iommu: Restore iommu_flush_iotlb_all()

This patch restores the iommu_flush_iotlb_all() function.
Commit

	69e5a17 ("iommu: Remove useless flush from iommu_create_device_direct_mappings()")

claims it removed the last call-site, except it did not. There is still
at least one caller in

	drivers/gpu/drm/msm/msm_iommu.c

so keep the function around until all call-sites are updated.

Cc: Jason Gunthorpe <jgg@ziepe.ca>
Fixes: 69e5a17 ("iommu: Remove useless flush from iommu_create_device_direct_mappings()")
Acked-by: Will Deacon <will@kernel.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

Author: joergroedel

include/linux/iommu.h

@@ -853,6 +853,12 @@ void iommu_set_dma_strict(void);
 extern int report_iommu_fault(struct iommu_domain *domain, struct device *dev,
 			      unsigned long iova, int flags);
 
+static inline void iommu_flush_iotlb_all(struct iommu_domain *domain)
+{
+	if (domain->ops->flush_iotlb_all)
+		domain->ops->flush_iotlb_all(domain);
+}
+
 static inline void iommu_iotlb_sync(struct iommu_domain *domain,
 				  struct iommu_iotlb_gather *iotlb_gather)
 {
@@ -1137,6 +1143,10 @@ static inline ssize_t iommu_map_sg(struct iommu_domain *domain,
 	return -ENODEV;
 }
 
+static inline void iommu_flush_iotlb_all(struct iommu_domain *domain)
+{
+}
+
 static inline void iommu_iotlb_sync(struct iommu_domain *domain,
 				  struct iommu_iotlb_gather *iotlb_gather)
 {