Re: [PATCH v2 12/13] vfio/type1: use iommu_attach_group() for wrapping PF/VF as mdev

Alex Williamson
2019-09-26T02:37:22Z

On Thu, 5 Sep 2019 15:59:29 +0800
Liu Yi L <yi.l.liu@intel.com> wrote:

> This patch uses iommu_attach_group() to do group attach when it is
> for the case of wrapping a PF/VF as a mdev. iommu_attach_device()
> doesn't support non-singleton iommu group attach. With this change,
> wrapping PF/VF as mdev can work on non-singleton iommu groups.
>
> Cc: Kevin Tian <kevin.tian@intel.com>
> Cc: Lu Baolu <baolu.lu@linux.intel.com>
> Suggested-by: Alex Williamson <alex.williamson@redhat.com>
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> ---
> drivers/vfio/vfio_iommu_type1.c | 22 ++++++++++++++++++----
> 1 file changed, 18 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/vfio/vfio_iommu_type1.c b/drivers/vfio/vfio_iommu_type1.c
> index 054391f..317430d 100644
> --- a/drivers/vfio/vfio_iommu_type1.c
> +++ b/drivers/vfio/vfio_iommu_type1.c
> @@ -1312,13 +1312,20 @@ static int vfio_mdev_attach_domain(struct device *dev, void *data)
> {
> struct iommu_domain *domain = data;
> struct device *iommu_device;
> + struct iommu_group *group;
>
> iommu_device = vfio_mdev_get_iommu_device(dev);
> if (iommu_device) {
> if (iommu_dev_feature_enabled(iommu_device, IOMMU_DEV_FEAT_AUX))
> return iommu_aux_attach_device(domain, iommu_device);
> - else
> - return iommu_attach_device(domain, iommu_device);
> + else {
> + group = iommu_group_get(iommu_device);
> + if (!group) {
> + WARN_ON(1);

What's the value of the WARN_ON here and below?

iommu_group_get() increments the kobject reference, looks like it's
leaked. Thanks,

Alex

> + return -EINVAL;
> + }
> + return iommu_attach_group(domain, group);
> + }
> }
>
> return -EINVAL;
> @@ -1328,13 +1335,20 @@ static int vfio_mdev_detach_domain(struct device *dev, void *data)
> {
> struct iommu_domain *domain = data;
> struct device *iommu_device;
> + struct iommu_group *group;
>
> iommu_device = vfio_mdev_get_iommu_device(dev);
> if (iommu_device) {
> if (iommu_dev_feature_enabled(iommu_device, IOMMU_DEV_FEAT_AUX))
> iommu_aux_detach_device(domain, iommu_device);
> - else
> - iommu_detach_device(domain, iommu_device);
> + else {
> + group = iommu_group_get(iommu_device);
> + if (!group) {
> + WARN_ON(1);
> + return -EINVAL;
> + }
> + iommu_detach_group(domain, group);
> + }
> }
>
> return 0;