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Commit 7bdf65d4 authored by Haggai Eran's avatar Haggai Eran Committed by Roland Dreier
Browse files

IB/mlx5: Handle page faults 



This patch implement a page fault handler (leaving the pages pinned as
of time being).  The page fault handler handles initiator and responder
page faults for UD/RC transports, for send/receive operations, as well
as RDMA read/write initiator support.

Signed-off-by: default avatarSagi Grimberg <sagig@mellanox.com>
Signed-off-by: default avatarShachar Raindel <raindel@mellanox.com>
Signed-off-by: default avatarHaggai Eran <haggaie@mellanox.com>
Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
parent 6aec21f6

drivers/infiniband/hw/mlx5/odp.c

+408 −0
Original line number Diff line number Diff line
@@ -30,6 +30,9 @@ 
 * SOFTWARE.

 */



#include <rdma/ib_umem.h>

#include <rdma/ib_umem_odp.h>



#include "mlx5_ib.h"



struct workqueue_struct *mlx5_ib_page_fault_wq;
@@ -85,12 +88,417 @@ static void mlx5_ib_page_fault_resume(struct mlx5_ib_qp *qp, 
		       qp->mqp.qpn);

}



/*

 * Handle a single data segment in a page-fault WQE.

 *

 * Returns number of pages retrieved on success. The caller will continue to

 * the next data segment.

 * Can return the following error codes:

 * -EAGAIN to designate a temporary error. The caller will abort handling the

 *  page fault and resolve it.

 * -EFAULT when there's an error mapping the requested pages. The caller will

 *  abort the page fault handling and possibly move the QP to an error state.

 * On other errors the QP should also be closed with an error.

 */

static int pagefault_single_data_segment(struct mlx5_ib_qp *qp,

					 struct mlx5_ib_pfault *pfault,

					 u32 key, u64 io_virt, size_t bcnt,

					 u32 *bytes_mapped)

{

	struct mlx5_ib_dev *mib_dev = to_mdev(qp->ibqp.pd->device);

	int srcu_key;

	unsigned int current_seq;

	u64 start_idx;

	int npages = 0, ret = 0;

	struct mlx5_ib_mr *mr;

	u64 access_mask = ODP_READ_ALLOWED_BIT;



	srcu_key = srcu_read_lock(&mib_dev->mr_srcu);

	mr = mlx5_ib_odp_find_mr_lkey(mib_dev, key);

	/*

	 * If we didn't find the MR, it means the MR was closed while we were

	 * handling the ODP event. In this case we return -EFAULT so that the

	 * QP will be closed.

	 */

	if (!mr || !mr->ibmr.pd) {

		pr_err("Failed to find relevant mr for lkey=0x%06x, probably the MR was destroyed\n",

		       key);

		ret = -EFAULT;

		goto srcu_unlock;

	}

	if (!mr->umem->odp_data) {

		pr_debug("skipping non ODP MR (lkey=0x%06x) in page fault handler.\n",

			 key);

		if (bytes_mapped)

			*bytes_mapped +=

				(bcnt - pfault->mpfault.bytes_committed);

		goto srcu_unlock;

	}

	if (mr->ibmr.pd != qp->ibqp.pd) {

		pr_err("Page-fault with different PDs for QP and MR.\n");

		ret = -EFAULT;

		goto srcu_unlock;

	}



	current_seq = ACCESS_ONCE(mr->umem->odp_data->notifiers_seq);



	/*

	 * Avoid branches - this code will perform correctly

	 * in all iterations (in iteration 2 and above,

	 * bytes_committed == 0).

	 */

	io_virt += pfault->mpfault.bytes_committed;

	bcnt -= pfault->mpfault.bytes_committed;



	start_idx = (io_virt - (mr->mmr.iova & PAGE_MASK)) >> PAGE_SHIFT;



	if (mr->umem->writable)

		access_mask |= ODP_WRITE_ALLOWED_BIT;

	npages = ib_umem_odp_map_dma_pages(mr->umem, io_virt, bcnt,

					   access_mask, current_seq);

	if (npages < 0) {

		ret = npages;

		goto srcu_unlock;

	}



	if (npages > 0) {

		mutex_lock(&mr->umem->odp_data->umem_mutex);

		/*

		 * No need to check whether the MTTs really belong to

		 * this MR, since ib_umem_odp_map_dma_pages already

		 * checks this.

		 */

		ret = mlx5_ib_update_mtt(mr, start_idx, npages, 0);

		mutex_unlock(&mr->umem->odp_data->umem_mutex);

		if (ret < 0) {

			pr_err("Failed to update mkey page tables\n");

			goto srcu_unlock;

		}



		if (bytes_mapped) {

			u32 new_mappings = npages * PAGE_SIZE -

				(io_virt - round_down(io_virt, PAGE_SIZE));

			*bytes_mapped += min_t(u32, new_mappings, bcnt);

		}

	}



srcu_unlock:

	srcu_read_unlock(&mib_dev->mr_srcu, srcu_key);

	pfault->mpfault.bytes_committed = 0;

	return ret ? ret : npages;

}



/**

 * Parse a series of data segments for page fault handling.

