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=-7.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,NICE_REPLY_A,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 E9D65C433B4 for ; Thu, 8 Apr 2021 16:14:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B9AAD6113A for ; Thu, 8 Apr 2021 16:14:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232059AbhDHQOp (ORCPT ); Thu, 8 Apr 2021 12:14:45 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:32667 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231480AbhDHQOo (ORCPT ); Thu, 8 Apr 2021 12:14:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1617898472; 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=elXf7VW8mYYZHy/sU8ktzpg8oQGZMdhCA5JdOrUTKYM=; b=ePTPm4NNNU74eXhhNNKetskDbjbKbiB2kgTTII/Ehhs5fDye1kC0qcsWC5ebLGNxZW+KOR /peHU9FKntJY3jc/BsFJWwCer/5FLLUPF0wdGMXGR0Fy9xS4RJ8pkj6MuZHdg69s4gZYeZ yPFW8dsoIzZlgJJcIAQ/YQV0j4OiNrk= Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-278-KbwdJxg1PPehvX6xTraz5Q-1; Thu, 08 Apr 2021 12:14:30 -0400 X-MC-Unique: KbwdJxg1PPehvX6xTraz5Q-1 Received: by mail-ed1-f72.google.com with SMTP id a8so1280338edt.1 for ; Thu, 08 Apr 2021 09:14:30 -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=elXf7VW8mYYZHy/sU8ktzpg8oQGZMdhCA5JdOrUTKYM=; b=nlqLmMWNpkOxdEssl9Igk0s5g5dKh56ngBq1hXlRDplvj+wVxhk+ciBMLkymbNqzSP TbUHl2ZTQFj5xDblW3IlqfqWIpdaaiBdBL5NU0dgZsEXQVnYOpuqk+pt1fx+r0iUGaXc znPBvnV50wajh9UyzfjtWzimMHoMUiFTpzUDyzMe2RL+c1a0XX1q8sDqBr7K2tU6mNpS s0bk2LVHQ/AIETg0KSrZVVzXl2S55uc8/wpymqHtirsmIz1xZICBkD559numPFNFscFP JNZ/2MWD8RP243vKv1umUD8lJ7H6jQpsU5QC4fUpla54gORqPYE6tizChjAB8zZwLeK6 4kyw== X-Gm-Message-State: AOAM530Or9jv8X9HqbWPYErqJtsULJXgpE+Sutqho/LELpDvb+mtLplL qdKoR9/LieXL2OL5GK8qSSB+SL0zoT0Ec8/rtJ7D2R0KdBeN4mJfgm2Vz52vDGJc4dpeLeAtWUH DvbbdG3ero06H8Yb9uoO/JO73 X-Received: by 2002:a17:906:1453:: with SMTP id q19mr11664868ejc.76.1617898469489; Thu, 08 Apr 2021 09:14:29 -0700 (PDT) X-Google-Smtp-Source: ABdhPJy2caDACYbDyFw8mNJVcybeWHcKDxGKJYs94P6XujvmFPa5vkdq9RAsvPNL5dt8BX/ewU7oYw== X-Received: by 2002:a17:906:1453:: with SMTP id q19mr11664838ejc.76.1617898469318; Thu, 08 Apr 2021 09:14:29 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:5e2c:eb9a:a8b6:fd3e? ([2001:b07:6468:f312:5e2c:eb9a:a8b6:fd3e]) by smtp.gmail.com with ESMTPSA id bq18sm10535789ejb.27.2021.04.08.09.14.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 08 Apr 2021 09:14:28 -0700 (PDT) Subject: Re: [PATCH] KVM: SVM: Make sure GHCB is mapped before updating To: Tom Lendacky , Sean Christopherson Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, Jim Mattson , Joerg Roedel , Vitaly Kuznetsov , Wanpeng Li , Borislav Petkov , Ingo Molnar , Thomas Gleixner , Brijesh Singh References: <03b349cb19b360d4c2bbeebdd171f99298082d28.1617820214.git.thomas.lendacky@amd.com> From: Paolo Bonzini Message-ID: <2b282772-afaa-2fd4-0794-4449eda6fd02@redhat.com> Date: Thu, 8 Apr 2021 18:14:27 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/04/21 18:04, Tom Lendacky wrote: >>>> + if (!err || !sev_es_guest(vcpu->kvm) || !WARN_ON_ONCE(svm->ghcb)) >>> This should be WARN_ON_ONCE(!svm->ghcb), otherwise you'll get the right >>> result, but get a stack trace immediately. >> Doh, yep. > Actually, because of the "or's", this needs to be: > > if (!err || !sev_es_guest(vcpu->kvm) || (sev_es_guest(vcpu->kvm) && WARN_ON_ONCE(!svm->ghcb))) No, || cuts the right-hand side if the left-hand side is true. So: - if err == 0, the rest is not evaluated - if !sev_es_guest(vcpu->kvm), WARN_ON_ONCE(!svm->ghcb) is not evaluated Paolo