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 3ED3BC4332F for ; Wed, 21 Dec 2022 08:23:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229623AbiLUIXJ (ORCPT ); Wed, 21 Dec 2022 03:23:09 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52652 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229612AbiLUIXG (ORCPT ); Wed, 21 Dec 2022 03:23:06 -0500 Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE2DFF5F for ; Wed, 21 Dec 2022 00:23:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1671610985; x=1703146985; h=message-id:subject:from:to:cc:date:in-reply-to: references:mime-version:content-transfer-encoding; bh=Mgjs1xSF08jGDm1gXUek4CDRj3pUifX25AjEWLPyfww=; b=Y6xiuK/Ba10oVo+JNIctfPlbIlzE7NccqA5hgGIjBemz3InfxDH2wfnL Nv8bElQJY5zsN/xVuiYkzbcSGmi1u1zVIQ9xxiqKdAOZvISIMANNQlEIs zEzAHo0IySckgzdOPONLaOKzAFTr6FE3Tvr4Y+QtZva/rchXzMOz42XuI IgHOCyy1orWfuuT8WRuauhCvoxF0B1wfdO5VpkxNP5tdzD/Bu9+Fo+1X9 8asaIb+I8N7jRjDW5FFqROYTQfc4pwItY43h1/Zw8GOOpSRgEdOhR/d9h 398isoQNpAWnttc4mx7u2iHhAb9qNT5e85ocEn31J0S056Jbpd9ku6adK Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10567"; a="321728446" X-IronPort-AV: E=Sophos;i="5.96,262,1665471600"; d="scan'208";a="321728446" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Dec 2022 00:22:46 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10567"; a="740093308" X-IronPort-AV: E=Sophos;i="5.96,262,1665471600"; d="scan'208";a="740093308" Received: from sqa-gate.sh.intel.com (HELO robert-ivt.tsp.org) ([10.239.48.212]) by FMSMGA003.fm.intel.com with ESMTP; 21 Dec 2022 00:22:34 -0800 Message-ID: <99219ca2f5b0fdb2daa825374235a0b05b74724f.camel@linux.intel.com> Subject: Re: [PATCH v3 6/9] KVM: x86: Untag LAM bits when applicable From: Robert Hoo To: Yuan Yao Cc: pbonzini@redhat.com, seanjc@google.com, kirill.shutemov@linux.intel.com, kvm@vger.kernel.org, Jingqi Liu Date: Wed, 21 Dec 2022 16:22:33 +0800 In-Reply-To: <20221221025527.jbsordepwfytdwmx@yy-desk-7060> References: <20221209044557.1496580-1-robert.hu@linux.intel.com> <20221209044557.1496580-7-robert.hu@linux.intel.com> <20221221025527.jbsordepwfytdwmx@yy-desk-7060> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-10.el7) Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, 2022-12-21 at 10:55 +0800, Yuan Yao wrote: > > +#ifdef CONFIG_X86_64 > > +/* untag addr for guest, according to vCPU CR3 and CR4 settings */ > > +static inline u64 kvm_untagged_addr(u64 addr, struct kvm_vcpu > > *vcpu) > > +{ > > + if (addr >> 63 == 0) { > > + /* User pointers */ > > + if (kvm_read_cr3(vcpu) & X86_CR3_LAM_U57) > > + addr = get_canonical(addr, 57); > > + else if (kvm_read_cr3(vcpu) & X86_CR3_LAM_U48) { > > + /* > > + * If guest enabled 5-level paging and LAM_U48, > > + * bit 47 should be 0, bit 48:56 contains meta > > data > > + * although bit 47:56 are valid 5-level address > > + * bits. > > + * If LAM_U48 and 4-level paging, bit47 is 0. > > + */ > > + WARN_ON(addr & _BITUL(47)); > > IIUC, LAM_47 userspace canonical checking rule requests "bit 63 == > bit 47 == 0" > before sign-extened the address. > > if so looks it's guest's fault to not follow the LAM canonical > checking rule, > what's the behavior of such violation on bare metal, #GP ? Spec (ISE 10.2) doesn't mention a #GP for this case. IIUC, those overlap bits are zeroed. Current native Kernel LAM only enables LAM_U57. > The behavior > shuld be same for guest instead of WARN_ON() on host, host does > nothing wrong. > Agree that host did nothing wrong. So remove WARN_ON(), use a pr_warn() instead? I here meant to warn that such case happens.