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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A05ECC4332F for ; Tue, 28 Dec 2021 23:38:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237815AbhL1Xi5 (ORCPT ); Tue, 28 Dec 2021 18:38:57 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231460AbhL1Xi5 (ORCPT ); Tue, 28 Dec 2021 18:38:57 -0500 Received: from mail-pl1-x633.google.com (mail-pl1-x633.google.com [IPv6:2607:f8b0:4864:20::633]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61BA9C061574 for ; Tue, 28 Dec 2021 15:38:57 -0800 (PST) Received: by mail-pl1-x633.google.com with SMTP id l16so2518450plg.10 for ; Tue, 28 Dec 2021 15:38:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=mLJEKnUeVA+ZJaDeVq7C58HVHq2F7qzWQ7vIWWcH/9I=; b=Eiy8qoIw/+H+Jfx8mcv3/R1UdB2Av9PpBgReHTaaSLr7QNRpRxLq2Xr0kD7QHsDQLc jMqa1zT3VYLLajjYXGcTlBJkLplBff49xgT6WYc+qinCxPYmRcHZqFl1331GvJWLiTPM UMB3HWJWlGt64de9dAl0DBNGEudpy6kP1IT9QM35aydC9vFp3PaU8s3D433UtOgV09Wf USNkA1zZQqpuG59EIU44pHjzNmo61hM+1bBpTMMLERNSDAI0UV/88SjncVcabfNKo1SW OIYUccn9ZusVP6iipAYQiS29AeygpxEa6zqUL+91px6gBunwGQBepHO7GRI2Y+8/xJUM wjBw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=mLJEKnUeVA+ZJaDeVq7C58HVHq2F7qzWQ7vIWWcH/9I=; b=ARqVfzcIDC+2QP8x3EuzG7J5tBqk5WARKv5x1IZyyf1exlCH/qWnfohoyYrsqTwyfM +aOHp5FLSKy5nfyU+H6pV88IxMQJaLiMeIb37CvlzrbWnMawYQsYC+1XIn+guzEegSRc /8c59oWrF+12n/4p77G3nEXGxyWzlH1w47xK73D73ElwHSfnST7CtrrzJhbSh7mYuQVQ IXBVTsvmdX1FDUXStUjCT3+EBf5kAbI4ILJcNT05TzjmaSuGgIta5ERYYCTAkahsk26U S23vgAB154+GU4DjLRWPJkP+IUcGz7f7bquWcxmeDJ3Ql1icMUNVEQVOQOH2xOzY5BIx WPEA== X-Gm-Message-State: AOAM530ELy151prN41uKREjQYNA3Ksxg5TQuqAS3HdmoZFPed2mKTgYz vfeamzyPE4wdR43BQsZhRl86lw== X-Google-Smtp-Source: ABdhPJyznVD+crKQ6G6u0OsCozPGqZlakrH/5IfbsFoLhMCKNUnUBjBp31t4ativuEsftnsU7jqacA== X-Received: by 2002:a17:902:c401:b0:149:353c:9705 with SMTP id k1-20020a170902c40100b00149353c9705mr23328628plk.23.1640734736553; Tue, 28 Dec 2021 15:38:56 -0800 (PST) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id f7sm19397673pfc.141.2021.12.28.15.38.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 28 Dec 2021 15:38:56 -0800 (PST) Date: Tue, 28 Dec 2021 23:38:52 +0000 From: Sean Christopherson To: Jing Liu Cc: x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, pbonzini@redhat.com, corbet@lwn.net, shuah@kernel.org, jun.nakajima@intel.com, kevin.tian@intel.com, jing2.liu@linux.intel.com, guang.zeng@intel.com, wei.w.wang@intel.com, yang.zhong@intel.com Subject: Re: [PATCH v3 05/22] kvm: x86: Check permitted dynamic xfeatures at KVM_SET_CPUID2 Message-ID: References: <20211222124052.644626-1-jing2.liu@intel.com> <20211222124052.644626-6-jing2.liu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211222124052.644626-6-jing2.liu@intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org On Wed, Dec 22, 2021, Jing Liu wrote: > Guest xstate permissions should be set by userspace VMM before vcpu > creation. Extend KVM_SET_CPUID2 to verify that every feature reported > in CPUID[0xD] has proper permission set. Why? Nothing in the changelog, code, or comments explains why KVM _needs_ to prevent userspace from advertising bogus features to the guest. E.g. the virtual address width check exists because _KVM_ will do the wrong thing given a width other than 48 or 57, and explicity says as much in a comment.