Re: [PATCH] vfio: platform: use vfio_iommu_group_get/put

Eric Auger
2016-05-20T07:58:32Z

Hi,
On 05/19/2016 11:01 PM, Alex Williamson wrote:
> On Tue, 10 May 2016 15:40:28 +0800
> Peng Fan <van.freenix@gmail.com> 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 <van.freenix@gmail.com> 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.

Best Regards

Eric
>
> Alex
>
>>>>
>>>> Signed-off-by: Peng Fan <van.freenix@gmail.com>
>>>> Cc: Baptiste Reynal <b.reynal@virtualopensystems.com>
>>>> Cc: Alex Williamson <alex.williamson@redhat.com>
>>>> ---
>>>> 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;
>>>
>