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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no 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 A7FE2C76190 for ; Mon, 22 Jul 2019 15:40:15 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 860F22190F for ; Mon, 22 Jul 2019 15:40:15 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 860F22190F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 59527D81; Mon, 22 Jul 2019 15:40:15 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id C462ECC9; Mon, 22 Jul 2019 15:40:14 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 72BA8224; Mon, 22 Jul 2019 15:40:06 +0000 (UTC) Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E7D003082E72; Mon, 22 Jul 2019 15:40:05 +0000 (UTC) Received: from redhat.com (ovpn-124-54.rdu2.redhat.com [10.10.124.54]) by smtp.corp.redhat.com (Postfix) with SMTP id CA11F60BEC; Mon, 22 Jul 2019 15:39:58 +0000 (UTC) Date: Mon, 22 Jul 2019 11:39:57 -0400 From: "Michael S. Tsirkin" To: Christoph Hellwig Subject: Re: [PATCH 2/2] virtio/virtio_ring: Fix the dma_max_mapping_size call Message-ID: <20190722113403-mutt-send-email-mst@kernel.org> References: <20190722145509.1284-1-eric.auger@redhat.com> <20190722145509.1284-3-eric.auger@redhat.com> <20190722152710.GB3780@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190722152710.GB3780@lst.de> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.46]); Mon, 22 Jul 2019 15:40:06 +0000 (UTC) Cc: jasowang@redhat.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, iommu@lists.linux-foundation.org, eric.auger.pro@gmail.com, robin.murphy@arm.com X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On Mon, Jul 22, 2019 at 05:27:10PM +0200, Christoph Hellwig wrote: > On Mon, Jul 22, 2019 at 04:55:09PM +0200, Eric Auger wrote: > > Do not call dma_max_mapping_size for devices that have no DMA > > mask set, otherwise we can hit a NULL pointer dereference. > > > > This occurs when a virtio-blk-pci device is protected with > > a virtual IOMMU. > > > > Fixes: e6d6dd6c875e ("virtio: Introduce virtio_max_dma_size()") > > Signed-off-by: Eric Auger > > Suggested-by: Christoph Hellwig > > Looks good. virtio maintainers, let me know if you want to queue > it up or if I should pick the patch up through the dma-mapping tree. Personally I dislike this API because I feel presence of dma mask does not strictly have to reflect max size. And generally the requirement to check presence of mask feels like an undocumented hack to me. Even reading code will not help you avoid the warning, everyone will get it wrong and get the warning splat in their logs. So I would prefer just v1 of the patch that makes dma API do the right thing for us. However, if that's not going to be the case, let's fix it up in virtio. In any case, for both v1 and v2 of the patches, you can merge them through your tree: Acked-by: Michael S. Tsirkin -- MST _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu