[dpdk-dev] [PATCH 1/3] regex/mlx5: fix memory region unregistration

[Michael Baum <michaelba@nvidia.com>]

The issue can cause illegal physical address access while a huge-page A
is released and huge-page B is allocated on the same virtual address.
The old MR can be matched using the virtual address of huge-page B but
the HW will access the physical address of huge-page A which is no more
part of the DPDK process.

Register a driver callback for memory event in order to free out all the
MRs of memory that is going to be freed from the dpdk process.

Fixes: cda883bbb655 ("regex/mlx5: add dynamic memory registration to datapath")
Cc: stable@dpdk.org

Signed-off-by: Michael Baum <michaelba@nvidia.com>
---

This series depends on this patch:
https://patchwork.dpdk.org/project/dpdk/patch/20210628150614.1769507-1-michaelba@nvidia.com/
Please don't apply it only before this patch is integrated.

 drivers/regex/mlx5/mlx5_regex.c          | 55 ++++++++++++++++++++++++
 drivers/regex/mlx5/mlx5_regex.h          |  2 +
 drivers/regex/mlx5/mlx5_regex_fastpath.c | 39 +++++++++++++++--
 3 files changed, 92 insertions(+), 4 deletions(-)

diff --git a/drivers/regex/mlx5/mlx5_regex.c b/drivers/regex/mlx5/mlx5_regex.c
index dcb2ced88e..0f12d94d7e 100644
--- a/drivers/regex/mlx5/mlx5_regex.c
+++ b/drivers/regex/mlx5/mlx5_regex.c
@@ -11,6 +11,7 @@
 #include <rte_regexdev_driver.h>
 
 #include <mlx5_common_pci.h>
+#include <mlx5_common_mr.h>
 #include <mlx5_common.h>
 #include <mlx5_glue.h>
 #include <mlx5_devx_cmds.h>
@@ -24,6 +25,10 @@
 
 int mlx5_regex_logtype;
 
+TAILQ_HEAD(regex_mem_event, mlx5_regex_priv) mlx5_mem_event_list =
+				TAILQ_HEAD_INITIALIZER(mlx5_mem_event_list);
+static pthread_mutex_t mem_event_list_lock = PTHREAD_MUTEX_INITIALIZER;
+
 const struct rte_regexdev_ops mlx5_regexdev_ops = {
 	.dev_info_get = mlx5_regex_info_get,
 	.dev_configure = mlx5_regex_configure,
@@ -82,6 +87,40 @@ mlx5_regex_get_name(char *name, struct rte_pci_device *pci_dev __rte_unused)
 		pci_dev->addr.devid, pci_dev->addr.function);
 }
 
+/**
+ * Callback for memory event.
+ *
+ * @param event_type
+ *   Memory event type.
+ * @param addr
+ *   Address of memory.
+ * @param len
+ *   Size of memory.
+ */
+static void
+mlx5_regex_mr_mem_event_cb(enum rte_mem_event event_type, const void *addr,
+			   size_t len, void *arg __rte_unused)
+{
+	struct mlx5_regex_priv *priv;
+
+	/* Must be called from the primary process. */
+	MLX5_ASSERT(rte_eal_process_type() == RTE_PROC_PRIMARY);
+	switch (event_type) {
+	case RTE_MEM_EVENT_FREE:
+		pthread_mutex_lock(&mem_event_list_lock);
+		/* Iterate all the existing mlx5 devices. */
+		TAILQ_FOREACH(priv, &mlx5_mem_event_list, mem_event_cb)
+			mlx5_free_mr_by_addr(&priv->mr_scache,
+					     priv->ctx->device->name,
+					     addr, len);
+		pthread_mutex_unlock(&mem_event_list_lock);
+		break;
+	case RTE_MEM_EVENT_ALLOC:
+	default:
+		break;
+	}
+}
+
 static int
 mlx5_regex_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 		     struct rte_pci_device *pci_dev)
@@ -193,6 +232,15 @@ mlx5_regex_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
 	    rte_errno = ENOMEM;
 		goto error;
 	}
+	/* Register callback function for global shared MR cache management. */
+	if (TAILQ_EMPTY(&mlx5_mem_event_list))
+		rte_mem_event_callback_register("MLX5_MEM_EVENT_CB",
+						mlx5_regex_mr_mem_event_cb,
+						NULL);
+	/* Add device to memory callback list. */
+	pthread_mutex_lock(&mem_event_list_lock);
+	TAILQ_INSERT_TAIL(&mlx5_mem_event_list, priv, mem_event_cb);
+	pthread_mutex_unlock(&mem_event_list_lock);
 	DRV_LOG(INFO, "RegEx GGA is %s.",
 		priv->has_umr ? "supported" : "unsupported");
 	return 0;
@@ -225,6 +273,13 @@ mlx5_regex_pci_remove(struct rte_pci_device *pci_dev)
 		return 0;
 	priv = dev->data->dev_private;
 	if (priv) {
+		/* Remove from memory callback device list. */
+		pthread_mutex_lock(&mem_event_list_lock);
+		TAILQ_REMOVE(&mlx5_mem_event_list, priv, mem_event_cb);
+		pthread_mutex_unlock(&mem_event_list_lock);
+		if (TAILQ_EMPTY(&mlx5_mem_event_list))
+			rte_mem_event_callback_unregister("MLX5_MEM_EVENT_CB",
+							  NULL);
 		if (priv->pd)
 			mlx5_glue->dealloc_pd(priv->pd);
 		if (priv->uar)
diff --git a/drivers/regex/mlx5/mlx5_regex.h b/drivers/regex/mlx5/mlx5_regex.h
index 51a2101e53..61f59ba873 100644
--- a/drivers/regex/mlx5/mlx5_regex.h
+++ b/drivers/regex/mlx5/mlx5_regex.h
@@ -70,6 +70,8 @@ struct mlx5_regex_priv {
 	uint32_t nb_engines; /* Number of RegEx engines. */
 	struct mlx5dv_devx_uar *uar; /* UAR object. */
 	struct ibv_pd *pd;
+	TAILQ_ENTRY(mlx5_regex_priv) mem_event_cb;
+	/**< Called by memory event callback. */
 	struct mlx5_mr_share_cache mr_scache; /* Global shared MR cache. */
 	uint8_t is_bf2; /* The device is BF2 device. */
 	uint8_t sq_ts_format; /* Whether SQ supports timestamp formats. */
diff --git a/drivers/regex/mlx5/mlx5_regex_fastpath.c b/drivers/regex/mlx5/mlx5_regex_fastpath.c
index b57e7d7794..437009dcb6 100644
--- a/drivers/regex/mlx5/mlx5_regex_fastpath.c
+++ b/drivers/regex/mlx5/mlx5_regex_fastpath.c
@@ -109,6 +109,40 @@ set_wqe_ctrl_seg(struct mlx5_wqe_ctrl_seg *seg, uint16_t pi, uint8_t opcode,
 	seg->imm = imm;
 }
 
