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=-8.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 C6706C433E7 for ; Fri, 16 Oct 2020 10:21:50 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 4333920EDD for ; Fri, 16 Oct 2020 10:21:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="o1mH86nu" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4333920EDD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.7873.20761 (Exim 4.92) (envelope-from ) id 1kTMrZ-0002jK-2F; Fri, 16 Oct 2020 10:21:29 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 7873.20761; Fri, 16 Oct 2020 10:21:29 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kTMrY-0002jD-Uh; Fri, 16 Oct 2020 10:21:28 +0000 Received: by outflank-mailman (input) for mailman id 7873; Fri, 16 Oct 2020 10:21:27 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kTMrX-0002j8-Se for xen-devel@lists.xenproject.org; Fri, 16 Oct 2020 10:21:27 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 25006e1c-c1df-4e4f-ac89-c0ab42d59e66; Fri, 16 Oct 2020 10:21:26 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 928EBAEEF; Fri, 16 Oct 2020 10:21:25 +0000 (UTC) Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1kTMrX-0002j8-Se for xen-devel@lists.xenproject.org; Fri, 16 Oct 2020 10:21:27 +0000 X-Inumbo-ID: 25006e1c-c1df-4e4f-ac89-c0ab42d59e66 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 25006e1c-c1df-4e4f-ac89-c0ab42d59e66; Fri, 16 Oct 2020 10:21:26 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1602843685; h=from:from: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=qcmxnvRUtgd5pwtZDJYRsRYYJtUit4eLtWDDXvSIsZA=; b=o1mH86nuLG+oZiXBJ815ysRWI7MJTtTamFh18yR9aCNFHFbcni3mN3kW36LxDyGCP/0lPW YuEdYKoRkZZoaICvm3QkNswkEjnB0sQK0/LiyGr9ow2JI9E1NuoWKoXdC8Dfzn+nDcpSBI KnjwDh4sUmyRSYMXuRsIYBdY4mC3RAo= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 928EBAEEF; Fri, 16 Oct 2020 10:21:25 +0000 (UTC) Subject: Ping: [PATCH] x86/PV: make post-migration page state consistent From: Jan Beulich To: Andrew Cooper , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= Cc: "xen-devel@lists.xenproject.org" , Wei Liu References: Message-ID: Date: Fri, 16 Oct 2020 12:21:26 +0200 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 11.09.2020 12:34, Jan Beulich wrote: > When a page table page gets de-validated, its type reference count drops > to zero (and PGT_validated gets cleared), but its type remains intact. > XEN_DOMCTL_getpageframeinfo3, therefore, so far reported prior usage for > such pages. An intermediate write to such a page via e.g. > MMU_NORMAL_PT_UPDATE, however, would transition the page's type to > PGT_writable_page, thus altering what XEN_DOMCTL_getpageframeinfo3 would > return. In libxc the decision which pages to normalize / localize > depends solely on the type returned from the domctl. As a result without > further precautions the guest won't be able to tell whether such a page > has had its (apparent) PTE entries transitioned to the new MFNs. > > Add a check of PGT_validated, thus consistently avoiding normalization / > localization in the tool stack. > > Alongside using XEN_DOMCTL_PFINFO_NOTAB instead of plain zero for the > change at hand, also change the variable's initializer to use this > constant, too. Take the opportunity and also adjust its type. > > Signed-off-by: Jan Beulich I think I did address all questions here. Jan > --- a/xen/arch/x86/domctl.c > +++ b/xen/arch/x86/domctl.c > @@ -215,7 +215,8 @@ long arch_do_domctl( > > for ( i = 0; i < num; ++i ) > { > - unsigned long gfn = 0, type = 0; > + unsigned long gfn = 0; > + unsigned int type = XEN_DOMCTL_PFINFO_NOTAB; > struct page_info *page; > p2m_type_t t; > > @@ -255,6 +256,8 @@ long arch_do_domctl( > > if ( page->u.inuse.type_info & PGT_pinned ) > type |= XEN_DOMCTL_PFINFO_LPINTAB; > + else if ( !(page->u.inuse.type_info & PGT_validated) ) > + type = XEN_DOMCTL_PFINFO_NOTAB; > > if ( page->count_info & PGC_broken ) > type = XEN_DOMCTL_PFINFO_BROKEN; >