IB/ehca: Tolerate dynamic memory operations before driver load

Implement toleration of dynamic memory operations and 16 GB gigantic
pages, where "toleration" means that the driver can cope with dynamic
memory operations that happen before the driver is loaded.  While the
ehca driver is loaded, dynamic memory operations are still prohibited
by returning NOTIFY_BAD from the memory notifier.

On module load the driver walks through available system memory,
checks for available memory ranges and then registers the kernel
internal memory region accordingly.  The translation of address ranges
is implemented via a 3-level busmap.

Signed-off-by: Hannes Hering <hering2@de.ibm.com>
Signed-off-by: Roland Dreier <rolandd@cisco.com>

3 files changed, 522 insertions, 17 deletions

diff --git a/drivers/infiniband/hw/ehca/ehca_main.c b/drivers/infiniband/hw/ehca/ehca_main.c
index ce4e6eff4792..14a18b7be245 100644
--- a/drivers/infiniband/hw/ehca/ehca_main.c
+++ b/drivers/infiniband/hw/ehca/ehca_main.c
@@ -506,6 +506,7 @@ static int ehca_init_device(struct ehca_shca *shca)
 	shca->ib_device.detach_mcast	    = ehca_detach_mcast;
 	shca->ib_device.process_mad	    = ehca_process_mad;
 	shca->ib_device.mmap		    = ehca_mmap;
+	shca->ib_device.dma_ops		    = &ehca_dma_mapping_ops;
 
 	if (EHCA_BMASK_GET(HCA_CAP_SRQ, shca->hca_cap)) {
 		shca->ib_device.uverbs_cmd_mask |=
@@ -1028,17 +1029,23 @@ static int __init ehca_module_init(void)
 		goto module_init1;
 	}
 
+	ret = ehca_create_busmap();
+	if (ret) {
+		ehca_gen_err("Cannot create busmap.");
+		goto module_init2;
+	}
+
 	ret = ibmebus_register_driver(&ehca_driver);
 	if (ret) {
 		ehca_gen_err("Cannot register eHCA device driver");
 		ret = -EINVAL;
-		goto module_init2;
+		goto module_init3;
 	}
 
 	ret = register_memory_notifier(&ehca_mem_nb);
 	if (ret) {
 		ehca_gen_err("Failed registering memory add/remove notifier");
-		goto module_init3;
+		goto module_init4;
 	}
 
 	if (ehca_poll_all_eqs != 1) {
@@ -1053,9 +1060,12 @@ static int __init ehca_module_init(void)
 
 	return 0;
 
-module_init3:
+module_init4:
 	ibmebus_unregister_driver(&ehca_driver);
 
+module_init3:
+	ehca_destroy_busmap();
+
 module_init2:
 	ehca_destroy_slab_caches();
 
@@ -1073,6 +1083,8 @@ static void __exit ehca_module_exit(void)
 
 	unregister_memory_notifier(&ehca_mem_nb);
 
+	ehca_destroy_busmap();
+
 	ehca_destroy_slab_caches();
 
 	ehca_destroy_comp_pool();
diff --git a/drivers/infiniband/hw/ehca/ehca_mrmw.c b/drivers/infiniband/hw/ehca/ehca_mrmw.c
index 72f83f7df614..7663a2a9f130 100644
--- a/drivers/infiniband/hw/ehca/ehca_mrmw.c
+++ b/drivers/infiniband/hw/ehca/ehca_mrmw.c
@@ -53,6 +53,38 @@
 /* max number of rpages (per hcall register_rpages) */
 #define MAX_RPAGES 512
 
