Merge branch 'Add-packet-trap-policers-support'

Ido Schimmel says:

====================
Add packet trap policers support

Background
==========

Devices capable of offloading the kernel's datapath and perform
functions such as bridging and routing must also be able to send (trap)
specific packets to the kernel (i.e., the CPU) for processing.

For example, a device acting as a multicast-aware bridge must be able to
trap IGMP membership reports to the kernel for processing by the bridge
module.

Motivation
==========

In most cases, the underlying device is capable of handling packet rates
that are several orders of magnitude higher compared to those that can
be handled by the CPU.

Therefore, in order to prevent the underlying device from overwhelming
the CPU, devices usually include packet trap policers that are able to
police the trapped packets to rates that can be handled by the CPU.

Proposed solution
=================

This patch set allows capable device drivers to register their supported
packet trap policers with devlink. User space can then tune the
parameters of these policers (currently, rate and burst size) and read
from the device the number of packets that were dropped by the policer,
if supported.

These packet trap policers can then be bound to existing packet trap
groups, which are used to aggregate logically related packet traps. As a
result, trapped packets are policed to rates that can be handled the
host CPU.

Example usage
=============

Instantiate netdevsim:

Dump available packet trap policers:
netdevsim/netdevsim10:
  policer 1 rate 1000 burst 128
  policer 2 rate 2000 burst 256
  policer 3 rate 3000 burst 512

Change the parameters of a packet trap policer:

Bind a packet trap policer to a packet trap group:

Dump parameters and statistics of a packet trap policer:
netdevsim/netdevsim10:
  policer 3 rate 100 burst 16
    stats:
        rx:
          dropped 92

Unbind a packet trap policer from a packet trap group:

Patch set overview
==================

Patch #1 adds the core infrastructure in devlink which allows capable
device drivers to register their supported packet trap policers with
devlink.

Patch #2 extends the existing devlink-trap documentation.

Patch #3 extends netdevsim to register a few dummy packet trap policers
with devlink. Used later on to selftests the core infrastructure.

Patches #4-#5 adds infrastructure in devlink to allow binding of packet
trap policers to packet trap groups.

Patch #6 extends netdevsim to allow such binding.

Patch #7 adds a selftest over netdevsim that verifies the core
devlink-trap policers functionality.

Patches #8-#14 gradually add devlink-trap policers support in mlxsw.

Patch #15 adds a selftest over mlxsw. All registered packet trap
policers are verified to handle the configured rate and burst size.

Future plans
============

* Allow changing default association between packet traps and packet
  trap groups
* Add more packet traps. For example, for control packets (e.g., IGMP)

v3:
* Rebase

v2 (address comments from Jiri and Jakub):
* Patch #1: Add 'strict_start_type' in devlink policy
* Patch #1: Have device drivers provide max/min rate/burst size for each
  policer. Use them to check validity of user provided parameters
* Patch #3: Remove check about burst size being a power of 2 and instead
  add a debugfs knob to fail the operation
* Patch #3: Provide max/min rate/burst size when registering policers
  and remove the validity checks from nsim_dev_devlink_trap_policer_set()
* Patch #5: Check for presence of 'DEVLINK_ATTR_TRAP_POLICER_ID' in
  devlink_trap_group_set() and bail if not present
* Patch #5: Add extack error message in case trap group was partially
  modified
* Patch #7: Add test case with new 'fail_trap_policer_set' knob
* Patch #7: Add test case for partially modified trap group
* Patch #10: Provide max/min rate/burst size when registering policers
* Patch #11: Remove the max/min validity checks from
  __mlxsw_sp_trap_policer_set()
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 105 insertions, 5 deletions

diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
index 2b727a7001f6..1fe2a93ad382 100644
--- a/drivers/net/netdevsim/dev.c
+++ b/drivers/net/netdevsim/dev.c
@@ -215,6 +215,15 @@ static int nsim_dev_debugfs_init(struct nsim_dev *nsim_dev)
 			    &nsim_dev->fail_reload);
 	debugfs_create_file("trap_flow_action_cookie", 0600, nsim_dev->ddir,
 			    nsim_dev, &nsim_dev_trap_fa_cookie_fops);
+	debugfs_create_bool("fail_trap_group_set", 0600,
+			    nsim_dev->ddir,
+			    &nsim_dev->fail_trap_group_set);
+	debugfs_create_bool("fail_trap_policer_set", 0600,
+			    nsim_dev->ddir,
+			    &nsim_dev->fail_trap_policer_set);
+	debugfs_create_bool("fail_trap_policer_counter_get", 0600,
+			    nsim_dev->ddir,
+			    &nsim_dev->fail_trap_policer_counter_get);
 	return 0;
 }
 
