On Thu, Aug 22, 2024 at 11:45:55AM -0300, Jason Gunthorpe wrote:
These three implementations of map_pages() all succeed if a mapping is requested with no read or write. Since they return back to __iommu_map() leaving the mapped output as 0 it triggers an infinite loop. Therefore nothing is using no-access protection bits.
Further, VFIO and iommufd rely on iommu_iova_to_phys() to get back PFNs stored by map, if iommu_map() succeeds but iommu_iova_to_phys() fails that will create serious bugs.
Thus remove this never used "nothing to do" concept and just fail map immediately.
Fixes: e5fc9753b1a8 ("iommu/io-pgtable: Add ARMv7 short descriptor support") Fixes: e1d3c0fd701d ("iommu: add ARM LPAE page table allocator") Fixes: 745ef1092bcf ("iommu/io-pgtable: Move Apple DART support to its own file") Signed-off-by: Jason Gunthorpe jgg@nvidia.com
drivers/iommu/io-pgtable-arm-v7s.c | 3 +-- drivers/iommu/io-pgtable-arm.c | 3 +-- drivers/iommu/io-pgtable-dart.c | 3 +-- 3 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/drivers/iommu/io-pgtable-arm-v7s.c b/drivers/iommu/io-pgtable-arm-v7s.c index 75f244a3e12df6..06ffc683b28fee 100644 --- a/drivers/iommu/io-pgtable-arm-v7s.c +++ b/drivers/iommu/io-pgtable-arm-v7s.c @@ -552,9 +552,8 @@ static int arm_v7s_map_pages(struct io_pgtable_ops *ops, unsigned long iova, paddr >= (1ULL << data->iop.cfg.oas))) return -ERANGE;
- /* If no access, then nothing to do */ if (!(prot & (IOMMU_READ | IOMMU_WRITE)))
return 0;
return -EINVAL;while (pgcount--) { ret = __arm_v7s_map(data, iova, paddr, pgsize, prot, 1, data->pgd, diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c index f5d9fd1f45bf49..ff4149ae1751d4 100644 --- a/drivers/iommu/io-pgtable-arm.c +++ b/drivers/iommu/io-pgtable-arm.c @@ -515,9 +515,8 @@ static int arm_lpae_map_pages(struct io_pgtable_ops *ops, unsigned long iova, if (WARN_ON(iaext || paddr >> cfg->oas)) return -ERANGE;
- /* If no access, then nothing to do */ if (!(iommu_prot & (IOMMU_READ | IOMMU_WRITE)))
return 0;
return -EINVAL;
I think just removing this hunk altogether would get us the right semantics for stage-2 mappings, but it's esoteric and not used so -EINVAL is probably better:
Acked-by: Will Deacon will@kernel.org
Will