+/* DMEM toleration management */
+#define EHCA_SECTSHIFT        SECTION_SIZE_BITS
+#define EHCA_SECTSIZE          (1UL << EHCA_SECTSHIFT)
+#define EHCA_HUGEPAGESHIFT     34
+#define EHCA_HUGEPAGE_SIZE     (1UL << EHCA_HUGEPAGESHIFT)
+#define EHCA_HUGEPAGE_PFN_MASK ((EHCA_HUGEPAGE_SIZE - 1) >> PAGE_SHIFT)
+#define EHCA_INVAL_ADDR        0xFFFFFFFFFFFFFFFFULL
+#define EHCA_DIR_INDEX_SHIFT 13                   /* 8k Entries in 64k block */
+#define EHCA_TOP_INDEX_SHIFT (EHCA_DIR_INDEX_SHIFT * 2)
+#define EHCA_MAP_ENTRIES (1 << EHCA_DIR_INDEX_SHIFT)
+#define EHCA_TOP_MAP_SIZE (0x10000)               /* currently fixed map size */
+#define EHCA_DIR_MAP_SIZE (0x10000)
+#define EHCA_ENT_MAP_SIZE (0x10000)
+#define EHCA_INDEX_MASK (EHCA_MAP_ENTRIES - 1)
+
+static unsigned long ehca_mr_len;
+
+/*
+ * Memory map data structures
+ */
+struct ehca_dir_bmap {
+	u64 ent[EHCA_MAP_ENTRIES];
+};
+struct ehca_top_bmap {
+	struct ehca_dir_bmap *dir[EHCA_MAP_ENTRIES];
+};
+struct ehca_bmap {
+	struct ehca_top_bmap *top[EHCA_MAP_ENTRIES];
+};
+
+static struct ehca_bmap *ehca_bmap;
+
 static struct kmem_cache *mr_cache;
 static struct kmem_cache *mw_cache;
 
@@ -68,6 +100,8 @@ enum ehca_mr_pgsize {
 #define EHCA_MR_PGSHIFT1M  20
 #define EHCA_MR_PGSHIFT16M 24
 
+static u64 ehca_map_vaddr(void *caddr);
+
 static u32 ehca_encode_hwpage_size(u32 pgsize)
 {
 	int log = ilog2(pgsize);
@@ -135,7 +169,8 @@ struct ib_mr *ehca_get_dma_mr(struct ib_pd *pd, int mr_access_flags)
 			goto get_dma_mr_exit0;
 		}
 
-		ret = ehca_reg_maxmr(shca, e_maxmr, (u64 *)KERNELBASE,
+		ret = ehca_reg_maxmr(shca, e_maxmr,
+				     (void *)ehca_map_vaddr((void *)KERNELBASE),
 				     mr_access_flags, e_pd,
 				     &e_maxmr->ib.ib_mr.lkey,
 				     &e_maxmr->ib.ib_mr.rkey);
@@ -251,7 +286,7 @@ struct ib_mr *ehca_reg_phys_mr(struct ib_pd *pd,
 
 		ret = ehca_reg_mr(shca, e_mr, iova_start, size, mr_access_flags,
 				  e_pd, &pginfo, &e_mr->ib.ib_mr.lkey,
-				  &e_mr->ib.ib_mr.rkey);
+				  &e_mr->ib.ib_mr.rkey, EHCA_REG_MR);
 		if (ret) {
 			ib_mr = ERR_PTR(ret);
 			goto reg_phys_mr_exit1;
@@ -370,7 +405,7 @@ reg_user_mr_fallback:
 
 	ret = ehca_reg_mr(shca, e_mr, (u64 *)virt, length, mr_access_flags,
 			  e_pd, &pginfo, &e_mr->ib.ib_mr.lkey,
-			  &e_mr->ib.ib_mr.rkey);
+			  &e_mr->ib.ib_mr.rkey, EHCA_REG_MR);
 	if (ret == -EINVAL && pginfo.hwpage_size > PAGE_SIZE) {
 		ehca_warn(pd->device, "failed to register mr "
 			  "with hwpage_size=%llx", hwpage_size);
@@ -794,7 +829,7 @@ struct ib_fmr *ehca_alloc_fmr(struct ib_pd *pd,
 	ret = ehca_reg_mr(shca, e_fmr, NULL,
 			  fmr_attr->max_pages * (1 << fmr_attr->page_shift),
 			  mr_access_flags, e_pd, &pginfo,
-			  &tmp_lkey, &tmp_rkey);
+			  &tmp_lkey, &tmp_rkey, EHCA_REG_MR);
 	if (ret) {
 		ib_fmr = ERR_PTR(ret);
 		goto alloc_fmr_exit1;
@@ -983,6 +1018,10 @@ free_fmr_exit0:
 
 /*----------------------------------------------------------------------*/
 
+static int ehca_reg_bmap_mr_rpages(struct ehca_shca *shca,
+				   struct ehca_mr *e_mr,
+				   struct ehca_mr_pginfo *pginfo);
+
 int ehca_reg_mr(struct ehca_shca *shca,
 		struct ehca_mr *e_mr,
 		u64 *iova_start,
@@ -991,7 +1030,8 @@ int ehca_reg_mr(struct ehca_shca *shca,
 		struct ehca_pd *e_pd,
 		struct ehca_mr_pginfo *pginfo,
 		u32 *lkey, /*OUT*/
-		u32 *rkey) /*OUT*/
+		u32 *rkey, /*OUT*/
+		enum ehca_reg_type reg_type)
 {
 	int ret;
 	u64 h_ret;
@@ -1015,7 +1055,13 @@ int ehca_reg_mr(struct ehca_shca *shca,
 
 	e_mr->ipz_mr_handle = hipzout.handle;
 
-	ret = ehca_reg_mr_rpages(shca, e_mr, pginfo);
+	if (reg_type == EHCA_REG_BUSMAP_MR)
+		ret = ehca_reg_bmap_mr_rpages(shca, e_mr, pginfo);
+	else if (reg_type == EHCA_REG_MR)
+		ret = ehca_reg_mr_rpages(shca, e_mr, pginfo);
+	else
+		ret = -EINVAL;
+
 	if (ret)
 		goto ehca_reg_mr_exit1;
 
@@ -1316,7 +1362,7 @@ int ehca_rereg_mr(struct ehca_shca *shca,
 		e_mr->fmr_map_cnt = save_mr.fmr_map_cnt;
 
 		ret = ehca_reg_mr(shca, e_mr, iova_start, size, acl,
-				  e_pd, pginfo, lkey, rkey);
+				  e_pd, pginfo, lkey, rkey, EHCA_REG_MR);
 		if (ret) {
 			u32 offset = (u64)(&e_mr->flags) - (u64)e_mr;
 			memcpy(&e_mr->flags, &(save_mr.flags),
@@ -1409,7 +1455,7 @@ int ehca_unmap_one_fmr(struct ehca_shca *shca,
 	ret = ehca_reg_mr(shca, e_fmr, NULL,
 			  (e_fmr->fmr_max_pages * e_fmr->fmr_page_size),
 			  e_fmr->acl, e_pd, &pginfo, &tmp_lkey,
-			  &tmp_rkey);
+			  &tmp_rkey, EHCA_REG_MR);
 	if (ret) {
 		u32 offset = (u64)(&e_fmr->flags) - (u64)e_fmr;
 		memcpy(&e_fmr->flags, &(save_mr.flags),
@@ -1478,6 +1524,90 @@ ehca_reg_smr_exit0:
 } /* end ehca_reg_smr() */
 
