From patchwork Fri Apr 29 01:04:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sean Christopherson X-Patchwork-Id: 12831386 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 36E5AC4332F for ; Fri, 29 Apr 2022 01:04:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353755AbiD2BHt (ORCPT ); Thu, 28 Apr 2022 21:07:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34564 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353721AbiD2BHq (ORCPT ); Thu, 28 Apr 2022 21:07:46 -0400 Received: from mail-pf1-x44a.google.com (mail-pf1-x44a.google.com [IPv6:2607:f8b0:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1D73FBC874 for ; Thu, 28 Apr 2022 18:04:26 -0700 (PDT) Received: by mail-pf1-x44a.google.com with SMTP id x16-20020aa793b0000000b0050d3d5c4f4eso3513717pff.6 for ; Thu, 28 Apr 2022 18:04:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=reply-to:date:in-reply-to:message-id:mime-version:references :subject:from:to:cc; bh=Y7gKLvAp1p3RveznRBbFbm0Lo+y5YcSRX+jDV0xbRUg=; b=tWtOMpTlPqSbHAZ8AAAvm3vq0wYzfMiDS/xjibTVhQZwl1kosm21QeZ+m0cvPeadDt fKKRPAowcoyMjIM+O/pVXZ1bArrkezATPs9brXibFoXkyq62Zm0wcwh3ZJFQeTZw4NvP 7s8b61eNJ7GAYqThh3iPajH3arbG2tuEPBYSOHFhoA2/cwoS2lUHQPoJjn0Ayhqyne7y Dl5Puug2mvk711k/5Py9zES5RHwyuP71kCAakgimAS5doPEOqAL1c8AEzutoejzI97Q7 4xgVxMUmOansFxt8LR5869MwXRevwSQdWJwpNQ6n512AndjShI5uE+KGXYevcdH2s2z4 ii+Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:reply-to:date:in-reply-to:message-id :mime-version:references:subject:from:to:cc; bh=Y7gKLvAp1p3RveznRBbFbm0Lo+y5YcSRX+jDV0xbRUg=; b=f93cN0pAocd2j8JLEpRAhBlAj77/+1UjpdhpjuKMHnQAcAZTJW2BUpxiPlosLucjfq ZXVLHbK9efiiZSeJwh1G+OXCDJ+6K9pxfsMdCqqtmy6owhmIdRtmRu4GyLsaJ//ZwuVn em2Ga0AemddiwVNay0T7u6n+y8A24RtnND2NT/qeEtaVaCwSb2YHkamYqjsmDXEz2k8I Ie3A1Jglrn6N4qr75D+i0CUMD1h6oyaB+68nTDpDPzIMx6C40mGqeSFnfWN8QgfhZB0l TC9uUrozVIdcuQZ2evqVhWtqa2x5b1on0litrQ+tqFNmv5xDaWeSzV7oaNKKPqCnz+LS dFFw== X-Gm-Message-State: AOAM533IKtTw7lxqrsdfFrZk7i+BMsI0THIsRnBA1R+hv1sO8EkMW8U9 yJATXJ3Go8DJF6HA4u2pbYq9arRvmkE= X-Google-Smtp-Source: ABdhPJwu72FzzFGpQThtNokReT4b9ApF02OAzwe9Fv4hC2B6uwlF5JMCh5iypRnr5EbK1PvBsiUXjY6rPNw= X-Received: from seanjc.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:3e5]) (user=seanjc job=sendgmr) by 2002:a17:90b:1e4e:b0:1da:3936:dc2e with SMTP id pi14-20020a17090b1e4e00b001da3936dc2emr1146759pjb.20.1651194265530; Thu, 28 Apr 2022 18:04:25 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 29 Apr 2022 01:04:10 +0000 In-Reply-To: <20220429010416.2788472-1-seanjc@google.com> Message-Id: <20220429010416.2788472-5-seanjc@google.com> Mime-Version: 1.0 References: <20220429010416.2788472-1-seanjc@google.com> X-Mailer: git-send-email 2.36.0.464.gb9c8b46e94-goog Subject: [PATCH 04/10] KVM: Avoid pfn_to_page() and vice versa when releasing pages From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Invert the order of KVM's page/pfn release helpers so that the "inner" helper operates on a page instead of a pfn. As pointed out by Linus[*], converting between struct page and a pfn isn't necessarily cheap, and that's not even counting the overhead of is_error_noslot_pfn() and kvm_is_reserved_pfn(). Even if the checks were dirt cheap, there's no reason to convert from a page to a pfn and back to a page, just to mark the page dirty/accessed or to put a reference to the page. Opportunistically drop a stale declaration of kvm_set_page_accessed() from kvm_host.h (there was no implementation). No functional change