nvmf: Add a transport hook to limit the maximum command capsule size

NVMe controllers advertise the largest supported size of a command
capsule in the controller data (IOCCSZ).  Smart NIC offload transports
may have a cap on the size of the largest data PDU that can be
received.  These transports can implement this hook to limit the
advertised IOCCSZ to limit the in-capsule-data payload sent by remote
hosts.

Sponsored by:	Chelsio Communications

4 files changed, 22 insertions, 0 deletions

diff --git a/sys/dev/nvmf/nvmf_tcp.c b/sys/dev/nvmf/nvmf_tcp.c
index 0e31c0495775..481c769cedcb 100644
--- a/sys/dev/nvmf/nvmf_tcp.c
+++ b/sys/dev/nvmf/nvmf_tcp.c
@@ -1602,6 +1602,12 @@ tcp_free_qpair(struct nvmf_qpair *nq)
 	tcp_release_qpair(qp);
 }
 
+static uint32_t
+tcp_max_ioccsz(struct nvmf_qpair *nq)
+{
+	return (0);
+}
+
 static uint64_t
 tcp_max_xfer_size(struct nvmf_qpair *nq)
 {
@@ -1878,6 +1884,7 @@ tcp_send_controller_data(struct nvmf_capsule *nc, uint32_t data_offset,
 struct nvmf_transport_ops tcp_ops = {
 	.allocate_qpair = tcp_allocate_qpair,
 	.free_qpair = tcp_free_qpair,
+	.max_ioccsz = tcp_max_ioccsz,
 	.max_xfer_size = tcp_max_xfer_size,
 	.allocate_capsule = tcp_allocate_capsule,
 	.free_capsule = tcp_free_capsule,
diff --git a/sys/dev/nvmf/nvmf_transport.c b/sys/dev/nvmf/nvmf_transport.c
index d552393f7adf..92d71d1b13fd 100644
--- a/sys/dev/nvmf/nvmf_transport.c
+++ b/sys/dev/nvmf/nvmf_transport.c
@@ -194,6 +194,12 @@ nvmf_max_xfer_size(struct nvmf_qpair *qp)
 	return (qp->nq_ops->max_xfer_size(qp));
 }
 
+uint32_t
+nvmf_max_ioccsz(struct nvmf_qpair *qp)
+{
+	return (qp->nq_ops->max_ioccsz(qp));
+}
+
 uint8_t
 nvmf_validate_command_capsule(struct nvmf_capsule *nc)
 {
diff --git a/sys/dev/nvmf/nvmf_transport.h b/sys/dev/nvmf/nvmf_transport.h
index 38b661ab3c91..495e0dbc8c37 100644
--- a/sys/dev/nvmf/nvmf_transport.h
+++ b/sys/dev/nvmf/nvmf_transport.h
@@ -92,6 +92,12 @@ uint64_t nvmf_max_xfer_size(struct nvmf_qpair *qp);
 /* Controller-specific APIs. */
 
 /*
+ * Largest I/O command capsule size (IOCCSZ) supported by the
+ * transport.  If the transport does not have a limit, returns 0.
+ */
+uint32_t nvmf_max_ioccsz(struct nvmf_qpair *qp);
+
+/*
  * A controller calls this function to check for any
  * transport-specific errors (invalid fields) in a received command
  * capsule.  The callback returns a generic command status value:
diff --git a/sys/dev/nvmf/nvmf_transport_internal.h b/sys/dev/nvmf/nvmf_transport_internal.h
index 511aac120fdc..9b459716168a 100644
--- a/sys/dev/nvmf/nvmf_transport_internal.h
+++ b/sys/dev/nvmf/nvmf_transport_internal.h
@@ -25,6 +25,9 @@ struct nvmf_transport_ops {
 	    const nvlist_t *nvl);
 	void (*free_qpair)(struct nvmf_qpair *qp);
 
+	/* Limit on I/O command capsule size. */
+	uint32_t (*max_ioccsz)(struct nvmf_qpair *qp);
+
 	/* Limit on transfer size. */
 	uint64_t (*max_xfer_size)(struct nvmf_qpair *qp);