iommu: Introduce Interface for IOMMU TLB Flushing

With the current IOMMU-API the hardware TLBs have to be flushed in every iommu_ops->unmap() call-back. For unmapping large amounts of address space, like it happens when a KVM domain with assigned devices is destroyed, this causes thousands of unnecessary TLB flushes in the IOMMU hardware because the unmap call-back runs for every unmapped physical page. With the TLB Flush Interface and the new iommu_unmap_fast() function introduced here the need to clean the hardware TLBs is removed from the unmapping code-path. Users of iommu_unmap_fast() have to explicitly call the TLB-Flush functions to sync the page-table changes to the hardware. Three functions for TLB-Flushes are introduced: * iommu_flush_tlb_all() - Flushes all TLB entries associated with that domain. TLBs entries are flushed when this function returns. * iommu_tlb_range_add() - This will add a given range to the flush queue for this domain. * iommu_tlb_sync() - Flushes all queued ranges from the hardware TLBs. Returns when the flush is finished. The semantic of this interface is intentionally similar to the iommu_gather_ops from the io-pgtable code. Cc: Alex Williamson <[email protected]> Cc: Will Deacon <[email protected]> Cc: Robin Murphy <[email protected]> Signed-off-by: Joerg Roedel <[email protected]>
vieko · Aug 30, 2017 · add02cf · add02cf
1 parent 0688a09
commit add02cf
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Showing 2 changed files with 77 additions and 5 deletions.
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
@@ -527,6 +527,8 @@ static int iommu_group_create_direct_mappings(struct iommu_group *group,
 
 	}
 
+	iommu_flush_tlb_all(domain);
+
 out:
 	iommu_put_resv_regions(dev, &mappings);
 
@@ -1547,13 +1549,16 @@ int iommu_map(struct iommu_domain *domain, unsigned long iova,
 }
 EXPORT_SYMBOL_GPL(iommu_map);
 
-size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
+static size_t __iommu_unmap(struct iommu_domain *domain,
+			    unsigned long iova, size_t size,
+			    bool sync)
 {
+	const struct iommu_ops *ops = domain->ops;
 	size_t unmapped_page, unmapped = 0;
-	unsigned int min_pagesz;
 	unsigned long orig_iova = iova;
+	unsigned int min_pagesz;
 
-	if (unlikely(domain->ops->unmap == NULL ||
+	if (unlikely(ops->unmap == NULL ||
 		     domain->pgsize_bitmap == 0UL))
 		return -ENODEV;
 
@@ -1583,22 +1588,41 @@ size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova, size_t size)
 	while (unmapped < size) {
 		size_t pgsize = iommu_pgsize(domain, iova, size - unmapped);
 
-		unmapped_page = domain->ops->unmap(domain, iova, pgsize);
+		unmapped_page = ops->unmap(domain, iova, pgsize);
 		if (!unmapped_page)
 			break;
 
+		if (sync && ops->iotlb_range_add)
+			ops->iotlb_range_add(domain, iova, pgsize);
+
 		pr_debug("unmapped: iova 0x%lx size 0x%zx\n",
 			 iova, unmapped_page);
 
 		iova += unmapped_page;
 		unmapped += unmapped_page;
 	}
 
+	if (sync && ops->iotlb_sync)
+		ops->iotlb_sync(domain);
+
 	trace_unmap(orig_iova, size, unmapped);
 	return unmapped;
 }
+
+size_t iommu_unmap(struct iommu_domain *domain,
+		   unsigned long iova, size_t size)
+{
+	return __iommu_unmap(domain, iova, size, true);
+}
 EXPORT_SYMBOL_GPL(iommu_unmap);
 
