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=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, 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 D195BC433DB for ; Mon, 15 Mar 2021 09:57:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8821C64E99 for ; Mon, 15 Mar 2021 09:57:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229585AbhCOJ4t (ORCPT ); Mon, 15 Mar 2021 05:56:49 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:38442 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229518AbhCOJ43 (ORCPT ); Mon, 15 Mar 2021 05:56:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1615802189; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=s663/ZH1yFhPEvrM19sba3u1Bf1Jh6lElfvXAN6LRbo=; b=EP29WVvaO/rKTS+GsONWdpZfjDnnPl7b+YqDoPrULEaWwGQrMtmpTQBOdQpie3FGHZ043E I9LGHKaPuHGtu+Ou0GZa1Kf5uursz1JqVKbSTouNxaAYM5TstWx6Idu5rm/yzV+DMQKi2C 9YnWRZthFgPt2K3XofdQCV99zg6cfvc= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-23-hK3KDtw3MVGNr9lOM4Ywsw-1; Mon, 15 Mar 2021 05:56:25 -0400 X-MC-Unique: hK3KDtw3MVGNr9lOM4Ywsw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 4A57E802B45; Mon, 15 Mar 2021 09:56:23 +0000 (UTC) Received: from [10.64.54.175] (vpn2-54-175.bne.redhat.com [10.64.54.175]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CDF1B100239A; Mon, 15 Mar 2021 09:56:20 +0000 (UTC) Reply-To: Gavin Shan Subject: Re: [PATCH 4/4] KVM: arm64: Don't retrieve memory slot again in page fault handler To: Keqian Zhu , kvmarm@lists.cs.columbia.edu Cc: maz@kernel.org, will@kernel.org, linux-kernel@vger.kernel.org, shan.gavin@gmail.com References: <20210315041844.64915-1-gshan@redhat.com> <20210315041844.64915-5-gshan@redhat.com> <30073114-339f-33dd-0168-b4d6bfbe88bc@huawei.com> From: Gavin Shan Message-ID: <7a29ac43-ef11-e990-e08c-c5e97ea7d78d@redhat.com> Date: Mon, 15 Mar 2021 20:56:17 +1100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.0 MIME-Version: 1.0 In-Reply-To: <30073114-339f-33dd-0168-b4d6bfbe88bc@huawei.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Keqian, On 3/15/21 7:25 PM, Keqian Zhu wrote: > On 2021/3/15 12:18, Gavin Shan wrote: >> We needn't retrieve the memory slot again in user_mem_abort() because >> the corresponding memory slot has been passed from the caller. This > I think you are right, though fault_ipa will be adjusted when we try to use block mapping, > the fault_supports_stage2_huge_mapping() makes sure we're not trying to map anything > not covered by the memslot, so the adjusted fault_ipa still belongs to the memslot. > Yeah, it's correct. Besides, the @logging_active is determined based on the passed memory slot. It means user_mem_abort() can't support memory range which spans multiple memory slot. >> would save some CPU cycles. For example, the time used to write 1GB >> memory, which is backed by 2MB hugetlb pages and write-protected, is >> dropped by 6.8% from 928ms to 864ms. >> >> Signed-off-by: Gavin Shan >> --- >> arch/arm64/kvm/mmu.c | 5 +++-- >> 1 file changed, 3 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c >> index a5a8ade9fde4..4a4abcccfafb 100644 >> --- a/arch/arm64/kvm/mmu.c >> +++ b/arch/arm64/kvm/mmu.c >> @@ -846,7 +846,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, >> */ >> smp_rmb(); >> >> - pfn = gfn_to_pfn_prot(kvm, gfn, write_fault, &writable); >> + pfn = __gfn_to_pfn_memslot(memslot, gfn, false, NULL, >> + write_fault, &writable, NULL); > It's better to update the code comments at same time. > I guess you need some comments here? If so, I would add something like below in v2: /* * gfn_to_pfn_prot() can be used either with unnecessary overhead * introduced to locate the memory slot because the memory slot is * always fixed even @gfn is adjusted for huge pages. */ >> if (pfn == KVM_PFN_ERR_HWPOISON) { >> kvm_send_hwpoison_signal(hva, vma_shift); >> return 0; >> @@ -912,7 +913,7 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, >> /* Mark the page dirty only if the fault is handled successfully */ >> if (writable && !ret) { >> kvm_set_pfn_dirty(pfn); >> - mark_page_dirty(kvm, gfn); >> + mark_page_dirty_in_slot(kvm, memslot, gfn); >> } >> >> out_unlock: >> Thanks, Gavin