 /*----------------------------------------------------------------------*/
+static inline void *ehca_calc_sectbase(int top, int dir, int idx)
+{
+	unsigned long ret = idx;
+	ret |= dir << EHCA_DIR_INDEX_SHIFT;
+	ret |= top << EHCA_TOP_INDEX_SHIFT;
+	return abs_to_virt(ret << SECTION_SIZE_BITS);
+}
+
+#define ehca_bmap_valid(entry) \
+	((u64)entry != (u64)EHCA_INVAL_ADDR)
+
+static u64 ehca_reg_mr_section(int top, int dir, int idx, u64 *kpage,
+			       struct ehca_shca *shca, struct ehca_mr *mr,
+			       struct ehca_mr_pginfo *pginfo)
+{
+	u64 h_ret = 0;
+	unsigned long page = 0;
+	u64 rpage = virt_to_abs(kpage);
+	int page_count;
+
+	void *sectbase = ehca_calc_sectbase(top, dir, idx);
+	if ((unsigned long)sectbase & (pginfo->hwpage_size - 1)) {
+		ehca_err(&shca->ib_device, "reg_mr_section will probably fail:"
+					   "hwpage_size does not fit to "
+					   "section start address");
+	}
+	page_count = EHCA_SECTSIZE / pginfo->hwpage_size;
+
+	while (page < page_count) {
+		u64 rnum;
+		for (rnum = 0; (rnum < MAX_RPAGES) && (page < page_count);
+		     rnum++) {
+			void *pg = sectbase + ((page++) * pginfo->hwpage_size);
+			kpage[rnum] = virt_to_abs(pg);
+		}
+
+		h_ret = hipz_h_register_rpage_mr(shca->ipz_hca_handle, mr,
+			ehca_encode_hwpage_size(pginfo->hwpage_size),
+			0, rpage, rnum);
+
+		if ((h_ret != H_SUCCESS) && (h_ret != H_PAGE_REGISTERED)) {
+			ehca_err(&shca->ib_device, "register_rpage_mr failed");
+			return h_ret;
+		}
+	}
+	return h_ret;
+}
+
+static u64 ehca_reg_mr_sections(int top, int dir, u64 *kpage,
+				struct ehca_shca *shca, struct ehca_mr *mr,
+				struct ehca_mr_pginfo *pginfo)
+{
+	u64 hret = H_SUCCESS;
+	int idx;
+
+	for (idx = 0; idx < EHCA_MAP_ENTRIES; idx++) {
+		if (!ehca_bmap_valid(ehca_bmap->top[top]->dir[dir]->ent[idx]))
+			continue;
+
+		hret = ehca_reg_mr_section(top, dir, idx, kpage, shca, mr,
+					   pginfo);
+		if ((hret != H_SUCCESS) && (hret != H_PAGE_REGISTERED))
+				return hret;
+	}
+	return hret;
+}
+
+static u64 ehca_reg_mr_dir_sections(int top, u64 *kpage, struct ehca_shca *shca,
+				    struct ehca_mr *mr,
+				    struct ehca_mr_pginfo *pginfo)
+{
+	u64 hret = H_SUCCESS;
+	int dir;
+
+	for (dir = 0; dir < EHCA_MAP_ENTRIES; dir++) {
+		if (!ehca_bmap_valid(ehca_bmap->top[top]->dir[dir]))
+			continue;
+
+		hret = ehca_reg_mr_sections(top, dir, kpage, shca, mr, pginfo);
+		if ((hret != H_SUCCESS) && (hret != H_PAGE_REGISTERED))
+				return hret;
+	}
+	return hret;
+}
 
 /* register internal max-MR to internal SHCA */
 int ehca_reg_internal_maxmr(
@@ -1495,6 +1625,11 @@ int ehca_reg_internal_maxmr(
 	u32 num_hwpages;
 	u64 hw_pgsize;
 
+	if (!ehca_bmap) {
+		ret = -EFAULT;
+		goto ehca_reg_internal_maxmr_exit0;
+	}
+
 	e_mr = ehca_mr_new();
 	if (!e_mr) {
 		ehca_err(&shca->ib_device, "out of memory");
@@ -1504,8 +1639,8 @@ int ehca_reg_internal_maxmr(
 	e_mr->flags |= EHCA_MR_FLAG_MAXMR;
 
 	/* register internal max-MR on HCA */
-	size_maxmr = (u64)high_memory - PAGE_OFFSET;
-	iova_start = (u64 *)KERNELBASE;
+	size_maxmr = ehca_mr_len;
+	iova_start = (u64 *)ehca_map_vaddr((void *)KERNELBASE);
 	ib_pbuf.addr = 0;
 	ib_pbuf.size = size_maxmr;
 	num_kpages = NUM_CHUNKS(((u64)iova_start % PAGE_SIZE) + size_maxmr,
@@ -1524,7 +1659,7 @@ int ehca_reg_internal_maxmr(
 
