iommu: Introduce struct iommu_iotlb_gather for batching TLB flushes

To permit batching of TLB flushes across multiple calls to the IOMMU
driver's ->unmap() implementation, introduce a new structure for
tracking the address range to be flushed and the granularity at which
the flushing is required.

This is hooked into the IOMMU API and its caller are updated to make use
of the new structure. Subsequent patches will plumb this into the IOMMU
drivers as well, but for now the gathering information is ignored.

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

1 files changed, 39 insertions, 4 deletions

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 1e21431262d9..aaf073010a9a 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -192,6 +192,23 @@ struct iommu_sva_ops {
 #ifdef CONFIG_IOMMU_API
 
 /**
+ * struct iommu_iotlb_gather - Range information for a pending IOTLB flush
+ *
+ * @start: IOVA representing the start of the range to be flushed
+ * @end: IOVA representing the end of the range to be flushed (exclusive)
+ * @pgsize: The interval at which to perform the flush
+ *
+ * This structure is intended to be updated by multiple calls to the
+ * ->unmap() function in struct iommu_ops before eventually being passed
+ * into ->iotlb_sync().
+ */
+struct iommu_iotlb_gather {
+	unsigned long		start;
+	unsigned long		end;
+	size_t			pgsize;
+};
+
+/**
  * struct iommu_ops - iommu ops and capabilities
  * @capable: check capability
  * @domain_alloc: allocate iommu domain
@@ -375,6 +392,13 @@ static inline struct iommu_device *dev_to_iommu_device(struct device *dev)
 	return (struct iommu_device *)dev_get_drvdata(dev);
 }
 
+static inline void iommu_iotlb_gather_init(struct iommu_iotlb_gather *gather)
+{
+	*gather = (struct iommu_iotlb_gather) {
+		.start	= ULONG_MAX,
+	};
+}
+
 #define IOMMU_GROUP_NOTIFY_ADD_DEVICE		1 /* Device added */
 #define IOMMU_GROUP_NOTIFY_DEL_DEVICE		2 /* Pre Device removed */
 #define IOMMU_GROUP_NOTIFY_BIND_DRIVER		3 /* Pre Driver bind */
@@ -399,7 +423,8 @@ extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
 extern size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova,
 			  size_t size);
 extern size_t iommu_unmap_fast(struct iommu_domain *domain,
-			       unsigned long iova, size_t size);
+			       unsigned long iova, size_t size,
+			       struct iommu_iotlb_gather *iotlb_gather);
 extern size_t iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
 			   struct scatterlist *sg,unsigned int nents, int prot);
 extern phys_addr_t iommu_iova_to_phys(struct iommu_domain *domain, dma_addr_t iova);
@@ -473,10 +498,13 @@ static inline void iommu_flush_tlb_all(struct iommu_domain *domain)
 		domain->ops->flush_iotlb_all(domain);
 }
 
-static inline void iommu_tlb_sync(struct iommu_domain *domain)
+static inline void iommu_tlb_sync(struct iommu_domain *domain,
+				  struct iommu_iotlb_gather *iotlb_gather)
 {
 	if (domain->ops->iotlb_sync)
 		domain->ops->iotlb_sync(domain);
+
+	iommu_iotlb_gather_init(iotlb_gather);
 }
 
 /* PCI device grouping function */
@@ -557,6 +585,7 @@ struct iommu_group {};
 struct iommu_fwspec {};
 struct iommu_device {};
 struct iommu_fault_param {};
+struct iommu_iotlb_gather {};
 
 static inline bool iommu_present(struct bus_type *bus)
 {
@@ -611,7 +640,8 @@ static inline size_t iommu_unmap(struct iommu_domain *domain,
 }
 
 static inline size_t iommu_unmap_fast(struct iommu_domain *domain,
-				      unsigned long iova, int gfp_order)
+				      unsigned long iova, int gfp_order,
+				      struct iommu_iotlb_gather *iotlb_gather)
 {
 	return 0;
 }
@@ -627,7 +657,8 @@ static inline void iommu_flush_tlb_all(struct iommu_domain *domain)
 {
 }
 
-static inline void iommu_tlb_sync(struct iommu_domain *domain)
+static inline void iommu_tlb_sync(struct iommu_domain *domain,
+				  struct iommu_iotlb_gather *iotlb_gather)
 {
 }
 
@@ -812,6 +843,10 @@ static inline struct iommu_device *dev_to_iommu_device(struct device *dev)
 	return NULL;
 }
 
+static inline void iommu_iotlb_gather_init(struct iommu_iotlb_gather *gather)
+{
+}
+
 static inline void iommu_device_unregister(struct iommu_device *iommu)
 {
 }