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=-11.2 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=unavailable 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 DE3A0C388F9 for ; Tue, 27 Oct 2020 22:46:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A5038221F7 for ; Tue, 27 Oct 2020 22:46:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757411AbgJ0Wqy (ORCPT ); Tue, 27 Oct 2020 18:46:54 -0400 Received: from mga14.intel.com ([192.55.52.115]:61049 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757005AbgJ0Wqy (ORCPT ); Tue, 27 Oct 2020 18:46:54 -0400 IronPort-SDR: aHjAdtHLbS3vskDut7odSVwp+STR+1m1m0A+bOXr/rhxfsJQG95qa/64fvjk2qQHXe636tMlf/ CTtIOFlT2VQg== X-IronPort-AV: E=McAfee;i="6000,8403,9787"; a="167394579" X-IronPort-AV: E=Sophos;i="5.77,424,1596524400"; d="scan'208";a="167394579" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Oct 2020 15:46:53 -0700 IronPort-SDR: 8z6ByX/oX8TRbo3l/vwgrZtSk6jRDG9uCION1zqZAuCf13rRqSvpf2x6JlC0jW99l4kfhLJ5st VD+5ATXxREHw== X-IronPort-AV: E=Sophos;i="5.77,424,1596524400"; d="scan'208";a="355715662" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.160]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Oct 2020 15:46:53 -0700 Date: Tue, 27 Oct 2020 15:46:52 -0700 From: Sean Christopherson To: Ben Gardon Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm , LKML Subject: Re: [PATCH 1/3] KVM: x86/mmu: Add helper macro for computing hugepage GFN mask Message-ID: <20201027224652.GB2011@linux.intel.com> References: <20201027214300.1342-1-sean.j.christopherson@intel.com> <20201027214300.1342-2-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Oct 27, 2020 at 03:17:40PM -0700, Ben Gardon wrote: > On Tue, Oct 27, 2020 at 2:43 PM Sean Christopherson > wrote: > > > > Add a helper to compute the GFN mask given a hugepage level, KVM is > > accumulating quite a few users with the addition of the TDP MMU. > > > > Note, gcc is clever enough to use a single NEG instruction instead of > > SUB+NOT, i.e. use the more common "~(level -1)" pattern instead of > > round_gfn_for_level()'s direct two's complement trickery. > > As far as I can tell this patch has no functional changes intended. > Please correct me if that's not correct. Correct. :-) > > > > Signed-off-by: Sean Christopherson > > Reviewed-by: Ben Gardon > > > --- > > arch/x86/include/asm/kvm_host.h | 1 + > > arch/x86/kvm/mmu/mmu.c | 2 +- > > arch/x86/kvm/mmu/paging_tmpl.h | 4 ++-- > > arch/x86/kvm/mmu/tdp_iter.c | 2 +- > > 4 files changed, 5 insertions(+), 4 deletions(-) > > > > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > > index d44858b69353..6ea046415f29 100644 > > --- a/arch/x86/include/asm/kvm_host.h > > +++ b/arch/x86/include/asm/kvm_host.h > > @@ -119,6 +119,7 @@ > > #define KVM_HPAGE_SIZE(x) (1UL << KVM_HPAGE_SHIFT(x)) > > #define KVM_HPAGE_MASK(x) (~(KVM_HPAGE_SIZE(x) - 1)) > > #define KVM_PAGES_PER_HPAGE(x) (KVM_HPAGE_SIZE(x) / PAGE_SIZE) > > +#define KVM_HPAGE_GFN_MASK(x) (~(KVM_PAGES_PER_HPAGE(x) - 1)) > > NIT: I know x follows the convention on adjacent macros, but this > would be clearer to me if x was changed to level. (Probably for all > the macros in this block) Agreed. I'll spin a v2 and opportunistically change them all to "level" in this patch. I'll also add "No function change intended™." to patches 1 and 3. > > static inline gfn_t gfn_to_index(gfn_t gfn, gfn_t base_gfn, int level) > > {