From patchwork Wed Feb 17 10:46:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jan Beulich X-Patchwork-Id: 12091277 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=-17.2 required=3.0 tests=BAYES_00,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_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 F1372C433DB for ; Wed, 17 Feb 2021 10:46:41 +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 ABC2E64E24 for ; Wed, 17 Feb 2021 10:46:41 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org ABC2E64E24 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.86204.161618 (Exim 4.92) (envelope-from ) id 1lCKLp-0000Is-GX; Wed, 17 Feb 2021 10:46:33 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 86204.161618; Wed, 17 Feb 2021 10:46:33 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1lCKLp-0000Il-DX; Wed, 17 Feb 2021 10:46:33 +0000 Received: by outflank-mailman (input) for mailman id 86204; Wed, 17 Feb 2021 10:46:32 +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 1lCKLn-0000Ie-UB for xen-devel@lists.xenproject.org; Wed, 17 Feb 2021 10:46:31 +0000 Received: from mx2.suse.de (unknown [195.135.220.15]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id 9d84df09-bc85-4edf-a52d-801e5272fe32; Wed, 17 Feb 2021 10:46:31 +0000 (UTC) Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 45E22B1AB; Wed, 17 Feb 2021 10:46:30 +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: 9d84df09-bc85-4edf-a52d-801e5272fe32 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=1613558790; 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=VudHzvHkbrWxXAQT3YkDMWmcJ5pINo+1wlM1FgK45WU=; b=XFf2PzRUoaBtA3RmlfcRvSi0PQbmgi3lL7ZdHaV/xzen1zkf8LJh+ir+L4pcwjyNfisEBj hy+zaBbbBt+ZIxBst9hdcFFbRZgFnxiKYJ5Zu0eBueBlFGNY8jd0j6/+OdRAz++VBMi42u JjRzZKA+e8B4zFzVjp6hcenZyWZ+rkk= Subject: [PATCH 2/3] gnttab: bypass IOMMU (un)mapping when a domain is (un)mapping its own grant From: Jan Beulich To: "xen-devel@lists.xenproject.org" Cc: Andrew Cooper , George Dunlap , Ian Jackson , Julien Grall , Stefano Stabellini , Wei Liu , Rahul Singh References: <156559d5-853a-5bb9-942b-f623627e0907@suse.com> Message-ID: <5bb4fba7-a10b-90c4-82f7-8cde6e8cacfb@suse.com> Date: Wed, 17 Feb 2021 11:46:29 +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: <156559d5-853a-5bb9-942b-f623627e0907@suse.com> Content-Language: en-US Mappings for a domain's own pages should already be present in the IOMMU. While installing the same mapping again is merely redundant (and inefficient), removing the mapping when the grant mapping gets removed is outright wrong in this case: The mapping was there before the map, so should remain in place after unmapping. This affects - Arm Dom0 in the direct mapped case, - x86 PV Dom0 in the "iommu=dom0-strict" / "dom0-iommu=strict" cases, - all x86 PV DomU-s, including driver domains. Reported-by: Rahul Singh Signed-off-by: Jan Beulich Reviewed-by: Julien Grall --- a/xen/common/grant_table.c +++ b/xen/common/grant_table.c @@ -1243,7 +1243,7 @@ map_grant_ref( goto undo_out; } - need_iommu = gnttab_need_iommu_mapping(ld); + need_iommu = ld != rd && gnttab_need_iommu_mapping(ld); if ( need_iommu ) { unsigned int kind; @@ -1493,7 +1493,7 @@ unmap_common( if ( put_handle ) put_maptrack_handle(lgt, op->handle); - if ( rc == GNTST_okay && gnttab_need_iommu_mapping(ld) ) + if ( rc == GNTST_okay && ld != rd && gnttab_need_iommu_mapping(ld) ) { unsigned int kind; int err = 0;