From patchwork Thu Feb 25 09:53:43 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 387644 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=-18.8 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, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT 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 692DBC433DB for ; Thu, 25 Feb 2021 09:59:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0D7C864F06 for ; Thu, 25 Feb 2021 09:59:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234469AbhBYJ6z (ORCPT ); Thu, 25 Feb 2021 04:58:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:34226 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235601AbhBYJ4q (ORCPT ); Thu, 25 Feb 2021 04:56:46 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 048B664F12; Thu, 25 Feb 2021 09:54:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614246867; bh=UEDpM2iNq1Jh298bEQH9lI2lZIkdVnRfLGHTU/RCeyE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1LbII0DNa6xFsmVvp8/WvfEadQvdCuoC0KdqHPR4W03PmfI3340uIzyCp7ZHfmeYL 6wMAZmYdO2d42VYC8SiWihflvW1tSIPRFhUX5q/OlToAxI52BJn4nXBPa++RuLqrmi tA//1ZEBt5NmCOu6l4pqbICXcMIBaJ4xUhBLC5lE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zdenek Kaspar , Sean Christopherson , Paolo Bonzini Subject: [PATCH 5.11 09/12] KVM: x86: Zap the oldest MMU pages, not the newest Date: Thu, 25 Feb 2021 10:53:43 +0100 Message-Id: <20210225092515.434032433@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210225092515.015261674@linuxfoundation.org> References: <20210225092515.015261674@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sean Christopherson commit 8fc517267fb28576dfca2380cc2497a2454b8fae upstream. Walk the list of MMU pages in reverse in kvm_mmu_zap_oldest_mmu_pages(). The list is FIFO, meaning new pages are inserted at the head and thus the oldest pages are at the tail. Using a "forward" iterator causes KVM to zap MMU pages that were just added, which obliterates guest performance once the max number of shadow MMU pages is reached. Fixes: 6b82ef2c9cf1 ("KVM: x86/mmu: Batch zap MMU pages when recycling oldest pages") Reported-by: Zdenek Kaspar Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-Id: <20210113205030.3481307-1-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/mmu/mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -2417,7 +2417,7 @@ static unsigned long kvm_mmu_zap_oldest_ return 0; restart: - list_for_each_entry_safe(sp, tmp, &kvm->arch.active_mmu_pages, link) { + list_for_each_entry_safe_reverse(sp, tmp, &kvm->arch.active_mmu_pages, link) { /* * Don't zap active root pages, the page itself can't be freed * and zapping it will just force vCPUs to realloc and reload.