devlink: Add devlink reload limit option

Add reload limit to demand restrictions on reload actions.
Reload limits supported:
no_reset: No reset allowed, no down time allowed, no link flap and no
          configuration is lost.

By default reload limit is unspecified and so no constraints on reload
actions are required.

Some combinations of action and limit are invalid. For example, driver
can not reinitialize its entities without any downtime.

The no_reset reload limit will have usecase in this patchset to
implement restricted fw_activate on mlx5.

Have the uapi parameter of reload limit ready for future support of
multiselection.

Signed-off-by: Moshe Shemesh <moshe@mellanox.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 86 insertions, 6 deletions

diff --git a/net/core/devlink.c b/net/core/devlink.c
index c026ed3519c9..28b63faa3c6b 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -479,12 +479,44 @@ static int devlink_nl_put_handle(struct sk_buff *msg, struct devlink *devlink)
 	return 0;
 }
 
+struct devlink_reload_combination {
+	enum devlink_reload_action action;
+	enum devlink_reload_limit limit;
+};
+
+static const struct devlink_reload_combination devlink_reload_invalid_combinations[] = {
+	{
+		/* can't reinitialize driver with no down time */
+		.action = DEVLINK_RELOAD_ACTION_DRIVER_REINIT,
+		.limit = DEVLINK_RELOAD_LIMIT_NO_RESET,
+	},
+};
+
+static bool
+devlink_reload_combination_is_invalid(enum devlink_reload_action action,
+				      enum devlink_reload_limit limit)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(devlink_reload_invalid_combinations); i++)
+		if (devlink_reload_invalid_combinations[i].action == action &&
+		    devlink_reload_invalid_combinations[i].limit == limit)
+			return true;
+	return false;
+}
+
 static bool
 devlink_reload_action_is_supported(struct devlink *devlink, enum devlink_reload_action action)
 {
 	return test_bit(action, &devlink->ops->reload_actions);
 }
 
+static bool
+devlink_reload_limit_is_supported(struct devlink *devlink, enum devlink_reload_limit limit)
+{
+	return test_bit(limit, &devlink->ops->reload_limits);
+}
+
 static int devlink_nl_fill(struct sk_buff *msg, struct devlink *devlink,
 			   enum devlink_command cmd, u32 portid,
 			   u32 seq, int flags)
@@ -2990,22 +3022,22 @@ bool devlink_is_reload_failed(const struct devlink *devlink)
 EXPORT_SYMBOL_GPL(devlink_is_reload_failed);
 
 static int devlink_reload(struct devlink *devlink, struct net *dest_net,
-			  enum devlink_reload_action action, u32 *actions_performed,
-			  struct netlink_ext_ack *extack)
+			  enum devlink_reload_action action, enum devlink_reload_limit limit,
+			  u32 *actions_performed, struct netlink_ext_ack *extack)
 {
 	int err;
 
 	if (!devlink->reload_enabled)
 		return -EOPNOTSUPP;
 
-	err = devlink->ops->reload_down(devlink, !!dest_net, action, extack);
+	err = devlink->ops->reload_down(devlink, !!dest_net, action, limit, extack);
 	if (err)
 		return err;
 
 	if (dest_net && !net_eq(dest_net, devlink_net(devlink)))
 		devlink_reload_netns_change(devlink, dest_net);
 
-	err = devlink->ops->reload_up(devlink, action, actions_performed, extack);
+	err = devlink->ops->reload_up(devlink, action, limit, actions_performed, extack);
 	devlink_reload_failed_set(devlink, !!err);
 	if (err)
 		return err;
@@ -3050,6 +3082,7 @@ static int devlink_nl_cmd_reload(struct sk_buff *skb, struct genl_info *info)
 {
 	struct devlink *devlink = info->user_ptr[0];
 	enum devlink_reload_action action;
+	enum devlink_reload_limit limit;
 	struct net *dest_net = NULL;
 	u32 actions_performed;
 	int err;
@@ -3082,7 +3115,38 @@ static int devlink_nl_cmd_reload(struct sk_buff *skb, struct genl_info *info)
 		return -EOPNOTSUPP;
 	}
 
