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 E95BBC43334 for ; Tue, 28 Jun 2022 01:38:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S243178AbiF1BiX (ORCPT ); Mon, 27 Jun 2022 21:38:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S243168AbiF1BiX (ORCPT ); Mon, 27 Jun 2022 21:38:23 -0400 Received: from mail-pj1-x102b.google.com (mail-pj1-x102b.google.com [IPv6:2607:f8b0:4864:20::102b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 638381B7AD for ; Mon, 27 Jun 2022 18:38:22 -0700 (PDT) Received: by mail-pj1-x102b.google.com with SMTP id g20-20020a17090a579400b001ed52939d72so5677480pji.4 for ; Mon, 27 Jun 2022 18:38:22 -0700 (PDT) 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=qur+4N7rCs+mVR7/NYYv8k082l5ZRw3E/FtSDC7Vi20=; b=Es9RG3ilIwqewAskEs5xAWk7WPS179OJkjmrE1lpHCMqiMtUcmvTcsncMX9uv2+3St Cfg+MLs9G1Q1U+AWTwVOeOQs9jFh0b17GEhcbOLZa0mEV1InvlB8BS4sS6ppgnRBVedv t2hGAdnM7xWa5f8gf2Ohyu4expuS2Y9Dne2L018kAf4S+l0RHMu4SYG4AVSXhANglTAb iZ0b2CdJLCf34hwJPMzNtgHz7T+2o4RsEUwxxwSqqX+Eln24p0BJwVzo72bJl9r7qJGV 1qoc1BSP7QwLF10YHsOHM2hnb5nha47ddiysJf28h9CIkIEAdpN0l1bBizKHVCBsVrjy 3Vdw== 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=qur+4N7rCs+mVR7/NYYv8k082l5ZRw3E/FtSDC7Vi20=; b=mYj1VMH5rFfKHJhRAhXctH1Cfl2wM8Rf/Y141NhO8CFneSYHegIPIEsoIOmJhV/vdq cnI7YOGieQ53EvRVYVc+zXu+mA8+/pwLyilY4JEVfUGTQaehOzamqHfqWDGOmOCf9BCH 2DuQC4+23F+gYnRMUcAefiLcyYbmXpMYpXwhTJZyhQndiNB7/DZ33woUTTAikjMEN7pv 6DDTFkVoOsgJD+tIw731EVIdoSXIKit4MLypsvCaOfR3WWogG2V0Ql74JcOiFar9dZbm m3wCfZrrl8/y7NVgLJRJ0RPdpmwAgHon9AtlJhXMgN3zYkcDW8TQatUKjUlS696fjFMI COPA== X-Gm-Message-State: AJIora8SiPCuSjRS6+5F0tWWLOPI3j+LdSzOE0Kecd24+upb5bF2bUDa 87i2wLX5GchTQ8ULfa/I0eQSOw== X-Google-Smtp-Source: AGRyM1tOjbhqovgiABjLCosAQ6d3Mxq9yIbjrj8W8Cwt5EgLooPUzzbVxvgAiu8u0rT87yiKJU5Kqg== X-Received: by 2002:a17:90b:3685:b0:1ec:f6f4:8a64 with SMTP id mj5-20020a17090b368500b001ecf6f48a64mr24720404pjb.199.1656380301657; Mon, 27 Jun 2022 18:38:21 -0700 (PDT) Received: from google.com (123.65.230.35.bc.googleusercontent.com. [35.230.65.123]) by smtp.gmail.com with ESMTPSA id a14-20020a1709027d8e00b0016b7ba73a18sm2958838plm.38.2022.06.27.18.38.20 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 27 Jun 2022 18:38:20 -0700 (PDT) Date: Tue, 28 Jun 2022 01:38:17 +0000 From: Sean Christopherson To: "Dong, Eddie" Cc: Vitaly Kuznetsov , "kvm@vger.kernel.org" , Paolo Bonzini , Anirudh Rayabharam , Wanpeng Li , Jim Mattson , Maxim Levitsky , "linux-hyperv@vger.kernel.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 04/14] KVM: VMX: Extend VMX controls macro shenanigans Message-ID: References: <20220627160440.31857-1-vkuznets@redhat.com> <20220627160440.31857-5-vkuznets@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org On Mon, Jun 27, 2022, Dong, Eddie wrote: > > static inline void lname##_controls_clearbit(struct vcpu_vmx *vmx, u##bits > > val) \ > > { > > \ > > + BUILD_BUG_ON(!(val & (KVM_REQ_VMX_##uname | > > KVM_OPT_VMX_##uname))); \ > > lname##_controls_set(vmx, lname##_controls_get(vmx) & ~val); > > \ > > } > > With this, will it be safer if we present L1 CTRL MSRs with the bits KVM > really uses? Do I miss something? KVM will still allow L1 to use features/controls that KVM itself doesn't use, but exposing features/controls that KVM doesn't use will require a more explicit "override" of sorts, e.g. to prevent advertising features that are supported in hardware, known to KVM, but disabled for whatever reason, e.g. a CPU bug, eVMCS incompatibility, module param, etc... The intent of this BUILD_BUG_ON() is to detect KVM usage of bits that aren't enabled by default, i.e. to lower the probability that a control gets used by KVM but isn't exposed to L1 because it's a dynamically enabled control.