IB/{rxe,core,rdmavt}: Fix kernel crash for reg MR

This patch fixes below kernel crash on memory registration for rxe
and other transport drivers which has dma_ops extension.

IB/core invokes ib_map_sg_attrs() in generic manner with dma attributes
which is used by mlx5 and mthca adapters.  However in doing so it
ignored honoring dma_ops extension of software based transports for
sg map/unmap operation.  This results in calling dma_map_sg_attrs of
hardware virtual device resulting in crash for null reference.

We extend the core to support sg_map/unmap_attrs and transport drivers
to implement those dma_ops callback functions.

Verified usign perftest applications.

BUG: unable to handle kernel NULL pointer dereference at           (null)
IP: [<ffffffff81032a75>] check_addr+0x35/0x60
...
Call Trace:
 [<ffffffff81032b39>] ? nommu_map_sg+0x99/0xd0
 [<ffffffffa02b31c6>] ib_umem_get+0x3d6/0x470 [ib_core]
 [<ffffffffa01cc329>] rxe_mem_init_user+0x49/0x270 [rdma_rxe]
 [<ffffffffa01c793a>] ? rxe_add_index+0xca/0x100 [rdma_rxe]
 [<ffffffffa01c995f>] rxe_reg_user_mr+0x9f/0x130 [rdma_rxe]
 [<ffffffffa00419fe>] ib_uverbs_reg_mr+0x14e/0x2c0 [ib_uverbs]
 [<ffffffffa003d3ab>] ib_uverbs_write+0x15b/0x3b0 [ib_uverbs]
 [<ffffffff811e92a6>] ? mem_cgroup_commit_charge+0x76/0xe0
 [<ffffffff811af0a9>] ? page_add_new_anon_rmap+0x89/0xc0
 [<ffffffff8117e6c9>] ? lru_cache_add_active_or_unevictable+0x39/0xc0
 [<ffffffff811f0da8>] __vfs_write+0x28/0x120
 [<ffffffff811f1239>] ? rw_verify_area+0x49/0xb0
 [<ffffffff811f1492>] vfs_write+0xb2/0x1b0
 [<ffffffff811f27d6>] SyS_write+0x46/0xa0
 [<ffffffff814f7d32>] entry_SYSCALL_64_fastpath+0x1a/0xa4

Signed-off-by: Parav Pandit <pandit.parav@gmail.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/sw/rdmavt/dma.c

@@ -138,6 +138,21 @@ static void rvt_unmap_sg(struct ib_device *dev,
 	/* This is a stub, nothing to be done here */
 }
 
+static int rvt_map_sg_attrs(struct ib_device *dev, struct scatterlist *sgl,
+			    int nents, enum dma_data_direction direction,
+			    unsigned long attrs)
+{
+	return rvt_map_sg(dev, sgl, nents, direction);
+}
+
+static void rvt_unmap_sg_attrs(struct ib_device *dev,
+			       struct scatterlist *sg, int nents,
+			       enum dma_data_direction direction,
+			       unsigned long attrs)
+{
+	return rvt_unmap_sg(dev, sg, nents, direction);
+}
+
 static void rvt_sync_single_for_cpu(struct ib_device *dev, u64 addr,
 				    size_t size, enum dma_data_direction dir)
 {
@@ -177,6 +192,8 @@ struct ib_dma_mapping_ops rvt_default_dma_mapping_ops = {
 	.unmap_page = rvt_dma_unmap_page,
 	.map_sg = rvt_map_sg,
 	.unmap_sg = rvt_unmap_sg,
+	.map_sg_attrs = rvt_map_sg_attrs,
+	.unmap_sg_attrs = rvt_unmap_sg_attrs,
 	.sync_single_for_cpu = rvt_sync_single_for_cpu,
 	.sync_single_for_device = rvt_sync_single_for_device,
 	.alloc_coherent = rvt_dma_alloc_coherent,

drivers/infiniband/sw/rxe/rxe_dma.c

@@ -117,6 +117,21 @@ static void rxe_unmap_sg(struct ib_device *dev,
 	WARN_ON(!valid_dma_direction(direction));
 }
 
+static int rxe_map_sg_attrs(struct ib_device *dev, struct scatterlist *sgl,
+			    int nents, enum dma_data_direction direction,
+			    unsigned long attrs)
+{
+	return rxe_map_sg(dev, sgl, nents, direction);
+}
+
+static void rxe_unmap_sg_attrs(struct ib_device *dev,
+			       struct scatterlist *sg, int nents,
+			       enum dma_data_direction direction,
+			       unsigned long attrs)
+{
+	rxe_unmap_sg(dev, sg, nents, direction);
+}
+
 static void rxe_sync_single_for_cpu(struct ib_device *dev,
 				    u64 addr,
 				    size_t size, enum dma_data_direction dir)
@@ -159,6 +174,8 @@ struct ib_dma_mapping_ops rxe_dma_mapping_ops = {
 	.unmap_page		= rxe_dma_unmap_page,
 	.map_sg			= rxe_map_sg,
 	.unmap_sg		= rxe_unmap_sg,
+	.map_sg_attrs		= rxe_map_sg_attrs,
+	.unmap_sg_attrs		= rxe_unmap_sg_attrs,
 	.sync_single_for_cpu	= rxe_sync_single_for_cpu,
 	.sync_single_for_device	= rxe_sync_single_for_device,
 	.alloc_coherent		= rxe_dma_alloc_coherent,

include/rdma/ib_verbs.h

@@ -1739,6 +1739,14 @@ struct ib_dma_mapping_ops {
 	void		(*unmap_sg)(struct ib_device *dev,
 				    struct scatterlist *sg, int nents,
 				    enum dma_data_direction direction);
+	int		(*map_sg_attrs)(struct ib_device *dev,
+					struct scatterlist *sg, int nents,
+					enum dma_data_direction direction,
+					unsigned long attrs);
+	void		(*unmap_sg_attrs)(struct ib_device *dev,
+					  struct scatterlist *sg, int nents,
+					  enum dma_data_direction direction,
+					  unsigned long attrs);
 	void		(*sync_single_for_cpu)(struct ib_device *dev,
 					       u64 dma_handle,
 					       size_t size,
@@ -3000,8 +3008,12 @@ static inline int ib_dma_map_sg_attrs(struct ib_device *dev,
 				      enum dma_data_direction direction,
 				      unsigned long dma_attrs)
 {
-	return dma_map_sg_attrs(dev->dma_device, sg, nents, direction,
-				dma_attrs);
+	if (dev->dma_ops)
+		return dev->dma_ops->map_sg_attrs(dev, sg, nents, direction,
+						  dma_attrs);
+	else
+		return dma_map_sg_attrs(dev->dma_device, sg, nents, direction,
+					dma_attrs);
 }
 
 static inline void ib_dma_unmap_sg_attrs(struct ib_device *dev,
@@ -3009,7 +3021,12 @@ static inline void ib_dma_unmap_sg_attrs(struct ib_device *dev,
 					 enum dma_data_direction direction,
 					 unsigned long dma_attrs)
 {
-	dma_unmap_sg_attrs(dev->dma_device, sg, nents, direction, dma_attrs);
+	if (dev->dma_ops)
+		return dev->dma_ops->unmap_sg_attrs(dev, sg, nents, direction,
+						  dma_attrs);
+	else
+		dma_unmap_sg_attrs(dev->dma_device, sg, nents, direction,
+				   dma_attrs);
 }
 /**
  * ib_sg_dma_address - Return the DMA address from a scatter/gather entry