@@ -392,6 +401,7 @@ struct nsim_trap_item {
 struct nsim_trap_data {
 	struct delayed_work trap_report_dw;
 	struct nsim_trap_item *trap_items_arr;
+	u64 *trap_policers_cnt_arr;
 	struct nsim_dev *nsim_dev;
 	spinlock_t trap_lock;	/* Protects trap_items_arr */
 };
@@ -426,11 +436,29 @@ enum {
 			    DEVLINK_TRAP_GROUP_GENERIC_ID_##_group_id,	      \
 			    NSIM_TRAP_METADATA)
 
+#define NSIM_DEV_TRAP_POLICER_MIN_RATE	1
+#define NSIM_DEV_TRAP_POLICER_MAX_RATE	8000
+#define NSIM_DEV_TRAP_POLICER_MIN_BURST	8
+#define NSIM_DEV_TRAP_POLICER_MAX_BURST	65536
+
+#define NSIM_TRAP_POLICER(_id, _rate, _burst)				      \
+	DEVLINK_TRAP_POLICER(_id, _rate, _burst,			      \
+			     NSIM_DEV_TRAP_POLICER_MAX_RATE,		      \
+			     NSIM_DEV_TRAP_POLICER_MIN_RATE,		      \
+			     NSIM_DEV_TRAP_POLICER_MAX_BURST,		      \
+			     NSIM_DEV_TRAP_POLICER_MIN_BURST)
+
+static const struct devlink_trap_policer nsim_trap_policers_arr[] = {
+	NSIM_TRAP_POLICER(1, 1000, 128),
+	NSIM_TRAP_POLICER(2, 2000, 256),
+	NSIM_TRAP_POLICER(3, 3000, 512),
+};
+
 static const struct devlink_trap_group nsim_trap_groups_arr[] = {
-	DEVLINK_TRAP_GROUP_GENERIC(L2_DROPS),
-	DEVLINK_TRAP_GROUP_GENERIC(L3_DROPS),
-	DEVLINK_TRAP_GROUP_GENERIC(BUFFER_DROPS),
-	DEVLINK_TRAP_GROUP_GENERIC(ACL_DROPS),
+	DEVLINK_TRAP_GROUP_GENERIC(L2_DROPS, 0),
+	DEVLINK_TRAP_GROUP_GENERIC(L3_DROPS, 1),
+	DEVLINK_TRAP_GROUP_GENERIC(BUFFER_DROPS, 2),
+	DEVLINK_TRAP_GROUP_GENERIC(ACL_DROPS, 3),
 };
 
 static const struct devlink_trap nsim_traps_arr[] = {
@@ -568,6 +596,7 @@ static void nsim_dev_trap_report_work(struct work_struct *work)
 
 static int nsim_dev_traps_init(struct devlink *devlink)
 {
+	size_t policers_count = ARRAY_SIZE(nsim_trap_policers_arr);
 	struct nsim_dev *nsim_dev = devlink_priv(devlink);
 	struct nsim_trap_data *nsim_trap_data;
 	int err;
@@ -584,6 +613,14 @@ static int nsim_dev_traps_init(struct devlink *devlink)
 		goto err_trap_data_free;
 	}
 
+	nsim_trap_data->trap_policers_cnt_arr = kcalloc(policers_count,
+							sizeof(u64),
+							GFP_KERNEL);
+	if (!nsim_trap_data->trap_policers_cnt_arr) {
+		err = -ENOMEM;
+		goto err_trap_items_free;
+	}
+
 	/* The lock is used to protect the action state of the registered
 	 * traps. The value is written by user and read in delayed work when
 	 * iterating over all the traps.
@@ -592,10 +629,15 @@ static int nsim_dev_traps_init(struct devlink *devlink)
 	nsim_trap_data->nsim_dev = nsim_dev;
 	nsim_dev->trap_data = nsim_trap_data;
 