 	ret = ehca_reg_mr(shca, e_mr, iova_start, size_maxmr, 0, e_pd,
 			  &pginfo, &e_mr->ib.ib_mr.lkey,
-			  &e_mr->ib.ib_mr.rkey);
+			  &e_mr->ib.ib_mr.rkey, EHCA_REG_BUSMAP_MR);
 	if (ret) {
 		ehca_err(&shca->ib_device, "reg of internal max MR failed, "
 			 "e_mr=%p iova_start=%p size_maxmr=%llx num_kpages=%x "
@@ -2077,8 +2212,8 @@ int ehca_mr_is_maxmr(u64 size,
 		     u64 *iova_start)
 {
 	/* a MR is treated as max-MR only if it fits following: */
-	if ((size == ((u64)high_memory - PAGE_OFFSET)) &&
-	    (iova_start == (void *)KERNELBASE)) {
+	if ((size == ehca_mr_len) &&
+	    (iova_start == (void *)ehca_map_vaddr((void *)KERNELBASE))) {
 		ehca_gen_dbg("this is a max-MR");
 		return 1;
 	} else
@@ -2184,3 +2319,350 @@ void ehca_cleanup_mrmw_cache(void)
 	if (mw_cache)
 		kmem_cache_destroy(mw_cache);
 }
+
+static inline int ehca_init_top_bmap(struct ehca_top_bmap *ehca_top_bmap,
+				     int dir)
+{
+	if (!ehca_bmap_valid(ehca_top_bmap->dir[dir])) {
+		ehca_top_bmap->dir[dir] =
+			kmalloc(sizeof(struct ehca_dir_bmap), GFP_KERNEL);
+		if (!ehca_top_bmap->dir[dir])
+			return -ENOMEM;
+		/* Set map block to 0xFF according to EHCA_INVAL_ADDR */
+		memset(ehca_top_bmap->dir[dir], 0xFF, EHCA_ENT_MAP_SIZE);
+	}
+	return 0;
+}
+
+static inline int ehca_init_bmap(struct ehca_bmap *ehca_bmap, int top, int dir)
+{
+	if (!ehca_bmap_valid(ehca_bmap->top[top])) {
+		ehca_bmap->top[top] =
+			kmalloc(sizeof(struct ehca_top_bmap), GFP_KERNEL);
+		if (!ehca_bmap->top[top])
+			return -ENOMEM;
+		/* Set map block to 0xFF according to EHCA_INVAL_ADDR */
+		memset(ehca_bmap->top[top], 0xFF, EHCA_DIR_MAP_SIZE);
+	}
+	return ehca_init_top_bmap(ehca_bmap->top[top], dir);
+}
+
+static inline int ehca_calc_index(unsigned long i, unsigned long s)
+{
+	return (i >> s) & EHCA_INDEX_MASK;
+}
+
+void ehca_destroy_busmap(void)
+{
+	int top, dir;
+
+	if (!ehca_bmap)
+		return;
+
+	for (top = 0; top < EHCA_MAP_ENTRIES; top++) {
+		if (!ehca_bmap_valid(ehca_bmap->top[top]))
+			continue;
+		for (dir = 0; dir < EHCA_MAP_ENTRIES; dir++) {
+			if (!ehca_bmap_valid(ehca_bmap->top[top]->dir[dir]))
+				continue;
+
+			kfree(ehca_bmap->top[top]->dir[dir]);
+		}
+
+		kfree(ehca_bmap->top[top]);
+	}
+
+	kfree(ehca_bmap);
+	ehca_bmap = NULL;
+}
+
+static int ehca_update_busmap(unsigned long pfn, unsigned long nr_pages)
+{
+	unsigned long i, start_section, end_section;
+	int top, dir, idx;
+
+	if (!nr_pages)
+		return 0;
+
+	if (!ehca_bmap) {
+		ehca_bmap = kmalloc(sizeof(struct ehca_bmap), GFP_KERNEL);
+		if (!ehca_bmap)
+			return -ENOMEM;
+		/* Set map block to 0xFF according to EHCA_INVAL_ADDR */
+		memset(ehca_bmap, 0xFF, EHCA_TOP_MAP_SIZE);
+	}
+
+	start_section = phys_to_abs(pfn * PAGE_SIZE) / EHCA_SECTSIZE;
