From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755840AbcETQVb (ORCPT ); Fri, 20 May 2016 12:21:31 -0400 Received: from mail-wm0-f46.google.com ([74.125.82.46]:37791 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755737AbcETQV1 (ORCPT ); Fri, 20 May 2016 12:21:27 -0400 Subject: Re: [PATCH] vfio: platform: use vfio_iommu_group_get/put To: Peng Fan References: <1462788103-19906-1-git-send-email-van.freenix@gmail.com> <20160509093238.3901f0b7@t450s.home> <20160510074025.GA1064@linux-7smt.suse> <20160519150149.7a8b80ba@ul30vt.home> <573EC3A8.4050008@linaro.org> <20160520083627.GA23014@linux-7smt.suse> <573ED745.1040900@linaro.org> <20160520095658.GD23014@linux-7smt.suse> Cc: Baptiste Reynal , Alex Williamson , "open list:VFIO DRIVER" , open list From: Eric Auger Message-ID: <573F392E.3010108@linaro.org> Date: Fri, 20 May 2016 18:19:58 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <20160520095658.GD23014@linux-7smt.suse> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peng, On 05/20/2016 11:56 AM, Peng Fan wrote: > Hi Eric, > > On Fri, May 20, 2016 at 11:22:13AM +0200, Eric Auger wrote: >> Hi Peng, >> On 05/20/2016 10:36 AM, Peng Fan wrote: >>> Hi, >>> >>> On Fri, May 20, 2016 at 10:20:32AM +0200, Baptiste Reynal wrote: >>>> Hi, >>>> >>>> On Fri, May 20, 2016 at 9:58 AM, Eric Auger wrote: >>>>> >>>>> Hi, >>>>> On 05/19/2016 11:01 PM, Alex Williamson wrote: >>>>>> On Tue, 10 May 2016 15:40:28 +0800 >>>>>> Peng Fan wrote: >>>>>> >>>>>>> Hi Alex, >>>>>>> >>>>>>> On Mon, May 09, 2016 at 09:32:38AM -0600, Alex Williamson wrote: >>>>>>>> On Mon, 9 May 2016 18:01:43 +0800 >>>>>>>> Peng Fan wrote: >>>>>>>> >>>>>>>>> Use vfio_iommu_group_get and vfio_iommu_group_put, but not >>>>>>>>> iommu_group_get or iommu_group_put. >>>>>>>> >>>>>>>> I assume you're trying to duplicate the vfio_pci changes from commit >>>>>>>> 03a76b60f8ba to enable no-iommu mode. That would be really relevant >>>>>>>> information for the commit log. >>>>>>> >>>>>>> This is not to support non-iommu for vfio platform. I just think >>>>>>> vfio_iommu_group_get/put is vfio core API and should be used by >>>>>>> vfio-pci and vfio-platform. >>>>>> >>>>>> Hi Peng, >>>>>> >>>>>> I suppose I would consider this an optional part of the internal vfio >>>>>> API, it's only real purpose it to provide the ability to create fake >>>>>> groups which are only used for no-iommu. It's perfectly legitimate to >>>>>> use iommu_group_get/put if there is no desire to enable no-iommu. >>>>>> Baptiste, Eric, do you have an opinion whether enabling no-iommu in >>>>>> vfio/platform is something we should do? Thanks, >>>>> I think it would make sense to introduce that no-iommu feature for >>>>> vfio-platform because it allows potential users to get familiar with >>>>> VFIO platform without having the proper HW. I also thought the primary >>>>> purpose of this patch was to introduce that support. >>> >>> Yeah. Initially I would like to try vfio on my i.MX6/7 boards which does not >>> have HW iommu. I am new to this, so just wrote this simple patch when I was >>> reading the source code. >>> >>>> >>>> Since safety issues have already been addressed for the PCI patch >>>> series, I don't see any reason not to enable it. You might extend the >>>> commit message to remind those issues. >>> >>> Eric, Baptiste, >>> >>> Is vfio-platform no-iommu on your TODO list? I am happy to help test. >>> If not, I can try work on this if you could guide me -:) >> No it is not at the moment. shouldn't it work already with this very >> patch? I will be happy to bring support to you if needed. > > This patch was code inspection work. Since it did not break vfio-platform > iommu, I sent it out. I have not played well with userspace test > code/step or qemu (: > > Is it ok for me to test vfio-platform no-iommu using a platform device > withou DMA capability, such as simple UART? My feeling is that it is a reasonable start. Best Regards Eric > > If it's ok, I'll follow the test code[1] to write my test code and do some test. > > Regards, > Peng. > > [1] https://github.com/virtualopensystems/vfio-host-test/tree/master/src_test > >> >> Best Regards >> >> Eric >>> >>> Thanks, >>> Peng. >>>> >>>> Best regards, >>>> Baptiste >>>> >>>>> >>>>> Best Regards >>>>> >>>>> Eric >>>>>> >>>>>> Alex >>>>>> >>>>>>>>> >>>>>>>>> Signed-off-by: Peng Fan >>>>>>>>> Cc: Baptiste Reynal >>>>>>>>> Cc: Alex Williamson >>>>>>>>> --- >>>>>>>>> drivers/vfio/platform/vfio_platform_common.c | 6 +++--- >>>>>>>>> 1 file changed, 3 insertions(+), 3 deletions(-) >>>>>>>>> >>>>>>>>> diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c >>>>>>>>> index e65b142..582885e 100644 >>>>>>>>> --- a/drivers/vfio/platform/vfio_platform_common.c >>>>>>>>> +++ b/drivers/vfio/platform/vfio_platform_common.c >>>>>>>>> @@ -561,7 +561,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev, >>>>>>>>> >>>>>>>>> vdev->device = dev; >>>>>>>>> >>>>>>>>> - group = iommu_group_get(dev); >>>>>>>>> + group = vfio_iommu_group_get(dev); >>>>>>>>> if (!group) { >>>>>>>>> pr_err("VFIO: No IOMMU group for device %s\n", vdev->name); >>>>>>>>> return -EINVAL; >>>>>>>>> @@ -569,7 +569,7 @@ int vfio_platform_probe_common(struct vfio_platform_device *vdev, >>>>>>>>> >>>>>>>>> ret = vfio_add_group_dev(dev, &vfio_platform_ops, vdev); >>>>>>>>> if (ret) { >>>>>>>>> - iommu_group_put(group); >>>>>>>>> + vfio_iommu_group_put(group); >>>>>>>>> return ret; >>>>>>>>> } >>>>>>>>> >>>>>>>>> @@ -589,7 +589,7 @@ struct vfio_platform_device *vfio_platform_remove_common(struct device *dev) >>>>>>>>> >>>>>>>>> if (vdev) { >>>>>>>>> vfio_platform_put_reset(vdev); >>>>>>>>> - iommu_group_put(dev->iommu_group); >>>>>>>>> + vfio_iommu_group_put(dev->iommu_group, dev); >>>>>>>>> } >>>>>>>>> >>>>>>>>> return vdev; >>>>>>>> >>>>>> >>>>> >>