+	err = devlink_trap_policers_register(devlink, nsim_trap_policers_arr,
+					     policers_count);
+	if (err)
+		goto err_trap_policers_cnt_free;
+
 	err = devlink_trap_groups_register(devlink, nsim_trap_groups_arr,
 					   ARRAY_SIZE(nsim_trap_groups_arr));
 	if (err)
-		goto err_trap_items_free;
+		goto err_trap_policers_unregister;
 
 	err = devlink_traps_register(devlink, nsim_traps_arr,
 				     ARRAY_SIZE(nsim_traps_arr), NULL);
@@ -612,6 +654,11 @@ static int nsim_dev_traps_init(struct devlink *devlink)
 err_trap_groups_unregister:
 	devlink_trap_groups_unregister(devlink, nsim_trap_groups_arr,
 				       ARRAY_SIZE(nsim_trap_groups_arr));
+err_trap_policers_unregister:
+	devlink_trap_policers_unregister(devlink, nsim_trap_policers_arr,
+					 ARRAY_SIZE(nsim_trap_policers_arr));
+err_trap_policers_cnt_free:
+	kfree(nsim_trap_data->trap_policers_cnt_arr);
 err_trap_items_free:
 	kfree(nsim_trap_data->trap_items_arr);
 err_trap_data_free:
@@ -628,6 +675,9 @@ static void nsim_dev_traps_exit(struct devlink *devlink)
 				 ARRAY_SIZE(nsim_traps_arr));
 	devlink_trap_groups_unregister(devlink, nsim_trap_groups_arr,
 				       ARRAY_SIZE(nsim_trap_groups_arr));
+	devlink_trap_policers_unregister(devlink, nsim_trap_policers_arr,
+					 ARRAY_SIZE(nsim_trap_policers_arr));
+	kfree(nsim_dev->trap_data->trap_policers_cnt_arr);
 	kfree(nsim_dev->trap_data->trap_items_arr);
 	kfree(nsim_dev->trap_data);
 }
@@ -766,6 +816,53 @@ nsim_dev_devlink_trap_action_set(struct devlink *devlink,
 	return 0;
 }
 
+static int
+nsim_dev_devlink_trap_group_set(struct devlink *devlink,
+				const struct devlink_trap_group *group,
+				const struct devlink_trap_policer *policer)
+{
+	struct nsim_dev *nsim_dev = devlink_priv(devlink);
+
+	if (nsim_dev->fail_trap_group_set)
+		return -EINVAL;
+
+	return 0;
+}
+
+static int
+nsim_dev_devlink_trap_policer_set(struct devlink *devlink,
+				  const struct devlink_trap_policer *policer,
+				  u64 rate, u64 burst,
+				  struct netlink_ext_ack *extack)
+{
+	struct nsim_dev *nsim_dev = devlink_priv(devlink);
+
+	if (nsim_dev->fail_trap_policer_set) {
+		NL_SET_ERR_MSG_MOD(extack, "User setup the operation to fail for testing purposes");
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static int
+nsim_dev_devlink_trap_policer_counter_get(struct devlink *devlink,
+					  const struct devlink_trap_policer *policer,
+					  u64 *p_drops)
+{
+	struct nsim_dev *nsim_dev = devlink_priv(devlink);
+	u64 *cnt;
+
+	if (nsim_dev->fail_trap_policer_counter_get)
+		return -EINVAL;
+
+	cnt = &nsim_dev->trap_data->trap_policers_cnt_arr[policer->id - 1];
+	*p_drops = *cnt;
+	*cnt += jiffies % 64;
+
+	return 0;
+}
+
 static const struct devlink_ops nsim_dev_devlink_ops = {
 	.reload_down = nsim_dev_reload_down,
 	.reload_up = nsim_dev_reload_up,
@@ -773,6 +870,9 @@ static const struct devlink_ops nsim_dev_devlink_ops = {
 	.flash_update = nsim_dev_flash_update,
 	.trap_init = nsim_dev_devlink_trap_init,
 	.trap_action_set = nsim_dev_devlink_trap_action_set,
+	.trap_group_set = nsim_dev_devlink_trap_group_set,
+	.trap_policer_set = nsim_dev_devlink_trap_policer_set,
+	.trap_policer_counter_get = nsim_dev_devlink_trap_policer_counter_get,
 };
 
 #define NSIM_DEV_MAX_MACS_DEFAULT 32