 *

 * @qp the QP on which the fault occurred.

 * @pfault contains page fault information.

 * @wqe points at the first data segment in the WQE.

 * @wqe_end points after the end of the WQE.

 * @bytes_mapped receives the number of bytes that the function was able to

 *               map. This allows the caller to decide intelligently whether

 *               enough memory was mapped to resolve the page fault

 *               successfully (e.g. enough for the next MTU, or the entire

 *               WQE).

 * @total_wqe_bytes receives the total data size of this WQE in bytes (minus

 *                  the committed bytes).

 *

 * Returns the number of pages loaded if positive, zero for an empty WQE, or a

 * negative error code.

 */

static int pagefault_data_segments(struct mlx5_ib_qp *qp,

				   struct mlx5_ib_pfault *pfault, void *wqe,

				   void *wqe_end, u32 *bytes_mapped,

				   u32 *total_wqe_bytes, int receive_queue)

{

	int ret = 0, npages = 0;

	u64 io_virt;

	u32 key;

	u32 byte_count;

	size_t bcnt;

	int inline_segment;



	/* Skip SRQ next-WQE segment. */

	if (receive_queue && qp->ibqp.srq)

		wqe += sizeof(struct mlx5_wqe_srq_next_seg);



	if (bytes_mapped)

		*bytes_mapped = 0;

	if (total_wqe_bytes)

		*total_wqe_bytes = 0;



	while (wqe < wqe_end) {

		struct mlx5_wqe_data_seg *dseg = wqe;



		io_virt = be64_to_cpu(dseg->addr);

		key = be32_to_cpu(dseg->lkey);

		byte_count = be32_to_cpu(dseg->byte_count);

		inline_segment = !!(byte_count &  MLX5_INLINE_SEG);

		bcnt	       = byte_count & ~MLX5_INLINE_SEG;



		if (inline_segment) {

			bcnt = bcnt & MLX5_WQE_INLINE_SEG_BYTE_COUNT_MASK;

			wqe += ALIGN(sizeof(struct mlx5_wqe_inline_seg) + bcnt,

				     16);

		} else {

			wqe += sizeof(*dseg);

		}



		/* receive WQE end of sg list. */

		if (receive_queue && bcnt == 0 && key == MLX5_INVALID_LKEY &&

		    io_virt == 0)

			break;



		if (!inline_segment && total_wqe_bytes) {

			*total_wqe_bytes += bcnt - min_t(size_t, bcnt,

					pfault->mpfault.bytes_committed);

		}



		/* A zero length data segment designates a length of 2GB. */

		if (bcnt == 0)

			bcnt = 1U << 31;



		if (inline_segment || bcnt <= pfault->mpfault.bytes_committed) {

			pfault->mpfault.bytes_committed -=

				min_t(size_t, bcnt,

				      pfault->mpfault.bytes_committed);

			continue;

		}



		ret = pagefault_single_data_segment(qp, pfault, key, io_virt,

						    bcnt, bytes_mapped);

		if (ret < 0)

			break;

		npages += ret;

	}



	return ret < 0 ? ret : npages;

}



/*

 * Parse initiator WQE. Advances the wqe pointer to point at the

 * scatter-gather list, and set wqe_end to the end of the WQE.

 */

static int mlx5_ib_mr_initiator_pfault_handler(

	struct mlx5_ib_qp *qp, struct mlx5_ib_pfault *pfault,

	void **wqe, void **wqe_end, int wqe_length)

{

	struct mlx5_ib_dev *dev = to_mdev(qp->ibqp.pd->device);

	struct mlx5_wqe_ctrl_seg *ctrl = *wqe;

	u16 wqe_index = pfault->mpfault.wqe.wqe_index;

	unsigned ds, opcode;

#if defined(DEBUG)

	u32 ctrl_wqe_index, ctrl_qpn;

#endif



	ds = be32_to_cpu(ctrl->qpn_ds) & MLX5_WQE_CTRL_DS_MASK;

	if (ds * MLX5_WQE_DS_UNITS > wqe_length) {

		mlx5_ib_err(dev, "Unable to read the complete WQE. ds = 0x%x, ret = 0x%x\n",

			    ds, wqe_length);

		return -EFAULT;

	}



	if (ds == 0) {

		mlx5_ib_err(dev, "Got WQE with zero DS. wqe_index=%x, qpn=%x\n",

			    wqe_index, qp->mqp.qpn);

		return -EFAULT;

