mlx5_core: Add support for page faults events and low level handling

* Add a handler function pointer in the mlx5_core_qp struct for page
  fault events. Handle page fault events by calling the handler
  function, if not NULL.
* Add on-demand paging capability query command.
* Export command for resuming QPs after page faults.
* Add various constants related to paging support.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Shachar Raindel <raindel@mellanox.com>
Signed-off-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>
diff --git a/include/linux/mlx5/qp.h b/include/linux/mlx5/qp.h
index 67f4b96..6b1d6f6 100644
--- a/include/linux/mlx5/qp.h
+++ b/include/linux/mlx5/qp.h
@@ -50,6 +50,9 @@
 #define MLX5_BSF_APPTAG_ESCAPE	0x1
 #define MLX5_BSF_APPREF_ESCAPE	0x2
 
+#define MLX5_QPN_BITS		24
+#define MLX5_QPN_MASK		((1 << MLX5_QPN_BITS) - 1)
+
 enum mlx5_qp_optpar {
 	MLX5_QP_OPTPAR_ALT_ADDR_PATH		= 1 << 0,
 	MLX5_QP_OPTPAR_RRE			= 1 << 1,
@@ -363,9 +366,46 @@
 	__be16		num_entries;
 };
 
+enum mlx5_pagefault_flags {
+	MLX5_PFAULT_REQUESTOR = 1 << 0,
+	MLX5_PFAULT_WRITE     = 1 << 1,
+	MLX5_PFAULT_RDMA      = 1 << 2,
+};
+
+/* Contains the details of a pagefault. */
+struct mlx5_pagefault {
+	u32			bytes_committed;
+	u8			event_subtype;
+	enum mlx5_pagefault_flags flags;
+	union {
+		/* Initiator or send message responder pagefault details. */
+		struct {
+			/* Received packet size, only valid for responders. */
+			u32	packet_size;
+			/*
+			 * WQE index. Refers to either the send queue or
+			 * receive queue, according to event_subtype.
+			 */
+			u16	wqe_index;
+		} wqe;
+		/* RDMA responder pagefault details */
+		struct {
+			u32	r_key;
+			/*
+			 * Received packet size, minimal size page fault
+			 * resolution required for forward progress.
+			 */
+			u32	packet_size;
+			u32	rdma_op_len;
+			u64	rdma_va;
+		} rdma;
+	};
+};
+
 struct mlx5_core_qp {
 	struct mlx5_core_rsc_common	common; /* must be first */
 	void (*event)		(struct mlx5_core_qp *, int);
+	void (*pfault_handler)(struct mlx5_core_qp *, struct mlx5_pagefault *);
 	int			qpn;
 	struct mlx5_rsc_debug	*dbg;
 	int			pid;
@@ -533,6 +573,17 @@
 	return radix_tree_lookup(&dev->priv.mr_table.tree, key);
 }
 
+struct mlx5_page_fault_resume_mbox_in {
+	struct mlx5_inbox_hdr	hdr;
+	__be32			flags_qpn;
+	u8			reserved[4];
+};
+
+struct mlx5_page_fault_resume_mbox_out {
+	struct mlx5_outbox_hdr	hdr;
+	u8			rsvd[8];
+};
+
 int mlx5_core_create_qp(struct mlx5_core_dev *dev,
 			struct mlx5_core_qp *qp,
 			struct mlx5_create_qp_mbox_in *in,
@@ -552,6 +603,10 @@
 void mlx5_cleanup_qp_table(struct mlx5_core_dev *dev);
 int mlx5_debug_qp_add(struct mlx5_core_dev *dev, struct mlx5_core_qp *qp);
 void mlx5_debug_qp_remove(struct mlx5_core_dev *dev, struct mlx5_core_qp *qp);
+#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
+int mlx5_core_page_fault_resume(struct mlx5_core_dev *dev, u32 qpn,
+				u8 context, int error);
+#endif
 
 static inline const char *mlx5_qp_type_str(int type)
 {