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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 1E490C433E1 for ; Thu, 11 Jun 2020 15:44:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 02DD2206DC for ; Thu, 11 Jun 2020 15:44:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728683AbgFKPoA (ORCPT ); Thu, 11 Jun 2020 11:44:00 -0400 Received: from mga03.intel.com ([134.134.136.65]:40538 "EHLO mga03.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728496AbgFKPn7 (ORCPT ); Thu, 11 Jun 2020 11:43:59 -0400 IronPort-SDR: zVbYBjCm+9L7CvMejLIsQdTToMqnSAR/RHJ4NnfDXDmHKrJaHs392+3+drFf0F4Cv2P1+NSZnB los2p04MIFKQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by orsmga103.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Jun 2020 08:43:59 -0700 IronPort-SDR: +Ydw/4Fg05XSUVeVdaVnYwXl169Eie8ePVgfFpQAiQZ2NUmXKZaRvV2IeZsKgMR2pcPAaKpDpn +n8lSwG3SLOg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,499,1583222400"; d="scan'208";a="419144435" Received: from sjchrist-coffee.jf.intel.com (HELO linux.intel.com) ([10.54.74.152]) by orsmga004.jf.intel.com with ESMTP; 11 Jun 2020 08:43:59 -0700 Date: Thu, 11 Jun 2020 08:43:59 -0700 From: Sean Christopherson To: Marc Zyngier Cc: Paul Mackerras , Christian Borntraeger , Janosch Frank , Paolo Bonzini , James Morse , Julien Thierry , Suzuki K Poulose , David Hildenbrand , Cornelia Huck , Claudio Imbrenda , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, linux-mips@vger.kernel.org, kvm@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org, Peter Feiner , Peter Shier , Junaid Shahid , Ben Gardon , Christoffer Dall Subject: Re: [PATCH 17/21] KVM: arm64: Use common code's approach for __GFP_ZERO with memory caches Message-ID: <20200611154359.GF29918@linux.intel.com> References: <20200605213853.14959-1-sean.j.christopherson@intel.com> <20200605213853.14959-18-sean.j.christopherson@intel.com> <6cc08074c289cbea7b9c1deeaf18c63f@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <6cc08074c289cbea7b9c1deeaf18c63f@kernel.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 11, 2020 at 08:59:05AM +0100, Marc Zyngier wrote: > >diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > >index 9398b66f8a87..688213ef34f0 100644 > >--- a/arch/arm64/kvm/mmu.c > >+++ b/arch/arm64/kvm/mmu.c > >@@ -131,7 +131,8 @@ static int mmu_topup_memory_cache(struct > >kvm_mmu_memory_cache *cache, int min) > > if (cache->nobjs >= min) > > return 0; > > while (cache->nobjs < ARRAY_SIZE(cache->objects)) { > >- page = (void *)__get_free_page(GFP_PGTABLE_USER); > >+ page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT | > > This is definitely a change in the way we account for guest > page tables allocation, although I find it bizarre that not > all architectures account for it the same way. It's not intended to be a functional change, i.e. the allocations should still be accounted: #define GFP_PGTABLE_USER (GFP_PGTABLE_KERNEL | __GFP_ACCOUNT) | -> #define GFP_PGTABLE_KERNEL (GFP_KERNEL | __GFP_ZERO) == GFP_KERNEL | __GFP_ACCOUNT | __GFP_ZERO versus #define GFP_KERNEL_ACCOUNT (GFP_KERNEL | __GFP_ACCOUNT) with __GFP_ZERO explicitly OR'd in == GFP_KERNEL | __GFP_ACCOUNT | __GFP_ZERO I can put the above in the changelog, unless of course it's wrong and I've missed something. > It seems logical to me that nested page tables would be accounted > against userspace, but I'm willing to be educated on the matter. > > Another possibility is that depending on the context, some allocations > should be accounted on either the kernel or userspace (NV on arm64 > could definitely do something like that). If that was the case, > maybe moving most of the GFP_* flags into the per-cache flags, > and have the renaming that Ben suggested earlier. > > Thanks, > > M. > -- > Jazz is not dead. It just smells funny...