+	end_section = phys_to_abs((pfn + nr_pages) * PAGE_SIZE) / EHCA_SECTSIZE;
+	for (i = start_section; i < end_section; i++) {
+		int ret;
+		top = ehca_calc_index(i, EHCA_TOP_INDEX_SHIFT);
+		dir = ehca_calc_index(i, EHCA_DIR_INDEX_SHIFT);
+		idx = i & EHCA_INDEX_MASK;
+
+		ret = ehca_init_bmap(ehca_bmap, top, dir);
+		if (ret) {
+			ehca_destroy_busmap();
+			return ret;
+		}
+		ehca_bmap->top[top]->dir[dir]->ent[idx] = ehca_mr_len;
+		ehca_mr_len += EHCA_SECTSIZE;
+	}
+	return 0;
+}
+
+static int ehca_is_hugepage(unsigned long pfn)
+{
+	int page_order;
+
+	if (pfn & EHCA_HUGEPAGE_PFN_MASK)
+		return 0;
+
+	page_order = compound_order(pfn_to_page(pfn));
+	if (page_order + PAGE_SHIFT != EHCA_HUGEPAGESHIFT)
+		return 0;
+
+	return 1;
+}
+
+static int ehca_create_busmap_callback(unsigned long initial_pfn,
+				       unsigned long total_nr_pages, void *arg)
+{
+	int ret;
+	unsigned long pfn, start_pfn, end_pfn, nr_pages;
+
+	if ((total_nr_pages * PAGE_SIZE) < EHCA_HUGEPAGE_SIZE)
+		return ehca_update_busmap(initial_pfn, total_nr_pages);
+
+	/* Given chunk is >= 16GB -> check for hugepages */
+	start_pfn = initial_pfn;
+	end_pfn = initial_pfn + total_nr_pages;
+	pfn = start_pfn;
+
+	while (pfn < end_pfn) {
+		if (ehca_is_hugepage(pfn)) {
+			/* Add mem found in front of the hugepage */
+			nr_pages = pfn - start_pfn;
+			ret = ehca_update_busmap(start_pfn, nr_pages);
+			if (ret)
+				return ret;
+			/* Skip the hugepage */
+			pfn += (EHCA_HUGEPAGE_SIZE / PAGE_SIZE);
+			start_pfn = pfn;
+		} else
+			pfn += (EHCA_SECTSIZE / PAGE_SIZE);
+	}
+
+	/* Add mem found behind the hugepage(s)  */
+	nr_pages = pfn - start_pfn;
+	return ehca_update_busmap(start_pfn, nr_pages);
+}
+
+int ehca_create_busmap(void)
+{
+	int ret;
+
+	ehca_mr_len = 0;
+	ret = walk_memory_resource(0, 1ULL << MAX_PHYSMEM_BITS, NULL,
+				   ehca_create_busmap_callback);
+	return ret;
+}
+
+static int ehca_reg_bmap_mr_rpages(struct ehca_shca *shca,
+				   struct ehca_mr *e_mr,
+				   struct ehca_mr_pginfo *pginfo)
+{
+	int top;
+	u64 hret, *kpage;
+
+	kpage = ehca_alloc_fw_ctrlblock(GFP_KERNEL);
+	if (!kpage) {
+		ehca_err(&shca->ib_device, "kpage alloc failed");
+		return -ENOMEM;
+	}
+	for (top = 0; top < EHCA_MAP_ENTRIES; top++) {
+		if (!ehca_bmap_valid(ehca_bmap->top[top]))
+			continue;
+		hret = ehca_reg_mr_dir_sections(top, kpage, shca, e_mr, pginfo);
+		if ((hret != H_PAGE_REGISTERED) && (hret != H_SUCCESS))
+			break;
+	}
+
+	ehca_free_fw_ctrlblock(kpage);
+
+	if (hret == H_SUCCESS)
+		return 0; /* Everything is fine */
+	else {
+		ehca_err(&shca->ib_device, "ehca_reg_bmap_mr_rpages failed, "
+				 "h_ret=%lli e_mr=%p top=%x lkey=%x "
+				 "hca_hndl=%llx mr_hndl=%llx", hret, e_mr, top,
+				 e_mr->ib.ib_mr.lkey,
+				 shca->ipz_hca_handle.handle,
