[PATCH v7 09/23] nvme-tcp: Add modparam to control the ULP offload enablement

Aurelien Aptel
2022-10-25T14:01:56Z

Add ulp_offload module parameter to the nvme-tcp module to control
ULP offload at the NVMe-TCP layer.

Turn ULP offload off be default, regardless of the NIC driver support.

In summary, to enable ULP offload:
- nvme-tcp modparam must be set to 1
- the NIC driver must set
- NETIF_F_HW_ULP_DDP flag in netdev->features
- ULP_DDP_C_NVME_TCP and/or ULP_DDP_C_NVME_TCP_DDGST_RX
flags in ulp_limits->offload_capabilities

Signed-off-by: Yoray Zack <yorayz@nvidia.com>
Signed-off-by: Shai Malin <smalin@nvidia.com>
Signed-off-by: Aurelien Aptel <aaptel@nvidia.com>
---
drivers/nvme/host/tcp.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 8d83faf18321..4baebc475b79 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -34,6 +34,16 @@ static int so_priority;
module_param(so_priority, int, 0644);
MODULE_PARM_DESC(so_priority, "nvme tcp socket optimize priority");

+#ifdef CONFIG_ULP_DDP
+/* NVMeTCP direct data placement and data digest offload will not
+ * happen if this parameter false (default), regardless of what the
+ * underlying netdev capabilities are.
+ */
+static bool ulp_offload;
+module_param(ulp_offload, bool, 0644);
+MODULE_PARM_DESC(ulp_offload, "Enable or disable NVMeTCP ULP support");
+#endif
+
#ifdef CONFIG_DEBUG_LOCK_ALLOC
/* lockdep can detect a circular dependency of the form
* sk_lock -> mmap_lock (page fault) -> fs locks -> sk_lock
@@ -298,6 +308,9 @@ static bool nvme_tcp_ddp_query_limits(struct net_device *netdev,
{
int ret;

+ if (!ulp_offload)
+ return false;
+
if (!netdev || !(netdev->features & NETIF_F_HW_ULP_DDP) ||
!netdev->ulp_ddp_ops || !netdev->ulp_ddp_ops->ulp_ddp_limits)
return false;
@@ -497,6 +510,9 @@ static void nvme_tcp_offload_limits(struct nvme_tcp_queue *queue, struct net_dev
{
struct nvme_tcp_ddp_limits limits = {{ULP_DDP_NVME}};

+ if (!ulp_offload)
+ return;
+
if (!nvme_tcp_ddp_query_limits(netdev, &limits)) {
queue->ctrl->offloading_netdev = NULL;
return;
--
2.31.1