vfio: powerpc/spapr: Move page pinning from arch code to VFIO IOMMU driver

This moves page pinning (get_user_pages_fast()/put_page()) code out of
the platform IOMMU code and puts it to VFIO IOMMU driver where it belongs
to as the platform code does not deal with page pinning.

This makes iommu_take_ownership()/iommu_release_ownership() deal with
the IOMMU table bitmap only.

This removes page unpinning from iommu_take_ownership() as the actual
TCE table might contain garbage and doing put_page() on it is undefined
behaviour.

Besides the last part, the rest of the patch is mechanical.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
[aw: for the vfio related changes]
Acked-by: Alex Williamson <alex.williamson@redhat.com>
Reviewed-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Gavin Shan <gwshan@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 67 insertions, 13 deletions

diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index 730b4ef3e0cc..b95fa2b64680 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -147,6 +147,67 @@ static void tce_iommu_release(void *iommu_data)
 	kfree(container);
 }
 
+static int tce_iommu_clear(struct tce_container *container,
+		struct iommu_table *tbl,
+		unsigned long entry, unsigned long pages)
+{
+	unsigned long oldtce;
+	struct page *page;
+
+	for ( ; pages; --pages, ++entry) {
+		oldtce = iommu_clear_tce(tbl, entry);
+		if (!oldtce)
+			continue;
+
+		page = pfn_to_page(oldtce >> PAGE_SHIFT);
+		WARN_ON(!page);
+		if (page) {
+			if (oldtce & TCE_PCI_WRITE)
+				SetPageDirty(page);
+			put_page(page);
+		}
+	}
+
+	return 0;
+}
+
+static long tce_iommu_build(struct tce_container *container,
+		struct iommu_table *tbl,
+		unsigned long entry, unsigned long tce, unsigned long pages)
+{
+	long i, ret = 0;
+	struct page *page = NULL;
+	unsigned long hva;
+	enum dma_data_direction direction = iommu_tce_direction(tce);
+
+	for (i = 0; i < pages; ++i) {
+		unsigned long offset = tce & IOMMU_PAGE_MASK(tbl) & ~PAGE_MASK;
+
+		ret = get_user_pages_fast(tce & PAGE_MASK, 1,
+				direction != DMA_TO_DEVICE, &page);
+		if (unlikely(ret != 1)) {
+			ret = -EFAULT;
+			break;
+		}
+		hva = (unsigned long) page_address(page) + offset;
+
+		ret = iommu_tce_build(tbl, entry + i, hva, direction);
+		if (ret) {
+			put_page(page);
+			pr_err("iommu_tce: %s failed ioba=%lx, tce=%lx, ret=%ld\n",
+					__func__, entry << tbl->it_page_shift,
+					tce, ret);
+			break;
+		}
+		tce += IOMMU_PAGE_SIZE_4K;
+	}
+
+	if (ret)
+		tce_iommu_clear(container, tbl, entry, i);
+
+	return ret;
+}
+
 static long tce_iommu_ioctl(void *iommu_data,
 				 unsigned int cmd, unsigned long arg)
 {
@@ -195,7 +256,7 @@ static long tce_iommu_ioctl(void *iommu_data,
 	case VFIO_IOMMU_MAP_DMA: {
 		struct vfio_iommu_type1_dma_map param;
 		struct iommu_table *tbl = container->tbl;
-		unsigned long tce, i;
+		unsigned long tce;
 
 		if (!tbl)
 			return -ENXIO;
@@ -229,17 +290,9 @@ static long tce_iommu_ioctl(void *iommu_data,
 		if (ret)
 			return ret;
 
-		for (i = 0; i < (param.size >> IOMMU_PAGE_SHIFT_4K); ++i) {
-			ret = iommu_put_tce_user_mode(tbl,
-					(param.iova >> IOMMU_PAGE_SHIFT_4K) + i,
-					tce);
-			if (ret)
-				break;
-			tce += IOMMU_PAGE_SIZE_4K;
-		}
-		if (ret)
-			iommu_clear_tces_and_put_pages(tbl,
-					param.iova >> IOMMU_PAGE_SHIFT_4K, i);
+		ret = tce_iommu_build(container, tbl,
+				param.iova >> IOMMU_PAGE_SHIFT_4K,
+				tce, param.size >> IOMMU_PAGE_SHIFT_4K);
 
 		iommu_flush_tce(tbl);
 
@@ -273,7 +326,7 @@ static long tce_iommu_ioctl(void *iommu_data,
 		if (ret)
 			return ret;
 
-		ret = iommu_clear_tces_and_put_pages(tbl,
+		ret = tce_iommu_clear(container, tbl,
 				param.iova >> IOMMU_PAGE_SHIFT_4K,
 				param.size >> IOMMU_PAGE_SHIFT_4K);
 		iommu_flush_tce(tbl);
@@ -357,6 +410,7 @@ static void tce_iommu_detach_group(void *iommu_data,
 		/* pr_debug("tce_vfio: detaching group #%u from iommu %p\n",
 				iommu_group_id(iommu_group), iommu_group); */
 		container->tbl = NULL;
+		tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
 		iommu_release_ownership(tbl);
 	}
 	mutex_unlock(&container->lock);