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=-11.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 CF757C2D0A8 for ; Mon, 28 Sep 2020 16:24:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8B6C2206DB for ; Mon, 28 Sep 2020 16:24:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726716AbgI1QYV (ORCPT ); Mon, 28 Sep 2020 12:24:21 -0400 Received: from mga06.intel.com ([134.134.136.31]:39065 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726380AbgI1QYV (ORCPT ); Mon, 28 Sep 2020 12:24:21 -0400 IronPort-SDR: tsYigJ/F0UdptpI9nXmnkp652Sx6/furKMmeTq6+4GdZhIf4O289BHlQtqEb+v2QyjRqCCxTBQ YPI/TVb0adLQ== X-IronPort-AV: E=McAfee;i="6000,8403,9758"; a="223616540" X-IronPort-AV: E=Sophos;i="5.77,313,1596524400"; d="scan'208";a="223616540" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Sep 2020 09:24:19 -0700 IronPort-SDR: 1B3FE5vxGxHDeo79fUzTdH701ulI1W71N0yQ7ZH2M/l8Jtp3tvjTy0+zzrcY/tULOJ84elq+9I 8cig0uxH6gsQ== X-IronPort-AV: E=Sophos;i="5.77,313,1596524400"; d="scan'208";a="350781290" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.160]) by orsmga007-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 28 Sep 2020 09:24:18 -0700 Date: Mon, 28 Sep 2020 09:24:17 -0700 From: Sean Christopherson To: Lai Jiangshan Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Lai Jiangshan , Yu Zhang , Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" Subject: Re: [RFC PATCH 1/2] kvm/x86: intercept guest changes to X86_CR4_LA57 Message-ID: <20200928162417.GA28825@linux.intel.com> References: <20200928083047.3349-1-jiangshanlai@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200928083047.3349-1-jiangshanlai@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 28, 2020 at 04:30:46PM +0800, Lai Jiangshan wrote: > From: Lai Jiangshan > > When shadowpaping is enabled, guest should not be allowed > to toggle X86_CR4_LA57. And X86_CR4_LA57 is a rarely changed > bit, so we can just intercept all the attempts to toggle it > no matter shadowpaping is in used or not. > > Fixes: fd8cb433734ee ("KVM: MMU: Expose the LA57 feature to VM.") > Cc: Sean Christopherson > Cc: Yu Zhang > Cc: Paolo Bonzini > Signed-off-by: Lai Jiangshan > --- > No test to toggle X86_CR4_LA57 in guest since I can't access to > any CPU supports it. Maybe it is not a real problem. LA57 doesn't need to be intercepted. It can't be toggled in 64-bit mode (causes a #GP), and it's ignored in 32-bit mode. That means LA57 can only take effect when 64-bit mode is enabled, at which time KVM will update its MMU context accordingly. > arch/x86/kvm/kvm_cache_regs.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/kvm_cache_regs.h b/arch/x86/kvm/kvm_cache_regs.h > index cfe83d4ae625..ca0781b41df9 100644 > --- a/arch/x86/kvm/kvm_cache_regs.h > +++ b/arch/x86/kvm/kvm_cache_regs.h > @@ -7,7 +7,7 @@ > #define KVM_POSSIBLE_CR0_GUEST_BITS X86_CR0_TS > #define KVM_POSSIBLE_CR4_GUEST_BITS \ > (X86_CR4_PVI | X86_CR4_DE | X86_CR4_PCE | X86_CR4_OSFXSR \ > - | X86_CR4_OSXMMEXCPT | X86_CR4_LA57 | X86_CR4_PGE | X86_CR4_TSD) > + | X86_CR4_OSXMMEXCPT | X86_CR4_PGE | X86_CR4_TSD) > > #define BUILD_KVM_GPR_ACCESSORS(lname, uname) \ > static __always_inline unsigned long kvm_##lname##_read(struct kvm_vcpu *vcpu)\ > -- > 2.19.1.6.gb485710b >