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 1B6C3C433DB for ; Wed, 17 Feb 2021 14:54:43 +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 A97F164E02 for ; Wed, 17 Feb 2021 14:54:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A97F164E02 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.86303.161931 (Exim 4.92) (envelope-from ) id 1lCODh-0000Cy-Kp; Wed, 17 Feb 2021 14:54:25 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 86303.161931; Wed, 17 Feb 2021 14:54:25 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lCODh-0000Cr-Gr; Wed, 17 Feb 2021 14:54:25 +0000 Received: by outflank-mailman (input) for mailman id 86303; Wed, 17 Feb 2021 14:54:23 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lCODf-0000Cj-SP for xen-devel@lists.xenproject.org; Wed, 17 Feb 2021 14:54:23 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id e1914e24-ecf2-4c54-9d08-0b923d4dc645; Wed, 17 Feb 2021 14:54:23 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 421DBB8FA; Wed, 17 Feb 2021 14:54:22 +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: e1914e24-ecf2-4c54-9d08-0b923d4dc645 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=1613573662; 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=yF/cluvsiJCFqkm34Ubp610JZTcmodW0JUMP+pXIss8=; b=GCaOQtiLlIF7lQuBb8zh9KNKgIFxZOxRHwnAoJtipEtFqjHs96GoZ72ccI+IC0uNQG7Y2t q4OJqDNKwmm/AvmC9JRrk8rGDeJyoeICNdb/0kCPromd1+glij/3k7IxJYzzGktRU8jgvb boeyf3hoDdYfLmf/JCYF62bWb68j83o= Subject: Re: [for-4.15][PATCH v3 1/3] xen/iommu: x86: Clear the root page-table before freeing the page-tables To: Julien Grall Cc: hongyxia@amazon.co.uk, iwj@xenproject.org, Julien Grall , Andrew Cooper , Kevin Tian , Paul Durrant , xen-devel@lists.xenproject.org References: <20210217142458.3769-1-julien@xen.org> <20210217142458.3769-2-julien@xen.org> From: Jan Beulich Message-ID: Date: Wed, 17 Feb 2021 15:54:21 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <20210217142458.3769-2-julien@xen.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit On 17.02.2021 15:24, Julien Grall wrote: > --- a/xen/drivers/passthrough/amd/pci_amd_iommu.c > +++ b/xen/drivers/passthrough/amd/pci_amd_iommu.c > @@ -381,9 +381,18 @@ static int amd_iommu_assign_device(struct domain *d, u8 devfn, > return reassign_device(pdev->domain, d, devfn, pdev); > } > > +static void iommu_clear_root_pgtable(struct domain *d) Nit: amd_iommu_ as a prefix would be okay here considering other (static) functions also use it. Since it is a static function, no prefix at all would also do (my personal preference). But iommu_ as a prefix isn't helpful and results in needless re-use of VT-d's name. > --- a/xen/drivers/passthrough/x86/iommu.c > +++ b/xen/drivers/passthrough/x86/iommu.c > @@ -267,6 +267,15 @@ int iommu_free_pgtables(struct domain *d) > struct page_info *pg; > unsigned int done = 0; > > + if ( !is_iommu_enabled(d) ) > + return 0; > + > + /* > + * Pages will be moved to the free list below. So we want to > + * clear the root page-table to avoid any potential use after-free. > + */ > + hd->platform_ops->clear_root_pgtable(d); Taking amd_iommu_alloc_root() as example, is this really correct prior to what is now patch 2? What guarantees a new root table won't get allocated subsequently? Jan