	}



#if defined(DEBUG)

	ctrl_wqe_index = (be32_to_cpu(ctrl->opmod_idx_opcode) &

			MLX5_WQE_CTRL_WQE_INDEX_MASK) >>

			MLX5_WQE_CTRL_WQE_INDEX_SHIFT;

	if (wqe_index != ctrl_wqe_index) {

		mlx5_ib_err(dev, "Got WQE with invalid wqe_index. wqe_index=0x%x, qpn=0x%x ctrl->wqe_index=0x%x\n",

			    wqe_index, qp->mqp.qpn,

			    ctrl_wqe_index);

		return -EFAULT;

	}



	ctrl_qpn = (be32_to_cpu(ctrl->qpn_ds) & MLX5_WQE_CTRL_QPN_MASK) >>

		MLX5_WQE_CTRL_QPN_SHIFT;

	if (qp->mqp.qpn != ctrl_qpn) {

		mlx5_ib_err(dev, "Got WQE with incorrect QP number. wqe_index=0x%x, qpn=0x%x ctrl->qpn=0x%x\n",

			    wqe_index, qp->mqp.qpn,

			    ctrl_qpn);

		return -EFAULT;

	}

#endif /* DEBUG */



	*wqe_end = *wqe + ds * MLX5_WQE_DS_UNITS;

	*wqe += sizeof(*ctrl);



	opcode = be32_to_cpu(ctrl->opmod_idx_opcode) &

		 MLX5_WQE_CTRL_OPCODE_MASK;

	switch (qp->ibqp.qp_type) {

	case IB_QPT_RC:

		switch (opcode) {

		case MLX5_OPCODE_SEND:

		case MLX5_OPCODE_SEND_IMM:

		case MLX5_OPCODE_SEND_INVAL:

			if (!(dev->odp_caps.per_transport_caps.rc_odp_caps &

			      IB_ODP_SUPPORT_SEND))

				goto invalid_transport_or_opcode;

			break;

		case MLX5_OPCODE_RDMA_WRITE:

		case MLX5_OPCODE_RDMA_WRITE_IMM:

			if (!(dev->odp_caps.per_transport_caps.rc_odp_caps &

			      IB_ODP_SUPPORT_WRITE))

				goto invalid_transport_or_opcode;

			*wqe += sizeof(struct mlx5_wqe_raddr_seg);

			break;

		case MLX5_OPCODE_RDMA_READ:

			if (!(dev->odp_caps.per_transport_caps.rc_odp_caps &

			      IB_ODP_SUPPORT_READ))

				goto invalid_transport_or_opcode;

			*wqe += sizeof(struct mlx5_wqe_raddr_seg);

			break;

		default:

			goto invalid_transport_or_opcode;

		}

		break;

	case IB_QPT_UD:

		switch (opcode) {

		case MLX5_OPCODE_SEND:

		case MLX5_OPCODE_SEND_IMM:

			if (!(dev->odp_caps.per_transport_caps.ud_odp_caps &

			      IB_ODP_SUPPORT_SEND))

				goto invalid_transport_or_opcode;

			*wqe += sizeof(struct mlx5_wqe_datagram_seg);

			break;

		default:

			goto invalid_transport_or_opcode;

		}

		break;

	default:

invalid_transport_or_opcode:

		mlx5_ib_err(dev, "ODP fault on QP of an unsupported opcode or transport. transport: 0x%x opcode: 0x%x.\n",

			    qp->ibqp.qp_type, opcode);

		return -EFAULT;

	}



	return 0;

}



/*

 * Parse responder WQE. Advances the wqe pointer to point at the

 * scatter-gather list, and set wqe_end to the end of the WQE.

 */

static int mlx5_ib_mr_responder_pfault_handler(

	struct mlx5_ib_qp *qp, struct mlx5_ib_pfault *pfault,

	void **wqe, void **wqe_end, int wqe_length)

{

	struct mlx5_ib_dev *dev = to_mdev(qp->ibqp.pd->device);

	struct mlx5_ib_wq *wq = &qp->rq;

	int wqe_size = 1 << wq->wqe_shift;



	if (qp->ibqp.srq) {

		mlx5_ib_err(dev, "ODP fault on SRQ is not supported\n");

		return -EFAULT;

	}



	if (qp->wq_sig) {

		mlx5_ib_err(dev, "ODP fault with WQE signatures is not supported\n");

		return -EFAULT;

	}



	if (wqe_size > wqe_length) {

		mlx5_ib_err(dev, "Couldn't read all of the receive WQE's content\n");

		return -EFAULT;

