RDMA/rxe: Add ib_alloc_mw and ib_dealloc_mw verbs

Add ib_alloc_mw and ib_dealloc_mw verbs APIs.

Added new file rxe_mw.c focused on MWs. Changed the 8 bit random key
generator. Added a cleanup routine for MWs. Added verbs routines to
ib_device_ops.

Link: https://lore.kernel.org/r/20210608042552.33275-5-rpearsonhpe@gmail.com
Signed-off-by: Bob Pearson <rpearsonhpe@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/sw/rxe/Makefile

@@ -15,6 +15,7 @@ rdma_rxe-y := \
 	rxe_qp.o \
 	rxe_cq.o \
 	rxe_mr.o \
+	rxe_mw.o \
 	rxe_opcode.o \
 	rxe_mmap.o \
 	rxe_icrc.o \

drivers/infiniband/sw/rxe/rxe_loc.h

@@ -76,6 +76,7 @@ enum copy_direction {
 	from_mr_obj,
 };
 
+u8 rxe_get_next_key(u32 last_key);
 void rxe_mr_init_dma(struct rxe_pd *pd, int access, struct rxe_mr *mr);
 
 int rxe_mr_init_user(struct rxe_pd *pd, u64 start, u64 length, u64 iova,
@@ -106,6 +107,11 @@ void rxe_mr_cleanup(struct rxe_pool_entry *arg);
 
 int advance_dma_data(struct rxe_dma_info *dma, unsigned int length);
 
+/* rxe_mw.c */
+int rxe_alloc_mw(struct ib_mw *ibmw, struct ib_udata *udata);
+int rxe_dealloc_mw(struct ib_mw *ibmw);
+void rxe_mw_cleanup(struct rxe_pool_entry *arg);
+
 /* rxe_net.c */
 void rxe_loopback(struct sk_buff *skb);
 int rxe_send(struct rxe_pkt_info *pkt, struct sk_buff *skb);

drivers/infiniband/sw/rxe/rxe_mr.c

@@ -7,19 +7,17 @@
 #include "rxe.h"
 #include "rxe_loc.h"
 
-/*
- * lfsr (linear feedback shift register) with period 255
+/* Return a random 8 bit key value that is
+ * different than the last_key. Set last_key to -1
+ * if this is the first key for an MR or MW
  */
-static u8 rxe_get_key(void)
+u8 rxe_get_next_key(u32 last_key)
 {
-	static u32 key = 1;
+	u8 key;
 
-	key = key << 1;
-
-	key |= (0 != (key & 0x100)) ^ (0 != (key & 0x10))
-		^ (0 != (key & 0x80)) ^ (0 != (key & 0x40));
-
-	key &= 0xff;
+	do {
+		get_random_bytes(&key, 1);
+	} while (key == last_key);
 
 	return key;
 }
@@ -47,7 +45,7 @@ int mr_check_range(struct rxe_mr *mr, u64 iova, size_t length)
 
 static void rxe_mr_init(int access, struct rxe_mr *mr)
 {
-	u32 lkey = mr->pelem.index << 8 | rxe_get_key();
+	u32 lkey = mr->pelem.index << 8 | rxe_get_next_key(-1);
 	u32 rkey = (access & IB_ACCESS_REMOTE) ? lkey : 0;
 
 	mr->ibmr.lkey = lkey;

drivers/infiniband/sw/rxe/rxe_mw.c

@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0 OR Linux-OpenIB
+/*
+ * Copyright (c) 2020 Hewlett Packard Enterprise, Inc. All rights reserved.
+ */
+
+#include "rxe.h"
+
+int rxe_alloc_mw(struct ib_mw *ibmw, struct ib_udata *udata)
+{
+	struct rxe_mw *mw = to_rmw(ibmw);
+	struct rxe_pd *pd = to_rpd(ibmw->pd);
+	struct rxe_dev *rxe = to_rdev(ibmw->device);
+	int ret;
+
+	rxe_add_ref(pd);
+
+	ret = rxe_add_to_pool(&rxe->mw_pool, mw);
+	if (ret) {
+		rxe_drop_ref(pd);
+		return ret;
+	}
+
+	rxe_add_index(mw);
+	ibmw->rkey = (mw->pelem.index << 8) | rxe_get_next_key(-1);
+	mw->state = (mw->ibmw.type == IB_MW_TYPE_2) ?
+			RXE_MW_STATE_FREE : RXE_MW_STATE_VALID;
+	spin_lock_init(&mw->lock);
+
+	return 0;
+}
+
+int rxe_dealloc_mw(struct ib_mw *ibmw)
+{
+	struct rxe_mw *mw = to_rmw(ibmw);
+	struct rxe_pd *pd = to_rpd(ibmw->pd);
+	unsigned long flags;
+
+	spin_lock_irqsave(&mw->lock, flags);
+	mw->state = RXE_MW_STATE_INVALID;
+	spin_unlock_irqrestore(&mw->lock, flags);
+
+	rxe_drop_ref(mw);
+	rxe_drop_ref(pd);
+
+	return 0;
+}
+
+void rxe_mw_cleanup(struct rxe_pool_entry *elem)
+{
+	struct rxe_mw *mw = container_of(elem, typeof(*mw), pelem);
+
+	rxe_drop_index(mw);
+}

drivers/infiniband/sw/rxe/rxe_pool.c

@@ -65,6 +65,7 @@ struct rxe_type_info rxe_type_info[RXE_NUM_TYPES] = {
 		.name		= "rxe-mw",
 		.size		= sizeof(struct rxe_mw),
 		.elem_offset	= offsetof(struct rxe_mw, pelem),
+		.cleanup	= rxe_mw_cleanup,
 		.flags		= RXE_POOL_INDEX | RXE_POOL_NO_ALLOC,
 		.max_index	= RXE_MAX_MW_INDEX,
 		.min_index	= RXE_MIN_MW_INDEX,

drivers/infiniband/sw/rxe/rxe_verbs.c

@@ -1106,6 +1106,7 @@ static const struct ib_device_ops rxe_dev_ops = {
 
 	.alloc_hw_stats = rxe_ib_alloc_hw_stats,
 	.alloc_mr = rxe_alloc_mr,
+	.alloc_mw = rxe_alloc_mw,
 	.alloc_pd = rxe_alloc_pd,
 	.alloc_ucontext = rxe_alloc_ucontext,
 	.attach_mcast = rxe_attach_mcast,
@@ -1115,6 +1116,7 @@ static const struct ib_device_ops rxe_dev_ops = {
 	.create_srq = rxe_create_srq,
 	.create_user_ah = rxe_create_ah,
 	.dealloc_driver = rxe_dealloc,
+	.dealloc_mw = rxe_dealloc_mw,
 	.dealloc_pd = rxe_dealloc_pd,
 	.dealloc_ucontext = rxe_dealloc_ucontext,
 	.dereg_mr = rxe_dereg_mr,

drivers/infiniband/sw/rxe/rxe_verbs.h

@@ -326,6 +326,8 @@ enum rxe_mw_state {
 struct rxe_mw {
 	struct ib_mw ibmw;
 	struct rxe_pool_entry pelem;
+	spinlock_t lock;
+	enum rxe_mw_state state;
 };
 
 struct rxe_mc_grp {