RDMA/rxe: Break endless pagefault loop for RO pages

RO pages has "perm" equal to 0, that caused to the situation
where such pages were marked as needed to have fault and caused
to infinite loop.

Fixes: eedd5b1 ("RDMA/umem: Store ODP access mask information in PFN")
Reported-by: Daisuke Matsuda <dskmtsd@gmail.com>
Closes: https://lore.kernel.org/all/3016329a-4edd-4550-862f-b298a1b79a39@gmail.com/
Link: https://patch.msgid.link/096fab178d48ed86942ee22eafe9be98e29092aa.1747913377.git.leonro@nvidia.com
Tested-by: Daisuke Matsuda <dskmtsd@gmail.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>

Author: rleon

drivers/infiniband/sw/rxe/rxe_odp.c

@@ -124,8 +124,8 @@ int rxe_odp_mr_init_user(struct rxe_dev *rxe, u64 start, u64 length,
 	return err;
 }
 
-static inline bool rxe_check_pagefault(struct ib_umem_odp *umem_odp,
-				       u64 iova, int length, u32 perm)
+static inline bool rxe_check_pagefault(struct ib_umem_odp *umem_odp, u64 iova,
+				       int length)
 {
 	bool need_fault = false;
 	u64 addr;
@@ -137,7 +137,7 @@ static inline bool rxe_check_pagefault(struct ib_umem_odp *umem_odp,
 	while (addr < iova + length) {
 		idx = (addr - ib_umem_start(umem_odp)) >> umem_odp->page_shift;
 
-		if (!(umem_odp->map.pfn_list[idx] & perm)) {
+		if (!(umem_odp->map.pfn_list[idx] & HMM_PFN_VALID)) {
 			need_fault = true;
 			break;
 		}
@@ -161,18 +161,14 @@ static int rxe_odp_map_range_and_lock(struct rxe_mr *mr, u64 iova, int length, u
 {
 	struct ib_umem_odp *umem_odp = to_ib_umem_odp(mr->umem);
 	bool need_fault;
-	u64 perm = 0;
 	int err;
 
 	if (unlikely(length < 1))
 		return -EINVAL;
 
-	if (!(flags & RXE_PAGEFAULT_RDONLY))
-		perm |= HMM_PFN_WRITE;
-
 	mutex_lock(&umem_odp->umem_mutex);
 
-	need_fault = rxe_check_pagefault(umem_odp, iova, length, perm);
+	need_fault = rxe_check_pagefault(umem_odp, iova, length);
 	if (need_fault) {
 		mutex_unlock(&umem_odp->umem_mutex);
 
@@ -182,7 +178,7 @@ static int rxe_odp_map_range_and_lock(struct rxe_mr *mr, u64 iova, int length, u
 		if (err < 0)
 			return err;
 
-		need_fault = rxe_check_pagefault(umem_odp, iova, length, perm);
+		need_fault = rxe_check_pagefault(umem_odp, iova, length);
 		if (need_fault)
 			return -EFAULT;
 	}