-	err = devlink_reload(devlink, dest_net, action, &actions_performed, info->extack);
+	limit = DEVLINK_RELOAD_LIMIT_UNSPEC;
+	if (info->attrs[DEVLINK_ATTR_RELOAD_LIMITS]) {
+		struct nla_bitfield32 limits;
+		u32 limits_selected;
+
+		limits = nla_get_bitfield32(info->attrs[DEVLINK_ATTR_RELOAD_LIMITS]);
+		limits_selected = limits.value & limits.selector;
+		if (!limits_selected) {
+			NL_SET_ERR_MSG_MOD(info->extack, "Invalid limit selected");
+			return -EINVAL;
+		}
+		for (limit = 0 ; limit <= DEVLINK_RELOAD_LIMIT_MAX ; limit++)
+			if (limits_selected & BIT(limit))
+				break;
+		/* UAPI enables multiselection, but currently it is not used */
+		if (limits_selected != BIT(limit)) {
+			NL_SET_ERR_MSG_MOD(info->extack,
+					   "Multiselection of limit is not supported");
+			return -EOPNOTSUPP;
+		}
+		if (!devlink_reload_limit_is_supported(devlink, limit)) {
+			NL_SET_ERR_MSG_MOD(info->extack,
+					   "Requested limit is not supported by the driver");
+			return -EOPNOTSUPP;
+		}
+		if (devlink_reload_combination_is_invalid(action, limit)) {
+			NL_SET_ERR_MSG_MOD(info->extack,
+					   "Requested limit is invalid for this action");
+			return -EINVAL;
+		}
+	}
+	err = devlink_reload(devlink, dest_net, action, limit, &actions_performed, info->extack);
 
 	if (dest_net)
 		put_net(dest_net);
@@ -3090,7 +3154,7 @@ static int devlink_nl_cmd_reload(struct sk_buff *skb, struct genl_info *info)
 	if (err)
 		return err;
 	/* For backward compatibility generate reply only if attributes used by user */
-	if (!info->attrs[DEVLINK_ATTR_RELOAD_ACTION])
+	if (!info->attrs[DEVLINK_ATTR_RELOAD_ACTION] && !info->attrs[DEVLINK_ATTR_RELOAD_LIMITS])
 		return 0;
 
 	return devlink_nl_reload_actions_performed_snd(devlink, actions_performed,
@@ -7347,6 +7411,7 @@ static const struct nla_policy devlink_nl_policy[DEVLINK_ATTR_MAX + 1] = {
 	[DEVLINK_ATTR_PORT_FUNCTION] = { .type = NLA_NESTED },
 	[DEVLINK_ATTR_RELOAD_ACTION] = NLA_POLICY_RANGE(NLA_U8, DEVLINK_RELOAD_ACTION_DRIVER_REINIT,
 							DEVLINK_RELOAD_ACTION_MAX),
+	[DEVLINK_ATTR_RELOAD_LIMITS] = NLA_POLICY_BITFIELD32(DEVLINK_RELOAD_LIMITS_VALID_MASK),
 };
 
 static const struct genl_small_ops devlink_nl_ops[] = {
@@ -7682,6 +7747,9 @@ static struct genl_family devlink_nl_family __ro_after_init = {
 
 static bool devlink_reload_actions_valid(const struct devlink_ops *ops)
 {
+	const struct devlink_reload_combination *comb;
+	int i;
+
 	if (!devlink_reload_supported(ops)) {
 		if (WARN_ON(ops->reload_actions))
 			return false;
@@ -7692,6 +7760,17 @@ static bool devlink_reload_actions_valid(const struct devlink_ops *ops)
 		    ops->reload_actions & BIT(DEVLINK_RELOAD_ACTION_UNSPEC) ||
 		    ops->reload_actions >= BIT(__DEVLINK_RELOAD_ACTION_MAX)))
 		return false;
+
+	if (WARN_ON(ops->reload_limits & BIT(DEVLINK_RELOAD_LIMIT_UNSPEC) ||
+		    ops->reload_limits >= BIT(__DEVLINK_RELOAD_LIMIT_MAX)))
+		return false;
+
+	for (i = 0; i < ARRAY_SIZE(devlink_reload_invalid_combinations); i++)  {
+		comb = &devlink_reload_invalid_combinations[i];
+		if (ops->reload_actions == BIT(comb->action) &&
+		    ops->reload_limits == BIT(comb->limit))
+			return false;
+	}
 	return true;
 }
 
@@ -10056,6 +10135,7 @@ static void __net_exit devlink_pernet_pre_exit(struct net *net)
 				continue;
 			err = devlink_reload(devlink, &init_net,
 					     DEVLINK_RELOAD_ACTION_DRIVER_REINIT,
+					     DEVLINK_RELOAD_LIMIT_UNSPEC,
 					     &actions_performed, NULL);
 			if (err && err != -EOPNOTSUPP)
 				pr_warn("Failed to reload devlink instance into init_net\n");