+size_t iommu_unmap_fast(struct iommu_domain *domain,
+			unsigned long iova, size_t size)
+{
+	return __iommu_unmap(domain, iova, size, false);
+}
+EXPORT_SYMBOL_GPL(iommu_unmap_fast);
+
 size_t default_iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
 			 struct scatterlist *sg, unsigned int nents, int prot)
 {

diff --git a/include/linux/iommu.h b/include/linux/iommu.h
@@ -167,6 +167,10 @@ struct iommu_resv_region {
  * @map: map a physically contiguous memory region to an iommu domain
  * @unmap: unmap a physically contiguous memory region from an iommu domain
  * @map_sg: map a scatter-gather list of physically contiguous memory chunks
+ * @flush_tlb_all: Synchronously flush all hardware TLBs for this domain
+ * @tlb_range_add: Add a given iova range to the flush queue for this domain
+ * @tlb_sync: Flush all queued ranges from the hardware TLBs and empty flush
+ *            queue
  * to an iommu domain
  * @iova_to_phys: translate iova to physical address
  * @add_device: add device to iommu grouping
@@ -199,6 +203,10 @@ struct iommu_ops {
 		     size_t size);
 	size_t (*map_sg)(struct iommu_domain *domain, unsigned long iova,
 			 struct scatterlist *sg, unsigned int nents, int prot);
+	void (*flush_iotlb_all)(struct iommu_domain *domain);
+	void (*iotlb_range_add)(struct iommu_domain *domain,
+				unsigned long iova, size_t size);
+	void (*iotlb_sync)(struct iommu_domain *domain);
 	phys_addr_t (*iova_to_phys)(struct iommu_domain *domain, dma_addr_t iova);
 	int (*add_device)(struct device *dev);
 	void (*remove_device)(struct device *dev);
@@ -286,7 +294,9 @@ extern struct iommu_domain *iommu_get_domain_for_dev(struct device *dev);
 extern int iommu_map(struct iommu_domain *domain, unsigned long iova,
 		     phys_addr_t paddr, size_t size, int prot);
 extern size_t iommu_unmap(struct iommu_domain *domain, unsigned long iova,
-		       size_t size);
+			  size_t size);
+extern size_t iommu_unmap_fast(struct iommu_domain *domain,
+			       unsigned long iova, size_t size);
 extern size_t default_iommu_map_sg(struct iommu_domain *domain, unsigned long iova,
 				struct scatterlist *sg,unsigned int nents,
 				int prot);
@@ -343,6 +353,25 @@ extern void iommu_domain_window_disable(struct iommu_domain *domain, u32 wnd_nr)
 extern int report_iommu_fault(struct iommu_domain *domain, struct device *dev,
 			      unsigned long iova, int flags);
 
+static inline void iommu_flush_tlb_all(struct iommu_domain *domain)
+{
+	if (domain->ops->flush_iotlb_all)
+		domain->ops->flush_iotlb_all(domain);
+}
+
+static inline void iommu_tlb_range_add(struct iommu_domain *domain,
+				       unsigned long iova, size_t size)
+{
+	if (domain->ops->iotlb_range_add)
+		domain->ops->iotlb_range_add(domain, iova, size);
+}
+
+static inline void iommu_tlb_sync(struct iommu_domain *domain)
+{
+	if (domain->ops->iotlb_sync)
+		domain->ops->iotlb_sync(domain);
+}
+
 static inline size_t iommu_map_sg(struct iommu_domain *domain,
 				  unsigned long iova, struct scatterlist *sg,
 				  unsigned int nents, int prot)
@@ -436,13 +465,32 @@ static inline int iommu_unmap(struct iommu_domain *domain, unsigned long iova,
 	return -ENODEV;
 }
 
+static inline int iommu_unmap_fast(struct iommu_domain *domain, unsigned long iova,
+				   int gfp_order)
+{
+	return -ENODEV;
+}
+
 static inline size_t iommu_map_sg(struct iommu_domain *domain,
 				  unsigned long iova, struct scatterlist *sg,
 				  unsigned int nents, int prot)
 {
 	return -ENODEV;
 }
 
+static inline void iommu_flush_tlb_all(struct iommu_domain *domain)
+{
+}
+
+static inline void iommu_tlb_range_add(struct iommu_domain *domain,
+				       unsigned long iova, size_t size)
+{
+}
+
+static inline void iommu_tlb_sync(struct iommu_domain *domain)
+{
+}
+
 static inline int iommu_domain_window_enable(struct iommu_domain *domain,
 					     u32 wnd_nr, phys_addr_t paddr,
 					     u64 size, int prot)