intended. [*] https://lore.kernel.org/all/CAHk-=wifQimj2d6npq-wCi5onYPjzQg4vyO4tFcPJJZr268cRw@mail.gmail.com Signed-off-by: Sean Christopherson --- include/linux/kvm_host.h | 1 - virt/kvm/kvm_main.c | 58 +++++++++++++++++++++++++--------------- 2 files changed, 37 insertions(+), 22 deletions(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 252ee4a61b58..e32fbde79298 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -1116,7 +1116,6 @@ unsigned long gfn_to_hva_memslot_prot(struct kvm_memory_slot *slot, gfn_t gfn, bool *writable); void kvm_release_page_clean(struct page *page); void kvm_release_page_dirty(struct page *page); -void kvm_set_page_accessed(struct page *page); kvm_pfn_t gfn_to_pfn(struct kvm *kvm, gfn_t gfn); kvm_pfn_t gfn_to_pfn_prot(struct kvm *kvm, gfn_t gfn, bool write_fault, diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 46d12998732e..ab7549195c68 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2798,18 +2798,40 @@ struct page *kvm_vcpu_gfn_to_page(struct kvm_vcpu *vcpu, gfn_t gfn) } EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_page); +static bool kvm_is_ad_tracked_page(struct page *page) +{ + /* + * Per page-flags.h, pages tagged PG_reserved "should in general not be + * touched (e.g. set dirty) except by its owner". + */ + return !PageReserved(page); +} + +static void kvm_set_page_dirty(struct page *page) +{ + if (kvm_is_ad_tracked_page(page)) + SetPageDirty(page); +} + +static void kvm_set_page_accessed(struct page *page) +{ + if (kvm_is_ad_tracked_page(page)) + mark_page_accessed(page); +} + void kvm_release_page_clean(struct page *page) { WARN_ON(is_error_page(page)); - kvm_release_pfn_clean(page_to_pfn(page)); + kvm_set_page_accessed(page); + put_page(page); } EXPORT_SYMBOL_GPL(kvm_release_page_clean); void kvm_release_pfn_clean(kvm_pfn_t pfn) { if (!is_error_noslot_pfn(pfn) && !kvm_is_reserved_pfn(pfn)) - put_page(pfn_to_page(pfn)); + kvm_release_page_clean(pfn_to_page(pfn)); } EXPORT_SYMBOL_GPL(kvm_release_pfn_clean); @@ -2817,40 +2839,34 @@ void kvm_release_page_dirty(struct page *page) { WARN_ON(is_error_page(page)); - kvm_release_pfn_dirty(page_to_pfn(page)); + kvm_set_page_dirty(page); + kvm_release_page_clean(page); } EXPORT_SYMBOL_GPL(kvm_release_page_dirty); void kvm_release_pfn_dirty(kvm_pfn_t pfn) { - kvm_set_pfn_dirty(pfn); - kvm_release_pfn_clean(pfn); + if (!is_error_noslot_pfn(pfn) && !kvm_is_reserved_pfn(pfn)) + kvm_release_page_dirty(pfn_to_page(pfn)); } EXPORT_SYMBOL_GPL(kvm_release_pfn_dirty); -static bool kvm_is_ad_tracked_pfn(kvm_pfn_t pfn) -{ - if (!pfn_valid(pfn)) - return false; - - /* - * Per page-flags.h, pages tagged PG_reserved "should in general not be - * touched (e.g. set dirty) except by its owner". - */ - return !PageReserved(pfn_to_page(pfn)); -} - +/* + * Note, checking for an error/noslot pfn is the caller's responsibility when + * directly marking a page dirty/accessed. Unlike the "release" helpers, the + * "set" helpers are not to be unused when the pfn might point at garbage. + */ void kvm_set_pfn_dirty(kvm_pfn_t pfn) { - if (kvm_is_ad_tracked_pfn(pfn)) - SetPageDirty(pfn_to_page(pfn)); + if (pfn_valid(pfn)) + kvm_set_page_dirty(pfn_to_page(pfn)); } EXPORT_SYMBOL_GPL(kvm_set_pfn_dirty); void kvm_set_pfn_accessed(kvm_pfn_t pfn) { - if (kvm_is_ad_tracked_pfn(pfn)) - mark_page_accessed(pfn_to_page(pfn)); + if (pfn_valid(pfn)) + kvm_set_page_accessed(pfn_to_page(pfn)); } EXPORT_SYMBOL_GPL(kvm_set_pfn_accessed);