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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 69890C0044C for ; Wed, 31 Oct 2018 14:36:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 219AE205F4 for ; Wed, 31 Oct 2018 14:36:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 219AE205F4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729575AbeJaXfG (ORCPT ); Wed, 31 Oct 2018 19:35:06 -0400 Received: from foss.arm.com ([217.140.101.70]:41982 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729494AbeJaXfG (ORCPT ); Wed, 31 Oct 2018 19:35:06 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id E67AB341; Wed, 31 Oct 2018 07:36:48 -0700 (PDT) Received: from localhost (e113682-lin.copenhagen.arm.com [10.32.144.41]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 4DB4F3F71D; Wed, 31 Oct 2018 07:36:48 -0700 (PDT) Date: Wed, 31 Oct 2018 15:36:46 +0100 From: Christoffer Dall To: Punit Agrawal Cc: kvmarm@lists.cs.columbia.edu, marc.zyngier@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, suzuki.poulose@arm.com, stable@vger.kernel.org Subject: Re: [PATCH v8 1/9] KVM: arm/arm64: Ensure only THP is candidate for adjustment Message-ID: <20181031143646.GE12057@e113682-lin.lund.arm.com> References: <20181001155443.23032-1-punit.agrawal@arm.com> <20181001155443.23032-2-punit.agrawal@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181001155443.23032-2-punit.agrawal@arm.com> 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 Mon, Oct 01, 2018 at 04:54:35PM +0100, Punit Agrawal wrote: > PageTransCompoundMap() returns true for hugetlbfs and THP > hugepages. This behaviour incorrectly leads to stage 2 faults for > unsupported hugepage sizes (e.g., 64K hugepage with 4K pages) to be > treated as THP faults. > > Tighten the check to filter out hugetlbfs pages. This also leads to > consistently mapping all unsupported hugepage sizes as PTE level > entries at stage 2. > > Signed-off-by: Punit Agrawal > Reviewed-by: Suzuki Poulose > Cc: Christoffer Dall > Cc: Marc Zyngier > Cc: stable@vger.kernel.org # v4.13+ Hmm, this function is only actually called from user_mem_abort() if we have (!hugetlb), so I'm not sure the cc stable here was actually warranted, nor that this patch is strictly necessary. It doesn't hurt, and makes the code potentially more robust for the future though. Am I missing something? Thanks, Christoffer > --- > virt/kvm/arm/mmu.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/virt/kvm/arm/mmu.c b/virt/kvm/arm/mmu.c > index 7e477b3cae5b..c23a1b323aad 100644 > --- a/virt/kvm/arm/mmu.c > +++ b/virt/kvm/arm/mmu.c > @@ -1231,8 +1231,14 @@ static bool transparent_hugepage_adjust(kvm_pfn_t *pfnp, phys_addr_t *ipap) > { > kvm_pfn_t pfn = *pfnp; > gfn_t gfn = *ipap >> PAGE_SHIFT; > + struct page *page = pfn_to_page(pfn); > > - if (PageTransCompoundMap(pfn_to_page(pfn))) { > + /* > + * PageTransCompoungMap() returns true for THP and > + * hugetlbfs. Make sure the adjustment is done only for THP > + * pages. > + */ > + if (!PageHuge(page) && PageTransCompoundMap(page)) { > unsigned long mask; > /* > * The address we faulted on is backed by a transparent huge > -- > 2.18.0 >