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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS 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 D4160C433DB for ; Mon, 22 Feb 2021 17:17:27 +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 90AC464DE9 for ; Mon, 22 Feb 2021 17:17:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 90AC464DE9 Authentication-Results: mail.kernel.org; dmarc=pass (p=none dis=none) header.from=xenproject.org 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.88286.165878 (Exim 4.92) (envelope-from ) id 1lEEpf-00043y-3Z; Mon, 22 Feb 2021 17:17:15 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 88286.165878; Mon, 22 Feb 2021 17:17:15 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lEEpf-00043r-0E; Mon, 22 Feb 2021 17:17:15 +0000 Received: by outflank-mailman (input) for mailman id 88286; Mon, 22 Feb 2021 17:17:13 +0000 Received: from mail.xenproject.org ([104.130.215.37]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lEEpd-00043m-9x for xen-devel@lists.xenproject.org; Mon, 22 Feb 2021 17:17:13 +0000 Received: from xenbits.xenproject.org ([104.239.192.120]) by mail.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lEEpd-000500-6L for xen-devel@lists.xenproject.org; Mon, 22 Feb 2021 17:17:13 +0000 Received: from iwj (helo=mariner.uk.xensource.com) by xenbits.xenproject.org with local-bsmtp (Exim 4.92) (envelope-from ) id 1lEEpd-0006ii-5C for xen-devel@lists.xenproject.org; Mon, 22 Feb 2021 17:17:13 +0000 Received: from iwj by mariner.uk.xensource.com with local (Exim 4.89) (envelope-from ) id 1lEEpZ-0001YR-My; Mon, 22 Feb 2021 17:17:09 +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" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=xenproject.org; s=20200302mail; h=References:In-Reply-To:Subject:Cc:To:Date :Message-ID:Content-Transfer-Encoding:Content-Type:MIME-Version:From; bh=A5jwKEr7w9q1MNq9LDQtTavMi2AaamSI7SEYo/eV58w=; b=GQzuoA18pq4LiQHBk3klWJl59y TSL3mImcg6aMKj5B2yRsDdPgAx8MR4b6dEBDbOLzgB6ikpKEfXrU5PI1HSQ0gJMY8Un9C8Sd29ckE T6P8ZWFQfrfaW/Rp/BuugYz3iAhbKDyQw+mySvEl5lizoxDTeSVc/B1haIGf9CMVm4ng=; From: Ian Jackson MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <24627.59157.450971.787744@mariner.uk.xensource.com> Date: Mon, 22 Feb 2021 17:17:09 +0000 To: Jan Beulich Cc: "xen-devel\@lists.xenproject.org" , Andrew Cooper , Wei Liu , Roger Pau =?iso-8859-1?Q?Monn=E9?= , George Dunlap , Kevin Tian , Jun Nakajima , Julien Grall Subject: Re: [PATCH v3 1/2][4.15] VMX: delay p2m insertion of APIC access page In-Reply-To: <04a2869a-282f-783a-6c03-8a2d7209411a@suse.com> References: <4731a3a3-906a-98ac-11ba-6a0723903391@suse.com> <90271e69-c07e-a32c-5531-a79b10ef03dd@suse.com> <24627.38031.77928.536108@mariner.uk.xensource.com> <04a2869a-282f-783a-6c03-8a2d7209411a@suse.com> X-Mailer: VM 8.2.0b under 24.5.1 (i686-pc-linux-gnu) Jan Beulich writes ("Re: [PATCH v3 1/2][4.15] VMX: delay p2m insertion of APIC access page"): > On 22.02.2021 12:25, Ian Jackson wrote: > > Jan Beulich writes ("[PATCH v3 1/2][4.15] VMX: delay p2m insertion of APIC access page"): > >> Inserting the mapping at domain creation time leads to a memory leak > >> when the creation fails later on and the domain uses separate CPU and > >> IOMMU page tables - the latter requires intermediate page tables to be > >> allocated, but there's no freeing of them at present in this case. Since > >> we don't need the p2m insertion to happen this early, avoid the problem > >> altogether by deferring it until the last possible point. > > > > Thanks. > > > >> This comes at > >> the price of not being able to handle an error other than by crashing > >> the domain. > > > > How worried should I be about this ? > > Not overly much I would say. The difference is between a failure > (-ENOMEM) during domain creation vs the domain getting crashed > before it gets first scheduled. This is certainly less friendly > to the user, but lack of memory shouldn't typically happen when > creating domains. Plus the memory talked about here is such that > gets provided explicitly to the domain (the p2m pool), rather > than a system wide pool. OK, thanks. Release-Acked-by: Ian Jackson