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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 7AF57C10F0E for ; Tue, 9 Apr 2019 09:57:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4F07220857 for ; Tue, 9 Apr 2019 09:57:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726133AbfDIJ5u (ORCPT ); Tue, 9 Apr 2019 05:57:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44471 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726035AbfDIJ5u (ORCPT ); Tue, 9 Apr 2019 05:57:50 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 41C0D307CDE3; Tue, 9 Apr 2019 09:57:50 +0000 (UTC) Received: from gondolin (ovpn-117-119.ams2.redhat.com [10.36.117.119]) by smtp.corp.redhat.com (Postfix) with ESMTP id 25ABC5D719; Tue, 9 Apr 2019 09:57:46 +0000 (UTC) Date: Tue, 9 Apr 2019 11:57:43 +0200 From: Cornelia Huck To: Halil Pasic Cc: kvm@vger.kernel.org, linux-s390@vger.kernel.org, Martin Schwidefsky , Sebastian Ott , virtualization@lists.linux-foundation.org, Christian Borntraeger , Viktor Mihajlovski , Vasily Gorbik , Janosch Frank , Claudio Imbrenda , Farhan Ali , Eric Farman Subject: Re: [RFC PATCH 02/12] virtio/s390: DMA support for virtio-ccw Message-ID: <20190409115743.26e51b81.cohuck@redhat.com> In-Reply-To: <20190404231622.52531-3-pasic@linux.ibm.com> References: <20190404231622.52531-1-pasic@linux.ibm.com> <20190404231622.52531-3-pasic@linux.ibm.com> Organization: Red Hat GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.49]); Tue, 09 Apr 2019 09:57:50 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Fri, 5 Apr 2019 01:16:12 +0200 Halil Pasic wrote: > Currently we have a problem if a virtio-ccw device has > VIRTIO_F_IOMMU_PLATFORM. Can you please describe what the actual problem is? > In future we do want to support DMA API with > virtio-ccw. > > Let us do the plumbing, so the feature VIRTIO_F_IOMMU_PLATFORM works > with virtio-ccw. > > Let us also switch from legacy avail/used accessors to the DMA aware > ones (even if it isn't strictly necessary). I think with this change we can remove the legacy accessors, if I didn't mis-grep. > > Signed-off-by: Halil Pasic > --- > drivers/s390/virtio/virtio_ccw.c | 23 +++++++++++++++++------ > 1 file changed, 17 insertions(+), 6 deletions(-) > > diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c > index edf4afe2d688..5956c9e820bb 100644 > --- a/drivers/s390/virtio/virtio_ccw.c > +++ b/drivers/s390/virtio/virtio_ccw.c > @@ -66,6 +66,7 @@ struct virtio_ccw_device { > bool device_lost; > unsigned int config_ready; > void *airq_info; > + __u64 dma_mask; u64? > }; > > struct vq_info_block_legacy { > @@ -536,8 +537,8 @@ static struct virtqueue *virtio_ccw_setup_vq(struct virtio_device *vdev, > info->info_block->s.desc = queue; > info->info_block->s.index = i; > info->info_block->s.num = info->num; > - info->info_block->s.avail = (__u64)virtqueue_get_avail(vq); > - info->info_block->s.used = (__u64)virtqueue_get_used(vq); > + info->info_block->s.avail = (__u64)virtqueue_get_avail_addr(vq); > + info->info_block->s.used = (__u64)virtqueue_get_used_addr(vq); > ccw->count = sizeof(info->info_block->s); > } > ccw->cmd_code = CCW_CMD_SET_VQ; > @@ -769,10 +770,8 @@ static u64 virtio_ccw_get_features(struct virtio_device *vdev) > static void ccw_transport_features(struct virtio_device *vdev) > { > /* > - * Packed ring isn't enabled on virtio_ccw for now, > - * because virtio_ccw uses some legacy accessors, > - * e.g. virtqueue_get_avail() and virtqueue_get_used() > - * which aren't available in packed ring currently. > + * There shouldn't be anything that precludes supporting paced. s/paced/packed/ > + * TODO: Remove the limitation after having another look into this. > */ > __virtio_clear_bit(vdev, VIRTIO_F_RING_PACKED); > } > @@ -1255,6 +1254,18 @@ static int virtio_ccw_online(struct ccw_device *cdev) > ret = -ENOMEM; > goto out_free; > } > + vcdev->vdev.dev.parent = &cdev->dev; That one makes sense, pci and mmio are doing that as well. > + cdev->dev.dma_mask = &vcdev->dma_mask; That one feels a bit weird. Will this change in one of the follow-on patches? (Have not yet looked at the whole series.) > + > + ret = dma_set_mask_and_coherent(&cdev->dev, DMA_BIT_MASK(64)); > + if (ret) > + ret = dma_set_mask_and_coherent(&cdev->dev, > + DMA_BIT_MASK(32)); > + if (ret) { > + dev_warn(&cdev->dev, "Failed to enable 64-bit or 32-bit DMA. Trying to continue, but this might not work.\n"); This does not look like you'd try to continue? > + goto out_free; > + } > + > vcdev->config_block = kzalloc(sizeof(*vcdev->config_block), > GFP_DMA | GFP_KERNEL); > if (!vcdev->config_block) {