+/**
+ * Query LKey from a packet buffer for QP. If not found, add the mempool.
+ *
+ * @param priv
+ *   Pointer to the priv object.
+ * @param mr_ctrl
+ *   Pointer to per-queue MR control structure.
+ * @param op
+ *   Pointer to the RegEx operations object.
+ *
+ * @return
+ *   Searched LKey on success, UINT32_MAX on no match.
+ */
+static inline uint32_t
+mlx5_regex_addr2mr(struct mlx5_regex_priv *priv, struct mlx5_mr_ctrl *mr_ctrl,
+		   struct rte_regex_ops *op)
+{
+	uintptr_t addr = rte_pktmbuf_mtod(op->mbuf, uintptr_t);
+	uint32_t lkey;
+
+	/* Check generation bit to see if there's any change on existing MRs. */
+	if (unlikely(*mr_ctrl->dev_gen_ptr != mr_ctrl->cur_gen))
+		mlx5_mr_flush_local_cache(mr_ctrl);
+	/* Linear search on MR cache array. */
+	lkey = mlx5_mr_lookup_lkey(mr_ctrl->cache, &mr_ctrl->mru,
+				   MLX5_MR_CACHE_N, addr);
+	if (likely(lkey != UINT32_MAX))
+		return lkey;
+	/* Take slower bottom-half on miss. */
+	return mlx5_mr_addr2mr_bh(priv->pd, 0, &priv->mr_scache, mr_ctrl, addr,
+				  !!(op->mbuf->ol_flags & EXT_ATTACHED_MBUF));
+}
+
+
 static inline void
 __prep_one(struct mlx5_regex_priv *priv, struct mlx5_regex_sq *sq,
 	   struct rte_regex_ops *op, struct mlx5_regex_job *job,
@@ -160,10 +194,7 @@ prep_one(struct mlx5_regex_priv *priv, struct mlx5_regex_qp *qp,
 	struct mlx5_klm klm;
 
 	klm.byte_count = rte_pktmbuf_data_len(op->mbuf);
-	klm.mkey = mlx5_mr_addr2mr_bh(priv->pd, 0,
-				  &priv->mr_scache, &qp->mr_ctrl,
-				  rte_pktmbuf_mtod(op->mbuf, uintptr_t),
-				  !!(op->mbuf->ol_flags & EXT_ATTACHED_MBUF));
+	klm.mkey = mlx5_regex_addr2mr(priv, &qp->mr_ctrl, op);
 	klm.address = rte_pktmbuf_mtod(op->mbuf, uintptr_t);
 	__prep_one(priv, sq, op, job, sq->pi, &klm);
 	sq->db_pi = sq->pi;
-- 
2.25.1