+				 e_mr->ipz_mr_handle.handle);
+		return ehca2ib_return_code(hret);
+	}
+}
+
+static u64 ehca_map_vaddr(void *caddr)
+{
+	int top, dir, idx;
+	unsigned long abs_addr, offset;
+	u64 entry;
+
+	if (!ehca_bmap)
+		return EHCA_INVAL_ADDR;
+
+	abs_addr = virt_to_abs(caddr);
+	top = ehca_calc_index(abs_addr, EHCA_TOP_INDEX_SHIFT + EHCA_SECTSHIFT);
+	if (!ehca_bmap_valid(ehca_bmap->top[top]))
+		return EHCA_INVAL_ADDR;
+
+	dir = ehca_calc_index(abs_addr, EHCA_DIR_INDEX_SHIFT + EHCA_SECTSHIFT);
+	if (!ehca_bmap_valid(ehca_bmap->top[top]->dir[dir]))
+		return EHCA_INVAL_ADDR;
+
+	idx = ehca_calc_index(abs_addr, EHCA_SECTSHIFT);
+
+	entry = ehca_bmap->top[top]->dir[dir]->ent[idx];
+	if (ehca_bmap_valid(entry)) {
+		offset = (unsigned long)caddr & (EHCA_SECTSIZE - 1);
+		return entry | offset;
+	} else
+		return EHCA_INVAL_ADDR;
+}
+
+static int ehca_dma_mapping_error(struct ib_device *dev, u64 dma_addr)
+{
+	return dma_addr == EHCA_INVAL_ADDR;
+}
+
+static u64 ehca_dma_map_single(struct ib_device *dev, void *cpu_addr,
+			       size_t size, enum dma_data_direction direction)
+{
+	if (cpu_addr)
+		return ehca_map_vaddr(cpu_addr);
+	else
+		return EHCA_INVAL_ADDR;
+}
+
+static void ehca_dma_unmap_single(struct ib_device *dev, u64 addr, size_t size,
+				  enum dma_data_direction direction)
+{
+	/* This is only a stub; nothing to be done here */
+}
+
+static u64 ehca_dma_map_page(struct ib_device *dev, struct page *page,
+			     unsigned long offset, size_t size,
+			     enum dma_data_direction direction)
+{
+	u64 addr;
+
+	if (offset + size > PAGE_SIZE)
+		return EHCA_INVAL_ADDR;
+
+	addr = ehca_map_vaddr(page_address(page));
+	if (!ehca_dma_mapping_error(dev, addr))
+		addr += offset;
+
+	return addr;
+}
+
+static void ehca_dma_unmap_page(struct ib_device *dev, u64 addr, size_t size,
+				enum dma_data_direction direction)
+{
+	/* This is only a stub; nothing to be done here */
+}
+
+static int ehca_dma_map_sg(struct ib_device *dev, struct scatterlist *sgl,
+			   int nents, enum dma_data_direction direction)
+{
+	struct scatterlist *sg;
+	int i;
+
+	for_each_sg(sgl, sg, nents, i) {
+		u64 addr;
+		addr = ehca_map_vaddr(sg_virt(sg));
+		if (ehca_dma_mapping_error(dev, addr))
+			return 0;
+
+		sg->dma_address = addr;
+		sg->dma_length = sg->length;
+	}
+	return nents;
+}
+
+static void ehca_dma_unmap_sg(struct ib_device *dev, struct scatterlist *sg,
+			      int nents, enum dma_data_direction direction)
+{
+	/* This is only a stub; nothing to be done here */
+}
+
+static u64 ehca_dma_address(struct ib_device *dev, struct scatterlist *sg)
+{
+	return sg->dma_address;
+}
+
+static unsigned int ehca_dma_len(struct ib_device *dev, struct scatterlist *sg)
+{
+	return sg->length;
+}
+
+static void ehca_dma_sync_single_for_cpu(struct ib_device *dev, u64 addr,
