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=-12.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,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 CF61AC433DB for ; Fri, 19 Mar 2021 11:26:34 +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 8510864F6D for ; Fri, 19 Mar 2021 11:26:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8510864F6D Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine 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.99174.188403 (Exim 4.92) (envelope-from ) id 1lNDGH-0003HC-KG; Fri, 19 Mar 2021 11:25:49 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 99174.188403; Fri, 19 Mar 2021 11:25:49 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lNDGH-0003H5-Gf; Fri, 19 Mar 2021 11:25:49 +0000 Received: by outflank-mailman (input) for mailman id 99174; Fri, 19 Mar 2021 11:25:49 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lNDGH-0003H0-1G for xen-devel@lists.xenproject.org; Fri, 19 Mar 2021 11:25:49 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id ea2e306f-e8d4-4871-9f35-c569a93774a8; Fri, 19 Mar 2021 11:25:48 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 2B553AE05; Fri, 19 Mar 2021 11:25:47 +0000 (UTC) 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" X-Inumbo-ID: ea2e306f-e8d4-4871-9f35-c569a93774a8 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=1616153147; h=from:from:reply-to: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=gX7dBS8PxOqB1DHdSEvhEbIqa4PyVCfh0UAbbhQCg3E=; b=J8Jq+P+ryR8k3dNIDTRk+kbGkTaEFc3Qlv6BFTsgcYp+8DtNBtKdVxQsxKHa5a8AmQMB6e myvdhpvT/DPIKN3WPxBre9zOaojAu0KSXaE048L5P/z9GD1pZWtAwNN5RA4txdF1rN4Nsr FEveI5Zl8v8mGOgSSrgvEJiaXNLEWsI= Subject: Re: [PATCH for-4.15] x86/mem_sharing: copy parent VM's hostp2m's max_mapped_pfn during forking To: Tamas K Lengyel Cc: Tamas K Lengyel , Andrew Cooper , George Dunlap , =?UTF-8?Q?Roger_Pau_Monn=c3=a9?= , Wei Liu , Xen-devel References: <193bfae5-a80a-d02a-377d-c9e11ad038a8@suse.com> From: Jan Beulich Message-ID: <960d2a7a-7be0-58f8-56cc-26d1fa90b7a0@suse.com> Date: Fri, 19 Mar 2021 12:25:46 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 19.03.2021 12:06, Tamas K Lengyel wrote: > On Fri, Mar 19, 2021, 6:23 AM Jan Beulich wrote: > >> On 18.03.2021 22:36, Tamas K Lengyel wrote: >>> --- a/xen/arch/x86/mm/mem_sharing.c >>> +++ b/xen/arch/x86/mm/mem_sharing.c >>> @@ -1761,6 +1761,7 @@ static int copy_settings(struct domain *cd, struct >> domain *d) >>> return rc; >>> >>> copy_tsc(cd, d); >>> + p2m_get_hostp2m(cd)->max_mapped_pfn = >> p2m_get_hostp2m(d)->max_mapped_pfn; >> >> Makes sense to me, yes, but then an immediate question is: What >> about the somewhat similar {min,max}_remapped_gfn fields? Which >> of course implies the more general question of how alternate >> p2m-s (are supposed to) get treated in the first place. From my >> looking at it, fork() doesn't appear to also fork those, but >> also doesn't appear to refuse cloning when altp2m is in use. >> > > It's untested, forking and altp2m is not currently used simultaniously. > Don't know if it should be restricted as not working as I haven't tested > it. Both forking and altp2m is experimental so there be dragons. At some > point I would like to be able to use altp2m in forks but forking a domain > that has altp2m enabled will likely be a setup that's too insane to try to > get working. Well, I see only two (consistent) options - either the other two fields mentioned get copied as well, or altp2m use results in forking getting refused. Jan