From patchwork Tue Jan 29 08:43:41 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Joerg Roedel X-Patchwork-Id: 10785807 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 167F2184E for ; Tue, 29 Jan 2019 08:45:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 088EC29EE6 for ; Tue, 29 Jan 2019 08:45:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id F07312A677; Tue, 29 Jan 2019 08:45:19 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 9642229EE6 for ; Tue, 29 Jan 2019 08:45:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726371AbfA2IoN (ORCPT ); Tue, 29 Jan 2019 03:44:13 -0500 Received: from 8bytes.org ([81.169.241.247]:35592 "EHLO theia.8bytes.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727233AbfA2Inq (ORCPT ); Tue, 29 Jan 2019 03:43:46 -0500 Received: by theia.8bytes.org (Postfix, from userid 1000) id CBAED493; Tue, 29 Jan 2019 09:43:44 +0100 (CET) From: Joerg Roedel To: "Michael S . Tsirkin" , Jason Wang , Konrad Rzeszutek Wilk , Christoph Hellwig Cc: Jens Axboe , virtualization@lists.linux-foundation.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, jfehlig@suse.com, jon.grimm@amd.com, brijesh.singh@amd.com, joro@8bytes.org, jroedel@suse.de Subject: [PATCH 4/5] virtio: Introduce virtio_max_dma_size() Date: Tue, 29 Jan 2019 09:43:41 +0100 Message-Id: <20190129084342.26030-5-joro@8bytes.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190129084342.26030-1-joro@8bytes.org> References: <20190129084342.26030-1-joro@8bytes.org> Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Joerg Roedel This function returns the maximum segment size for a single dma transaction of a virtio device. The possible limit comes from the SWIOTLB implementation in the Linux kernel, that has an upper limit of (currently) 256kb of contiguous memory it can map. Other DMA-API implementations might also have limits. Use the new dma_max_mapping_size() function to determine the maximum mapping size when DMA-API is in use for virtio. Reviewed-by: Konrad Rzeszutek Wilk Signed-off-by: Joerg Roedel Reviewed-by: Christoph Hellwig --- drivers/virtio/virtio_ring.c | 10 ++++++++++ include/linux/virtio.h | 2 ++ 2 files changed, 12 insertions(+) diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index cd7e755484e3..9ca3fe6af9fa 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -266,6 +266,16 @@ static bool vring_use_dma_api(struct virtio_device *vdev) return false; } +size_t virtio_max_dma_size(struct virtio_device *vdev) +{ + size_t max_segment_size = SIZE_MAX; + + if (vring_use_dma_api(vdev)) + max_segment_size = dma_max_mapping_size(&vdev->dev); + + return max_segment_size; +} + static void *vring_alloc_queue(struct virtio_device *vdev, size_t size, dma_addr_t *dma_handle, gfp_t flag) { diff --git a/include/linux/virtio.h b/include/linux/virtio.h index fa1b5da2804e..673fe3ef3607 100644 --- a/include/linux/virtio.h +++ b/include/linux/virtio.h @@ -157,6 +157,8 @@ int virtio_device_freeze(struct virtio_device *dev); int virtio_device_restore(struct virtio_device *dev); #endif +size_t virtio_max_dma_size(struct virtio_device *vdev); + #define virtio_device_for_each_vq(vdev, vq) \ list_for_each_entry(vq, &vdev->vqs, list)