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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 924CAC10F0E for ; Tue, 9 Apr 2019 15:48:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 666202084C for ; Tue, 9 Apr 2019 15:48:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726559AbfDIPsI (ORCPT ); Tue, 9 Apr 2019 11:48:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:35234 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726396AbfDIPsI (ORCPT ); Tue, 9 Apr 2019 11:48:08 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 370E17D0F2; Tue, 9 Apr 2019 15:48:08 +0000 (UTC) Received: from gondolin (ovpn-117-119.ams2.redhat.com [10.36.117.119]) by smtp.corp.redhat.com (Postfix) with ESMTP id CCB6F600D4; Tue, 9 Apr 2019 15:48:03 +0000 (UTC) Date: Tue, 9 Apr 2019 17:47:55 +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: <20190409174755.5f62d04e.cohuck@redhat.com> In-Reply-To: <20190409152313.0296e8f1@oc2783563651> References: <20190404231622.52531-1-pasic@linux.ibm.com> <20190404231622.52531-3-pasic@linux.ibm.com> <20190409115743.26e51b81.cohuck@redhat.com> <20190409132927.5df3bc50@oc2783563651> <20190409150120.61abad60.cohuck@redhat.com> <20190409152313.0296e8f1@oc2783563651> 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 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Tue, 09 Apr 2019 15:48:08 +0000 (UTC) Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, 9 Apr 2019 15:23:13 +0200 Halil Pasic wrote: > On Tue, 9 Apr 2019 15:01:20 +0200 > Cornelia Huck wrote: > > > On Tue, 9 Apr 2019 13:29:27 +0200 > > Halil Pasic wrote: > > > > > On Tue, 9 Apr 2019 11:57:43 +0200 > > > Cornelia Huck wrote: > > > > > > > On Fri, 5 Apr 2019 01:16:12 +0200 > > > > Halil Pasic wrote: > > > > > @@ -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.) > > > > > > I don't thinks so. Do you mean this should happen within the cio code? > > > I think I started out with the idea to keep the scope as narrow as > > > possible. Do you have any suggestions? > > > > From what I see, you set the mask from the virtio-ccw side, then > > propagate it up to the general ccw_device, and then the generic virtio > > code will fetch it from the ccw_device. > > Right! For some reason dma_mask is a pointer. And I need virtio core to > use a sane value for virtio_ccw devices. > > > Don't you potentially need > > something for other ccw_devices in that protected hipervisor case as > > well (e.g for 3270)? > > > Maybe, maybe not. The first stage is likely to be virito only. I would > prefer sorting out stuff like 3270 as the need arises. Also see my > response to patch 4 (Message-Id: <20190409141114.7dcce94a@oc2783563651>). As long as the infrastructure is flexible enough to be extended later, ok. I still need to read that mail. > > > > > > > > > > > > > > > + > > > > > + 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? > > > > > > > > > > I remember now. First I did continue, then I changed this to fail > > > hard so I can not ignore any such problems while smoke testing ('I > > > don't always check the kernel messages'), but kept the old message. > > > This basically should not fail anyway, otherwise we have a problem > > > AFAIU. > > > > > > By the way virtio-pci tries to continue indeed, and this is also > > > where the wording comes from ;). > > > > > > What would you prefer? Try to continue or fail right away? > > > > If it does not have a chance of working properly in the general case, > > I'd fail. > > > > Agreed! I will make it so. Would dropping ' Trying to continue, but > this might not work.' from the warning message work for you? Sounds fine. > > I could also drop the attempt to set a 32 bit mask if you agree. Do you? Only if you also drop it from the message as well ;) Not sure in what cases you'll fail to set a 64 bit mask, but succeed with a 32 bit mask. If there's no sensible situation where that might happen, I'd just go ahead and drop it.