RDMA: During rereg_mr ensure that REREG_ACCESS is compatible

If IB_MR_REREG_ACCESS changes from RO to RW then the umem has to be
re-evaluated to ensure it is properly pinned as RW. Since the umem is
hidden inside each driver's mr struct add a ib_umem_check_rereg() function
that each driver has to call before processing IB_MR_REREG_ACCESS.

mlx4 has to retain its duplicate ib_access_writable check because it
implements IB_MR_REREG_ACCESS | IB_MR_REREG_TRANS by changing both items
in place sequentially while the MR is live, so it will continue to not
support this combination.

Cc: stable@vger.kernel.org
Fixes: b40656aa7d ("RDMA/umem: remove FOLL_FORCE usage")
Link: https://patch.msgid.link/r/0-v1-06fb1a2d6cf5+107-rereg_access_jgg@nvidia.com
Reported-by: Philip Tsukerman <philiptsukerman@gmail.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/umem.c

@@ -332,3 +332,19 @@ int ib_umem_copy_from(void *dst, struct ib_umem *umem, size_t offset,
 		return 0;
 }
 EXPORT_SYMBOL(ib_umem_copy_from);
+
+/*
+ * Called during rereg mr if the driver is able to re-use a umem for
+ * IB_MR_REREG_ACCESS.
+ */
+int ib_umem_check_rereg(struct ib_umem *umem, int flags, int new_access_flags)
+{
+	if (!umem)
+		return 0;
+
+	if ((flags & IB_MR_REREG_ACCESS) && !(flags & IB_MR_REREG_TRANS))
+		if (ib_access_writable(new_access_flags) && !umem->writable)
+			return -EACCES;
+	return 0;
+}
+EXPORT_SYMBOL(ib_umem_check_rereg);

drivers/infiniband/hw/hns/hns_roce_mr.c

@@ -300,6 +300,10 @@ struct ib_mr *hns_roce_rereg_user_mr(struct ib_mr *ibmr, int flags, u64 start,
 		goto err_out;
 	}
 
+	ret = ib_umem_check_rereg(mr->pbl_mtr.umem, flags, mr_access_flags);
+	if (ret)
+		goto err_out;
+
 	mailbox = hns_roce_alloc_cmd_mailbox(hr_dev);
 	ret = PTR_ERR_OR_ZERO(mailbox);
 	if (ret)

drivers/infiniband/hw/irdma/verbs.c

@@ -3803,6 +3803,10 @@ static struct ib_mr *irdma_rereg_user_mr(struct ib_mr *ib_mr, int flags,
 	if (flags & ~(IB_MR_REREG_TRANS | IB_MR_REREG_PD | IB_MR_REREG_ACCESS))
 		return ERR_PTR(-EOPNOTSUPP);
 
+	ret = ib_umem_check_rereg(iwmr->region, flags, new_access);
+	if (ret)
+		return ERR_PTR(ret);
+
 	if (dmabuf_revocable) {
 		umem_dmabuf = to_ib_umem_dmabuf(iwmr->region);
 

drivers/infiniband/hw/mlx4/mr.c

@@ -209,6 +209,10 @@ struct ib_mr *mlx4_ib_rereg_user_mr(struct ib_mr *mr, int flags, u64 start,
 	struct mlx4_mpt_entry **pmpt_entry = &mpt_entry;
 	int err;
 
+	err = ib_umem_check_rereg(mmr->umem, flags, mr_access_flags);
+	if (err)
+		return ERR_PTR(err);
+
 	/* Since we synchronize this call and mlx4_ib_dereg_mr via uverbs,
 	 * we assume that the calls can't run concurrently. Otherwise, a
 	 * race exists.

drivers/infiniband/hw/mlx5/mr.c

@@ -1179,6 +1179,10 @@ struct ib_mr *mlx5_ib_rereg_user_mr(struct ib_mr *ib_mr, int flags, u64 start,
 	if (flags & ~(IB_MR_REREG_TRANS | IB_MR_REREG_PD | IB_MR_REREG_ACCESS))
 		return ERR_PTR(-EOPNOTSUPP);
 
+	err = ib_umem_check_rereg(mr->umem, flags, new_access_flags);
+	if (err)
+		return ERR_PTR(err);
+
 	if (!(flags & IB_MR_REREG_ACCESS))
 		new_access_flags = mr->access_flags;
 	if (!(flags & IB_MR_REREG_PD))

drivers/infiniband/sw/rxe/rxe_verbs.c

@@ -1319,6 +1319,7 @@ static struct ib_mr *rxe_rereg_user_mr(struct ib_mr *ibmr, int flags,
 	struct rxe_mr *mr = to_rmr(ibmr);
 	struct rxe_pd *old_pd = to_rpd(ibmr->pd);
 	struct rxe_pd *pd = to_rpd(ibpd);
+	int err;
 
 	/* for now only support the two easy cases:
 	 * rereg_pd and rereg_access
@@ -1328,6 +1329,10 @@ static struct ib_mr *rxe_rereg_user_mr(struct ib_mr *ibmr, int flags,
 		return ERR_PTR(-EOPNOTSUPP);
 	}
 
+	err = ib_umem_check_rereg(mr->umem, flags, access);
+	if (err)
+		return ERR_PTR(err);
+
 	if (flags & IB_MR_REREG_PD) {
 		rxe_put(old_pd);
 		rxe_get(pd);

include/rdma/ib_umem.h

@@ -156,6 +156,8 @@ void ib_umem_dmabuf_revoke_lock(struct ib_umem_dmabuf *umem_dmabuf);
 void ib_umem_dmabuf_revoke_unlock(struct ib_umem_dmabuf *umem_dmabuf);
 void ib_umem_dmabuf_revoke(struct ib_umem_dmabuf *umem_dmabuf);
 
+int ib_umem_check_rereg(struct ib_umem *umem, int flags, int new_access_flags);
+
 #else /* CONFIG_INFINIBAND_USER_MEM */
 
 #include <linux/err.h>
@@ -230,5 +232,11 @@ static inline void ib_umem_dmabuf_revoke_lock(struct ib_umem_dmabuf *umem_dmabuf
 static inline void ib_umem_dmabuf_revoke_unlock(struct ib_umem_dmabuf *umem_dmabuf) {}
 static inline void ib_umem_dmabuf_revoke(struct ib_umem_dmabuf *umem_dmabuf) {}
 
+static inline int ib_umem_check_rereg(struct ib_umem *umem, int flags,
+				      int new_access_flags)
+{
+	return -EOPNOTSUPP;
+}
+
 #endif /* CONFIG_INFINIBAND_USER_MEM */
 #endif /* IB_UMEM_H */