linux-kernel - [RFC PATCH v2 7/7] RDMA/rxe: Add support for the traditional Atomic operations with ODP

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Date:   Fri, 11 Nov 2022 18:22:28 +0900
From:   Daisuke Matsuda <matsuda-daisuke@...itsu.com>
To:     linux-rdma@...r.kernel.org, leonro@...dia.com, jgg@...dia.com,
        zyjzyj2000@...il.com
Cc:     nvdimm@...ts.linux.dev, linux-kernel@...r.kernel.org,
        rpearsonhpe@...il.com, yangx.jy@...itsu.com, lizhijian@...itsu.com,
        y-goto@...itsu.com, Daisuke Matsuda <matsuda-daisuke@...itsu.com>
Subject: [RFC PATCH v2 7/7] RDMA/rxe: Add support for the traditional Atomic operations with ODP

Enable 'fetch and add' and 'compare and swap' operations to manipulate
data in an ODP-enabled MR. This is comprised of the following steps:
 1. Check the driver page table(umem_odp->dma_list) to see if the target
    page is both readable and writable.
 2. If not, then trigger page fault to map the page.
 3. Convert its user space address to a kernel logical address using PFNs
    in the driver page table(umem_odp->pfn_list).
 4. Execute the operation.

umem_mutex is used to ensure that dma_list (an array of addresses of an MR)
is not changed while it is checked and that the target page is not
invalidated before data access completes.

Signed-off-by: Daisuke Matsuda <matsuda-daisuke@...itsu.com>
---
 drivers/infiniband/sw/rxe/rxe.c      |  1 +
 drivers/infiniband/sw/rxe/rxe_loc.h  |  2 ++
 drivers/infiniband/sw/rxe/rxe_odp.c  | 45 ++++++++++++++++++++++++++++
 drivers/infiniband/sw/rxe/rxe_resp.c |  2 +-
 drivers/infiniband/sw/rxe/rxe_resp.h |  3 ++
 5 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/sw/rxe/rxe.c b/drivers/infiniband/sw/rxe/rxe.c
index dd287fc60e9d..8190af3e9afe 100644
--- a/drivers/infiniband/sw/rxe/rxe.c
+++ b/drivers/infiniband/sw/rxe/rxe.c
@@ -88,6 +88,7 @@ static void rxe_init_device_param(struct rxe_dev *rxe)
 		rxe->attr.odp_caps.per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_RECV;
 		rxe->attr.odp_caps.per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_WRITE;
 		rxe->attr.odp_caps.per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_READ;
+		rxe->attr.odp_caps.per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_ATOMIC;
 		rxe->attr.odp_caps.per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_SRQ_RECV;
 	}
 }
diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h
index 8b19b6fdc497..6370dc31c83a 100644
--- a/drivers/infiniband/sw/rxe/rxe_loc.h
+++ b/drivers/infiniband/sw/rxe/rxe_loc.h
@@ -194,5 +194,7 @@ int rxe_create_user_odp_mr(struct ib_pd *pd, u64 start, u64 length, u64 iova,
 			   int access_flags, struct rxe_mr *mr);
 int rxe_odp_mr_copy(struct rxe_mr *mr, u64 iova, void *addr, int length,
 		    enum rxe_mr_copy_dir dir);
+enum resp_states rxe_odp_atomic_ops(struct rxe_qp *qp, struct rxe_pkt_info *pkt,
+				    struct rxe_mr *mr);
 
 #endif /* RXE_LOC_H */
diff --git a/drivers/infiniband/sw/rxe/rxe_odp.c b/drivers/infiniband/sw/rxe/rxe_odp.c
index ba4723818ee7..00aab9071737 100644
--- a/drivers/infiniband/sw/rxe/rxe_odp.c
+++ b/drivers/infiniband/sw/rxe/rxe_odp.c
@@ -289,3 +289,48 @@ int rxe_odp_mr_copy(struct rxe_mr *mr, u64 iova, void *addr, int length,
 
 	return err;
 }
+
+static inline void *rxe_odp_get_virt_atomic(struct rxe_qp *qp, struct rxe_mr *mr)
+{
+	struct ib_umem_odp *umem_odp = to_ib_umem_odp(mr->umem);
+	u64 iova = qp->resp.va + qp->resp.offset;
+	int idx;
+	size_t offset;
+
+	if (rxe_odp_map_range(mr, iova, sizeof(char), 0))
+		return NULL;
+
+	idx = (iova - ib_umem_start(umem_odp)) >> umem_odp->page_shift;
+	offset = iova & (BIT(umem_odp->page_shift) - 1);
+
+	return rxe_odp_get_virt(umem_odp, idx, offset);
+}
+
+enum resp_states rxe_odp_atomic_ops(struct rxe_qp *qp, struct rxe_pkt_info *pkt,
+				    struct rxe_mr *mr)
+{
+	struct ib_umem_odp *umem_odp = to_ib_umem_odp(mr->umem);
+	u64 *vaddr;
+	int ret;
+
+	if (unlikely(!mr->odp_enabled))
+		return RESPST_ERR_RKEY_VIOLATION;
+
+	/* If pagefault is not required, umem mutex will be held until an
+	 * atomic operation completes. Otherwise, it is released and locked
+	 * again in rxe_odp_map_range() to let invalidation handler do its
+	 * work meanwhile.
+	 */
+	mutex_lock(&umem_odp->umem_mutex);
+
+	vaddr = (u64 *)rxe_odp_get_virt_atomic(qp, mr);
+
+	if (pkt->mask & RXE_ATOMIC_MASK)
+		ret = rxe_process_atomic(qp, pkt, vaddr);
+	else
+		/* ATOMIC WRITE operation will come here. */
+		ret = RESPST_ERR_RKEY_VIOLATION;
+
+	mutex_unlock(&umem_odp->umem_mutex);
+	return ret;
+}
diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c
index 296b9ccee330..8e6a32c6c9e7 100644
--- a/drivers/infiniband/sw/rxe/rxe_resp.c
+++ b/drivers/infiniband/sw/rxe/rxe_resp.c
@@ -647,7 +647,7 @@ static enum resp_states rxe_atomic_reply(struct rxe_qp *qp,
 			return RESPST_ERR_RKEY_VIOLATION;
 
 		if (mr->odp_enabled)
-			ret = RESPST_ERR_UNSUPPORTED_OPCODE;
+			ret = rxe_odp_atomic_ops(qp, pkt, mr);
 		else
 			ret = rxe_atomic_ops(qp, pkt, mr);
 	} else
diff --git a/drivers/infiniband/sw/rxe/rxe_resp.h b/drivers/infiniband/sw/rxe/rxe_resp.h
index 121f0b998196..cb907b49175f 100644
--- a/drivers/infiniband/sw/rxe/rxe_resp.h
+++ b/drivers/infiniband/sw/rxe/rxe_resp.h
@@ -38,4 +38,7 @@ enum resp_states {
 	RESPST_EXIT,
 };
 
+enum resp_states rxe_process_atomic(struct rxe_qp *qp,
+				    struct rxe_pkt_info *pkt, u64 *vaddr);
+
 #endif /* RXE_RESP_H */
-- 
2.31.1