The iova allocator is capable of handling any granularity which is a power of two. Remove the much stronger condition that the granularity must be smaller or equal to the CPU page size from a BUG_ON there. Instead, check this condition during __iommu_attach_device and fail gracefully.
Signed-off-by: Sven Peter <s...@svenpeter.dev> --- drivers/iommu/iommu.c | 34 +++++++++++++++++++++++++++++++--- drivers/iommu/iova.c | 7 ++++--- 2 files changed, 35 insertions(+), 6 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 1de503ddb343..5854a4ef5681 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -78,6 +78,8 @@ static struct iommu_domain *__iommu_domain_alloc(struct bus_type *bus, unsigned type); static int __iommu_attach_device(struct iommu_domain *domain, struct device *dev); +static void __iommu_detach_device(struct iommu_domain *domain, + struct device *dev); static int __iommu_attach_group(struct iommu_domain *domain, struct iommu_group *group); static void __iommu_detach_group(struct iommu_domain *domain, @@ -1964,6 +1966,18 @@ void iommu_domain_free(struct iommu_domain *domain) } EXPORT_SYMBOL_GPL(iommu_domain_free); +static int iommu_check_page_size(struct iommu_domain *domain) +{ + if (!(domain->type & __IOMMU_DOMAIN_PAGING)) + return 0; + + if ((1 << __ffs(domain->pgsize_bitmap)) > PAGE_SIZE) { + pr_warn("IOMMU page size cannot represent CPU pages.\n"); + return -EFAULT; + } + + return 0; +} static int __iommu_attach_device(struct iommu_domain *domain, struct device *dev) { @@ -1973,9 +1987,23 @@ static int __iommu_attach_device(struct iommu_domain *domain, return -ENODEV; ret = domain->ops->attach_dev(domain, dev); - if (!ret) - trace_attach_device_to_domain(dev); - return ret; + if (ret) + return ret; + + /* + * Check that CPU pages can be represented by the IOVA granularity. + * This has to be done after ops->attach_dev since many IOMMU drivers + * only limit domain->pgsize_bitmap after having attached the first + * device. + */ + ret = iommu_check_page_size(domain); + if (ret) { + __iommu_detach_device(domain, dev); + return ret; + } + + trace_attach_device_to_domain(dev); + return 0; } int iommu_attach_device(struct iommu_domain *domain, struct device *dev) diff --git a/drivers/iommu/iova.c b/drivers/iommu/iova.c index b6cf5f16123b..e0f8adde0f1b 100644 --- a/drivers/iommu/iova.c +++ b/drivers/iommu/iova.c @@ -50,10 +50,11 @@ init_iova_domain(struct iova_domain *iovad, unsigned long granule, { /* * IOVA granularity will normally be equal to the smallest - * supported IOMMU page size; both *must* be capable of - * representing individual CPU pages exactly. + * supported IOMMU page size; while both usually are capable of + * representing individual CPU pages exactly the IOVA allocator + * supports any granularities that are an exact power of two. */ - BUG_ON((granule > PAGE_SIZE) || !is_power_of_2(granule)); + BUG_ON(!is_power_of_2(granule)); spin_lock_init(&iovad->iova_rbtree_lock); iovad->rbroot = RB_ROOT; -- 2.25.1 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu