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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 CAB3AC282DD for ; Fri, 10 Jan 2020 16:13:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9700E20673 for ; Fri, 10 Jan 2020 16:13:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728616AbgAJQNa convert rfc822-to-8bit (ORCPT ); Fri, 10 Jan 2020 11:13:30 -0500 Received: from eu-smtp-delivery-151.mimecast.com ([207.82.80.151]:31069 "EHLO eu-smtp-delivery-151.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728397AbgAJQNa (ORCPT ); Fri, 10 Jan 2020 11:13:30 -0500 Received: from AcuMS.aculab.com (156.67.243.126 [156.67.243.126]) (Using TLS) by relay.mimecast.com with ESMTP id uk-mta-132-FDBerwKtMMiqDv2bYc1W-w-1; Fri, 10 Jan 2020 16:13:26 +0000 Received: from AcuMS.Aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) by AcuMS.aculab.com (fd9f:af1c:a25b:0:43c:695e:880f:8750) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Fri, 10 Jan 2020 16:13:25 +0000 Received: from AcuMS.Aculab.com ([fe80::43c:695e:880f:8750]) by AcuMS.aculab.com ([fe80::43c:695e:880f:8750%12]) with mapi id 15.00.1347.000; Fri, 10 Jan 2020 16:13:25 +0000 From: David Laight To: 'Sean Christopherson' , Vitaly Kuznetsov CC: Paolo Bonzini , Wanpeng Li , Jim Mattson , Joerg Roedel , "kvm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Arvind Sankar Subject: RE: [PATCH v2 2/2] KVM: x86/mmu: Micro-optimize nEPT's bad memptype/XWR checks Thread-Topic: [PATCH v2 2/2] KVM: x86/mmu: Micro-optimize nEPT's bad memptype/XWR checks Thread-Index: AQHVx8+0looGh+atVEOWwxZzFZ77z6fkEXjg Date: Fri, 10 Jan 2020 16:13:25 +0000 Message-ID: References: <20200109230640.29927-1-sean.j.christopherson@intel.com> <20200109230640.29927-3-sean.j.christopherson@intel.com> <878smfr18i.fsf@vitty.brq.redhat.com> <20200110160453.GA21485@linux.intel.com> In-Reply-To: <20200110160453.GA21485@linux.intel.com> Accept-Language: en-GB, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-MC-Unique: FDBerwKtMMiqDv2bYc1W-w-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sean Christopherson > Sent: 10 January 2020 16:05 ... > Similar to your suggestion, but it avoids evaluating __is_bad_mt_xwr() if > reserved bits are set, which is admittedly rare. > > return __is_rsvd_bits_set(&mmu->guest_rsvd_check, gpte, level) > #if PTTYPE == PTTYPE_EPT > || __is_bad_mt_xwr(&mmu->guest_rsvd_check, gpte) > #endif > ; Or: return __is_rsvd_bits_set(&mmu->guest_rsvd_check, gpte, level) || (PTTYPE == PTTYPE_EPT && __is_bad_mt_xwr(&mmu->guest_rsvd_check, gpte)); Relying in the compiler to optimise it away. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)