diff options
Diffstat (limited to 'drivers/iommu/iommufd/hw_pagetable.c')
| -rw-r--r-- | drivers/iommu/iommufd/hw_pagetable.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/iommu/iommufd/hw_pagetable.c b/drivers/iommu/iommufd/hw_pagetable.c index 72a5269984b0..c2b742ffeb0c 100644 --- a/drivers/iommu/iommufd/hw_pagetable.c +++ b/drivers/iommu/iommufd/hw_pagetable.c @@ -42,7 +42,7 @@ void iommufd_hw_pagetable_abort(struct iommufd_object *obj) iommufd_hw_pagetable_destroy(obj); } -int iommufd_hw_pagetable_enforce_cc(struct iommufd_hw_pagetable *hwpt) +static int iommufd_hw_pagetable_enforce_cc(struct iommufd_hw_pagetable *hwpt) { if (hwpt->enforce_cache_coherency) return 0; @@ -116,6 +116,13 @@ iommufd_hw_pagetable_alloc(struct iommufd_ctx *ictx, struct iommufd_ioas *ioas, * doing any maps. It is an iommu driver bug to report * IOMMU_CAP_ENFORCE_CACHE_COHERENCY but fail enforce_cache_coherency on * a new domain. + * + * The cache coherency mode must be configured here and unchanged later. + * Note that a HWPT (non-CC) created for a device (non-CC) can be later + * reused by another device (either non-CC or CC). However, A HWPT (CC) + * created for a device (CC) cannot be reused by another device (non-CC) + * but only devices (CC). Instead user space in this case would need to + * allocate a separate HWPT (non-CC). */ if (idev->enforce_cache_coherency) { rc = iommufd_hw_pagetable_enforce_cc(hwpt); |