On 2021/10/20 0:37, Sven Peter via iommu wrote:
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 | 35 ++++++++++++++++++++++++++++++++--- drivers/iommu/iova.c | 7 ++++--- include/linux/iommu.h | 5 +++++ 3 files changed, 41 insertions(+), 6 deletions(-) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index dd7863e453a5..28896739964b 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -80,6 +80,8 @@ 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, @@ -1974,6 +1976,19 @@ 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 (!iommu_is_paging_domain(domain)) + return 0; + + if (!(domain->pgsize_bitmap & (PAGE_SIZE | (PAGE_SIZE - 1)))) { + pr_warn("IOMMU pages cannot exactly represent CPU pages.\n"); + return -EFAULT; + } + + return 0; +} + static int __iommu_attach_device(struct iommu_domain *domain, struct device *dev) { @@ -1983,9 +1998,23 @@ 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; + }
It looks odd. __iommu_attach_device() attaches an I/O page table for a device. How does it relate to CPU pages? Why is it a failure case if CPU page size is not covered? Best regards, baolu _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
