iommu: Introduce iommu_iotlb_gather_add_page()

Introduce a helper function for drivers to use when updating an
iommu_iotlb_gather structure in response to an ->unmap() call, rather
than having to open-code the logic in every page-table implementation.

Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index aaf073010a9a485c892c1720bce7b1300c1a122c..ad41aee55bc63ff6d03fb65d8fb1cb6466b1d41e 100644 (file)
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -507,6 +507,31 @@ static inline void iommu_tlb_sync(struct iommu_domain *domain,
        iommu_iotlb_gather_init(iotlb_gather);
 }
 
+static inline void iommu_iotlb_gather_add_page(struct iommu_domain *domain,
+                                              struct iommu_iotlb_gather *gather,
+                                              unsigned long iova, size_t size)
+{
+       unsigned long start = iova, end = start + size;
+
+       /*
+        * If the new page is disjoint from the current range or is mapped at
+        * a different granularity, then sync the TLB so that the gather
+        * structure can be rewritten.
+        */
+       if (gather->pgsize != size ||
+           end < gather->start || start > gather->end) {
+               if (gather->pgsize)
+                       iommu_tlb_sync(domain, gather);
+               gather->pgsize = size;
+       }
+
+       if (gather->end < end)
+               gather->end = end;
+
+       if (gather->start > start)
+               gather->start = start;
+}
+
 /* PCI device grouping function */
 extern struct iommu_group *pci_device_group(struct device *dev);
 /* Generic device grouping function */
@@ -847,6 +872,12 @@ static inline void iommu_iotlb_gather_init(struct iommu_iotlb_gather *gather)
 {
 }
 
+static inline void iommu_iotlb_gather_add_page(struct iommu_domain *domain,
+                                              struct iommu_iotlb_gather *gather,
+                                              unsigned long iova, size_t size)
+{
+}
+
 static inline void iommu_device_unregister(struct iommu_device *iommu)
 {
 }