Re: [PATCH v3 1/4] iommu: Check IOMMU_DEV_FEAT_AUX feature in aux api's

Alex Williamson
2020-07-29T20:03:54Z

On Tue, 14 Jul 2020 13:57:00 +0800
Lu Baolu <baolu.lu@linux.intel.com> wrote:

> The iommu aux-domain api's work only when IOMMU_DEV_FEAT_AUX is enabled
> for the device. Add this check to avoid misuse.

Shouldn't this really be the IOMMU driver's responsibility to test? If
nothing else, iommu_dev_feature_enabled() needs to get the iommu_ops
from dev->bus->iommu_ops, which is presumably the same iommu_ops we're
then calling from domain->ops to attach/detach the device, so it'd be
more efficient for the IOMMU driver to error on devices that don't
support aux. Thanks,

Alex

> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> ---
> drivers/iommu/iommu.c | 16 +++++++++-------
> 1 file changed, 9 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 1ed1e14a1f0c..e1fdd3531d65 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2725,11 +2725,13 @@ EXPORT_SYMBOL_GPL(iommu_dev_feature_enabled);
> */
> int iommu_aux_attach_device(struct iommu_domain *domain, struct device *dev)
> {
> - int ret = -ENODEV;
> + int ret;
>
> - if (domain->ops->aux_attach_dev)
> - ret = domain->ops->aux_attach_dev(domain, dev);
> + if (!iommu_dev_feature_enabled(dev, IOMMU_DEV_FEAT_AUX) ||
> + !domain->ops->aux_attach_dev)
> + return -ENODEV;
>
> + ret = domain->ops->aux_attach_dev(domain, dev);
> if (!ret)
> trace_attach_device_to_domain(dev);
>
> @@ -2748,12 +2750,12 @@ EXPORT_SYMBOL_GPL(iommu_aux_detach_device);
>
> int iommu_aux_get_pasid(struct iommu_domain *domain, struct device *dev)
> {
> - int ret = -ENODEV;
> + if (!iommu_dev_feature_enabled(dev, IOMMU_DEV_FEAT_AUX) ||
> + !domain->ops->aux_get_pasid)
> + return -ENODEV;
>
> - if (domain->ops->aux_get_pasid)
> - ret = domain->ops->aux_get_pasid(domain, dev);
> + return domain->ops->aux_get_pasid(domain, dev);
>
> - return ret;
> }
> EXPORT_SYMBOL_GPL(iommu_aux_get_pasid);