From: Nicolin Chen nicolinc@nvidia.com Sent: Saturday, May 20, 2023 3:09 AM
On Fri, May 19, 2023 at 09:06:20AM +0000, Tian, Kevin wrote:
@@ -73,14 +77,22 @@ int iommufd_hw_pagetable_enforce_cc(struct iommufd_hw_pagetable *hwpt) */ struct iommufd_hw_pagetable * iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas,
struct iommufd_device *idev, boolimmediate_attach)
struct iommufd_device *idev,struct iommufd_hw_pagetable *parent,union iommu_domain_user_data *user_data,bool immediate_attach){ const struct iommu_ops *ops = dev_iommu_ops(idev->dev);
struct iommu_domain *parent_domain = NULL; struct iommufd_hw_pagetable *hwpt;bool type_unmanaged, type_nested; int rc; lockdep_assert_held(&ioas->mutex);if ((user_data || parent) && !ops->domain_alloc_user)return ERR_PTR(-EOPNOTSUPP);Do we allow specifying parent w/o user_data?
I don't think so. Perhaps we should do a double check:
- if (!!user_data ^ !!parent)
return ERR_PTR(-EINVAL);
I think we allow creating a s2 hwpt with user_data so it should be:
if (parent && !user_data) return ERR_PTR(-INVAL);
@@ -99,6 +117,15 @@ iommufd_hw_pagetable_alloc(struct
iommufd_ctx
*ictx, struct iommufd_ioas *ioas, goto out_abort; }
/* It must be either NESTED or UNMANAGED, depending onparent_domain */
type_nested = hwpt->domain->type == IOMMU_DOMAIN_NESTED;type_unmanaged = hwpt->domain->type ==IOMMU_DOMAIN_UNMANAGED;
no need of one-time used variables. Just put the conditions directly in WARN_ON.
It is to improve the readability. Otherwise, we'd have:
if (WARN_ON((parent_domain && hwpt->domain->type != IOMMU_DOMAIN_NESTED) || (!parent_domain && hwpt->domain->type != IOMMU_DOMAIN_UNMANAGED)))
IMHO this is already very clear w/o defining additional variables. 😊