129mr2890837wmc.165.1588250729563; Thu, 30 Apr 2020 05:45:29 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:ac19:d1fb:3f5f:d54f? ([2001:b07:6468:f312:ac19:d1fb:3f5f:d54f]) by smtp.gmail.com with ESMTPSA id t20sm11667993wmi.2.2020.04.30.05.45.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 Apr 2020 05:45:29 -0700 (PDT) Subject: Re: [PATCH] KVM: x86: handle wrap around 32-bit address space To: David Laight , 'Jim Mattson' Cc: 'LKML' , 'kvm list' , 'Sean Christopherson' , 'Joerg Roedel' , "'everdox@gmail.com'" References: <20200427165917.31799-1-pbonzini@redhat.com> <91c76eb0edcd4f1a9d5bc541d35f8ade@AcuMS.aculab.com> From: Paolo Bonzini Message-ID: <2f471fbc-99fb-1a85-8f9f-c276c897f518@redhat.com> Date: Thu, 30 Apr 2020 14:45:19 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <91c76eb0edcd4f1a9d5bc541d35f8ade@AcuMS.aculab.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 29/04/20 10:56, David Laight wrote: >>>> + if (unlikely(((rip ^ orig_rip) >> 31) == 3) && !is_64_bit_mode(vcpu)) >> Isn't the more obvious: >> if (((rip ^ orig_rip) & 1ull << 32) ... >> equivalent? This one would not (it would also detect carry on high memory addresses, not just 0x7fffffff to 0x80000000)... > Actually not even being clever, how about: > if (orig_rip < (1ull << 32) && unlikely(rip >= (1ull << 32)) && ... ... but yes this one would be equivalent. Paolo