+					 size_t size,
+					 enum dma_data_direction dir)
+{
+	dma_sync_single_for_cpu(dev->dma_device, addr, size, dir);
+}
+
+static void ehca_dma_sync_single_for_device(struct ib_device *dev, u64 addr,
+					    size_t size,
+					    enum dma_data_direction dir)
+{
+	dma_sync_single_for_device(dev->dma_device, addr, size, dir);
+}
+
+static void *ehca_dma_alloc_coherent(struct ib_device *dev, size_t size,
+				     u64 *dma_handle, gfp_t flag)
+{
+	struct page *p;
+	void *addr = NULL;
+	u64 dma_addr;
+
+	p = alloc_pages(flag, get_order(size));
+	if (p) {
+		addr = page_address(p);
+		dma_addr = ehca_map_vaddr(addr);
+		if (ehca_dma_mapping_error(dev, dma_addr)) {
+			free_pages((unsigned long)addr,	get_order(size));
+			return NULL;
+		}
+		if (dma_handle)
+			*dma_handle = dma_addr;
+		return addr;
+	}
+	return NULL;
+}
+
+static void ehca_dma_free_coherent(struct ib_device *dev, size_t size,
+				   void *cpu_addr, u64 dma_handle)
+{
+	if (cpu_addr && size)
+		free_pages((unsigned long)cpu_addr, get_order(size));
+}
+
+
+struct ib_dma_mapping_ops ehca_dma_mapping_ops = {
+	.mapping_error          = ehca_dma_mapping_error,
+	.map_single             = ehca_dma_map_single,
+	.unmap_single           = ehca_dma_unmap_single,
+	.map_page               = ehca_dma_map_page,
+	.unmap_page             = ehca_dma_unmap_page,
+	.map_sg                 = ehca_dma_map_sg,
+	.unmap_sg               = ehca_dma_unmap_sg,
+	.dma_address            = ehca_dma_address,
+	.dma_len                = ehca_dma_len,
+	.sync_single_for_cpu    = ehca_dma_sync_single_for_cpu,
+	.sync_single_for_device = ehca_dma_sync_single_for_device,
+	.alloc_coherent         = ehca_dma_alloc_coherent,
+	.free_coherent          = ehca_dma_free_coherent,
+};
diff --git a/drivers/infiniband/hw/ehca/ehca_mrmw.h b/drivers/infiniband/hw/ehca/ehca_mrmw.h
index bc8f4e31c123..50d8b51306dd 100644
--- a/drivers/infiniband/hw/ehca/ehca_mrmw.h
+++ b/drivers/infiniband/hw/ehca/ehca_mrmw.h
@@ -42,6 +42,11 @@
 #ifndef _EHCA_MRMW_H_
 #define _EHCA_MRMW_H_
 
+enum ehca_reg_type {
+	EHCA_REG_MR,
+	EHCA_REG_BUSMAP_MR
+};
+
 int ehca_reg_mr(struct ehca_shca *shca,
 		struct ehca_mr *e_mr,
 		u64 *iova_start,
@@ -50,7 +55,8 @@ int ehca_reg_mr(struct ehca_shca *shca,
 		struct ehca_pd *e_pd,
 		struct ehca_mr_pginfo *pginfo,
 		u32 *lkey,
-		u32 *rkey);
+		u32 *rkey,
+		enum ehca_reg_type reg_type);
 
 int ehca_reg_mr_rpages(struct ehca_shca *shca,
 		       struct ehca_mr *e_mr,
@@ -118,4 +124,9 @@ void ehca_mrmw_reverse_map_acl(const u32 *hipz_acl,
 
 void ehca_mr_deletenew(struct ehca_mr *mr);
 
+int ehca_create_busmap(void);
+
+void ehca_destroy_busmap(void);
+
+extern struct ib_dma_mapping_ops ehca_dma_mapping_ops;
 #endif  /*_EHCA_MRMW_H_*/