IB/core: Restore I/O MMU, s390 and powerpc support

Avoid that the following error message is reported on the console
while loading an RDMA driver with I/O MMU support enabled:

DMAR: Allocating domain for mlx5_0 failed

Ensure that DMA mapping operations that use to_pci_dev() to
access to struct pci_dev see the correct PCI device. E.g. the s390
and powerpc DMA mapping operations use to_pci_dev() even with I/O
MMU support disabled.

This patch preserves the following changes of the DMA mapping updates
patch series:
- Introduction of dma_virt_ops.
- Removal of ib_device.dma_ops.
- Removal of struct ib_dma_mapping_ops.
- Removal of an if-statement from each ib_dma_*() operation.
- IB HW drivers no longer set dma_device directly.

Reported-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Reported-by: Parav Pandit <parav@mellanox.com>
Fixes: commit 99db9494035f ("IB/core: Remove ib_device.dma_device")
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: parav@mellanox.com
Tested-by: parav@mellanox.com
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

1 files changed, 20 insertions, 6 deletions

diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
index 593d2ce6ec7c..addf869045cc 100644
--- a/drivers/infiniband/core/device.c
+++ b/drivers/infiniband/core/device.c
@@ -336,12 +336,26 @@ int ib_register_device(struct ib_device *device,
 	struct device *parent = device->dev.parent;
 
 	WARN_ON_ONCE(!parent);
-	if (!device->dev.dma_ops)
-		device->dev.dma_ops = parent->dma_ops;
-	if (!device->dev.dma_mask)
-		device->dev.dma_mask = parent->dma_mask;
-	if (!device->dev.coherent_dma_mask)
-		device->dev.coherent_dma_mask = parent->coherent_dma_mask;
+	WARN_ON_ONCE(device->dma_device);
+	if (device->dev.dma_ops) {
+		/*
+		 * The caller provided custom DMA operations. Copy the
+		 * DMA-related fields that are used by e.g. dma_alloc_coherent()
+		 * into device->dev.
+		 */
+		device->dma_device = &device->dev;
+		if (!device->dev.dma_mask)
+			device->dev.dma_mask = parent->dma_mask;
+		if (!device->dev.coherent_dma_mask)
+			device->dev.coherent_dma_mask =
+				parent->coherent_dma_mask;
+	} else {
+		/*
+		 * The caller did not provide custom DMA operations. Use the
+		 * DMA mapping operations of the parent device.
+		 */
+		device->dma_device = parent;
+	}
 
 	mutex_lock(&device_mutex);