Re: [PATCH kernel v5 03/20] powerpc/vfio/iommu/kvm: Do not pin device memory

diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index f0dc680..cbcc615 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c

@@ -993,15 +994,19 @@ int iommu_tce_check_gpa(unsigned long page_shift, unsigned long gpa)
 }
 EXPORT_SYMBOL_GPL(iommu_tce_check_gpa);
 
-long iommu_tce_xchg(struct iommu_table *tbl, unsigned long entry,
-		unsigned long *hpa, enum dma_data_direction *direction)
+long iommu_tce_xchg(struct mm_struct *mm, struct iommu_table *tbl,
+		unsigned long entry, unsigned long *hpa,
+		enum dma_data_direction *direction)
 {
 	long ret;
+	unsigned long size = 0;
 
 	ret = tbl->it_ops->exchange(tbl, entry, hpa, direction);
 
 	if (!ret && ((*direction == DMA_FROM_DEVICE) ||
-			(*direction == DMA_BIDIRECTIONAL)))
+			(*direction == DMA_BIDIRECTIONAL)) &&
+			!mm_iommu_is_devmem(mm, *hpa, tbl->it_page_shift,
+					&size))

diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
index 25a4b7f7..06fdbd3 100644
--- a/arch/powerpc/mm/mmu_context_iommu.c
+++ b/arch/powerpc/mm/mmu_context_iommu.c

@@ -384,6 +432,33 @@ extern void mm_iommu_ua_mark_dirty_rm(struct mm_struct *mm, unsigned long ua)
 	*pa |= MM_IOMMU_TABLE_GROUP_PAGE_DIRTY;
 }
 
+extern bool mm_iommu_is_devmem(struct mm_struct *mm, unsigned long hpa,
+		unsigned int pageshift, unsigned long *size)
+{