	}



	switch (qp->ibqp.qp_type) {

	case IB_QPT_RC:

		if (!(dev->odp_caps.per_transport_caps.rc_odp_caps &

		      IB_ODP_SUPPORT_RECV))

			goto invalid_transport_or_opcode;

		break;

	default:

invalid_transport_or_opcode:

		mlx5_ib_err(dev, "ODP fault on QP of an unsupported transport. transport: 0x%x\n",

			    qp->ibqp.qp_type);

		return -EFAULT;

	}



	*wqe_end = *wqe + wqe_size;



	return 0;

}



static void mlx5_ib_mr_wqe_pfault_handler(struct mlx5_ib_qp *qp,

					  struct mlx5_ib_pfault *pfault)

{

	struct mlx5_ib_dev *dev = to_mdev(qp->ibqp.pd->device);

	int ret;

	void *wqe, *wqe_end;

	u32 bytes_mapped, total_wqe_bytes;

	char *buffer = NULL;

	int resume_with_error = 0;

	u16 wqe_index = pfault->mpfault.wqe.wqe_index;

	int requestor = pfault->mpfault.flags & MLX5_PFAULT_REQUESTOR;



	buffer = (char *)__get_free_page(GFP_KERNEL);

	if (!buffer) {

		mlx5_ib_err(dev, "Error allocating memory for IO page fault handling.\n");

		resume_with_error = 1;

		goto resolve_page_fault;

	}



	ret = mlx5_ib_read_user_wqe(qp, requestor, wqe_index, buffer,

				    PAGE_SIZE);

	if (ret < 0) {

		mlx5_ib_err(dev, "Failed reading a WQE following page fault, error=%x, wqe_index=%x, qpn=%x\n",

			    -ret, wqe_index, qp->mqp.qpn);

		resume_with_error = 1;

		goto resolve_page_fault;

	}



	wqe = buffer;

	if (requestor)

		ret = mlx5_ib_mr_initiator_pfault_handler(qp, pfault, &wqe,

							  &wqe_end, ret);

	else

		ret = mlx5_ib_mr_responder_pfault_handler(qp, pfault, &wqe,

							  &wqe_end, ret);

	if (ret < 0) {

		resume_with_error = 1;

		goto resolve_page_fault;

	}



	if (wqe >= wqe_end) {

		mlx5_ib_err(dev, "ODP fault on invalid WQE.\n");

		resume_with_error = 1;

		goto resolve_page_fault;

	}



	ret = pagefault_data_segments(qp, pfault, wqe, wqe_end, &bytes_mapped,

				      &total_wqe_bytes, !requestor);

	if (ret == -EAGAIN) {

		goto resolve_page_fault;

	} else if (ret < 0 || total_wqe_bytes > bytes_mapped) {

		mlx5_ib_err(dev, "Error getting user pages for page fault. Error: 0x%x\n",

			    -ret);

		resume_with_error = 1;

		goto resolve_page_fault;

	}



resolve_page_fault:

	mlx5_ib_page_fault_resume(qp, pfault, resume_with_error);

	mlx5_ib_dbg(dev, "PAGE FAULT completed. QP 0x%x resume_with_error=%d, flags: 0x%x\n",

		    qp->mqp.qpn, resume_with_error, pfault->mpfault.flags);



	free_page((unsigned long)buffer);

}



void mlx5_ib_mr_pfault_handler(struct mlx5_ib_qp *qp,

			       struct mlx5_ib_pfault *pfault)

{

	u8 event_subtype = pfault->mpfault.event_subtype;



	switch (event_subtype) {

	case MLX5_PFAULT_SUBTYPE_WQE:

		mlx5_ib_mr_wqe_pfault_handler(qp, pfault);

		break;

	default:

		pr_warn("Invalid page fault event subtype: 0x%x\n",

			event_subtype);

include/linux/mlx5/qp.h

+7 −0
Original line number Diff line number Diff line
@@ -193,7 +193,12 @@ struct mlx5_wqe_ctrl_seg { 
};



#define MLX5_WQE_CTRL_DS_MASK 0x3f

#define MLX5_WQE_CTRL_QPN_MASK 0xffffff00

#define MLX5_WQE_CTRL_QPN_SHIFT 8

#define MLX5_WQE_DS_UNITS 16

#define MLX5_WQE_CTRL_OPCODE_MASK 0xff

#define MLX5_WQE_CTRL_WQE_INDEX_MASK 0x00ffff00

#define MLX5_WQE_CTRL_WQE_INDEX_SHIFT 8



struct mlx5_wqe_xrc_seg {

	__be32			xrc_srqn;
@@ -298,6 +303,8 @@ struct mlx5_wqe_signature_seg { 
	u8	rsvd1[11];

};



#define MLX5_WQE_INLINE_SEG_BYTE_COUNT_MASK 0x3ff



struct mlx5_wqe_inline_seg {

	__be32	byte_count;

};