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, INCLUDES_PATCH,MAILING_LIST_MULTI,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 23E71C76186 for ; Wed, 24 Jul 2019 22:11:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E8F5D21880 for ; Wed, 24 Jul 2019 22:11:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728838AbfGXWLB (ORCPT ); Wed, 24 Jul 2019 18:11:01 -0400 Received: from mail-qt1-f196.google.com ([209.85.160.196]:38348 "EHLO mail-qt1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727366AbfGXWLA (ORCPT ); Wed, 24 Jul 2019 18:11:00 -0400 Received: by mail-qt1-f196.google.com with SMTP id n11so47120788qtl.5 for ; Wed, 24 Jul 2019 15:10:59 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=ZiT1oQ3le6gupTI0pwbmKNqZ9qeZj4CLKlZRplQnTAY=; b=LSAuPTNTddZAq11CV6juSDpR+59sYlFeW9uiUcpiYSFyxyth1tsl3zPWGvkh7hC78P 4J8LZyQ14qxuNhhwNI8bPqBDk/XlAb+UAy9YXbeaXj5zE+YhatLmv/zpgl+Dtu+rgxCz GZTzYMseQpVM38RZDdQW4BJprQIIxEJfUnp8gDek9FS6GkFkR9Lt2eA5WYHJBeU4kj9z lVcvj9BslU1VTHSK+nRmHzjZdMhkvEabplYCbb/bnrl9ykzJj8k+Qp9z1Ru/mITExptz bsrsHIt/qxU4o1Rv3OPo48M9ylb4vtcuRBoCleYwqTCZF3reQjCFWoENI3abeS8s8wlN 3KQw== X-Gm-Message-State: APjAAAXsmkO34PyjaYq0PGtUMd4pfpY3aKBc6VIUmZ9vIg9GrUEA1FuU nKPNLXVfG/XzpV0DSXL9ILSqew== X-Google-Smtp-Source: APXvYqwsl34mAeI1ycJq/WD6DI4M1e7pIzRNfVQKDNOWFybfH6EBHoRGki9/ggsy5dsu/ZaP8T89Pw== X-Received: by 2002:ac8:3014:: with SMTP id f20mr59384146qte.69.1564006259498; Wed, 24 Jul 2019 15:10:59 -0700 (PDT) Received: from redhat.com (bzq-79-181-91-42.red.bezeqint.net. [79.181.91.42]) by smtp.gmail.com with ESMTPSA id g54sm28199760qtc.61.2019.07.24.15.10.56 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 24 Jul 2019 15:10:58 -0700 (PDT) Date: Wed, 24 Jul 2019 18:10:53 -0400 From: "Michael S. Tsirkin" To: Christoph Hellwig Cc: Robin Murphy , Eric Auger , eric.auger.pro@gmail.com, m.szyprowski@samsung.com, jasowang@redhat.com, virtualization@lists.linux-foundation.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/2] virtio/virtio_ring: Fix the dma_max_mapping_size call Message-ID: <20190723114750-mutt-send-email-mst@kernel.org> References: <20190722145509.1284-1-eric.auger@redhat.com> <20190722145509.1284-3-eric.auger@redhat.com> <20190723153851.GE720@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190723153851.GE720@lst.de> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 23, 2019 at 05:38:51PM +0200, Christoph Hellwig wrote: > On Mon, Jul 22, 2019 at 04:36:09PM +0100, Robin Murphy wrote: > >> diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > >> index c8be1c4f5b55..37c143971211 100644 > >> --- a/drivers/virtio/virtio_ring.c > >> +++ b/drivers/virtio/virtio_ring.c > >> @@ -262,7 +262,7 @@ size_t virtio_max_dma_size(struct virtio_device *vdev) > >> { > >> size_t max_segment_size = SIZE_MAX; > >> - if (vring_use_dma_api(vdev)) > >> + if (vring_use_dma_api(vdev) && vdev->dev.dma_mask) > > > > Hmm, might it make sense to roll that check up into vring_use_dma_api() > > itself? After all, if the device has no mask then it's likely that other > > DMA API ops wouldn't really work as expected either. > > Makes sense to me. Christoph - would a documented API wrapping dma_mask make sense? With the documentation explaining how users must desist from using DMA APIs if that returns false ... -- MST