Merge branch 'mlxsw-Support-DSCP-prioritization-and-rewrite'

Ido Schimmel says:

====================
mlxsw: Support DSCP prioritization and rewrite

Petr says:

On ingress, a network device such as a switch assigns to packets
priority based on various criteria. Common options include interpreting
PCP and DSCP fields according to user configuration. When a packet
egresses the switch, a reverse process may rewrite PCP and/or DSCP
headers according to packet priority.

So far, mlxsw has supported prioritization based on PCP (802.1p priority
tag). This patch set introduces support for prioritization based on
DSCP, and DSCP rewrite.

To configure the DSCP-to-priority maps, the user is expected to invoke
ieee_setapp and ieee_delapp DCBNL ops, e.g. by using lldptool:

To decide whether or not to pay attention to DSCP values, the Spectrum
switch recognize a per-port configuration of trust level. Until the
first APP rule is added for a given port, this port's trust level stays
at PCP, meaning that PCP is used for packet prioritization. With the
first DSCP APP rule, the port is configured to trust DSCP instead, and
it stays there until all DSCP APP rules are removed again.

Besides the DSCP (value 5) selector, another selector that plays into
packet prioritization is Ethernet type (value 1) with PID of 0. Such APP
entries denote default priority[1]:

With this patch set, mlxsw uses these values to configure priority for
DSCP values not explicitly specified in DSCP APP map. In the future we
expect to also use this to configure default port priority for untagged
packets.

Access to DSCP-to-priority map, priority-to-DSCP map, and default
priority for a port is exposed through three new DCB helpers. Like the
already-existing dcb_ieee_getapp_mask() helper, these helpers operate in
terms of bitmaps, to support the arbitrary M:N mapping that the APP
rules allow. Such interface presents all the relevant information from
the APP database without necessitating exposition of iterators, locking
or other complex primitives. It is up to the driver to then digest the
mapping in a way that the device supports. In this patch set, mlxsw
resolves conflicts by favoring higher-numbered DSCP values and
priorities.

In this patchset:

- Patch #1 fixes a bug in DCB APP database management.
- Patch #2 adds the getters described above.
- Patches #3-#6 add Spectrum configuration registers.
- Patch #7 adds the mlxsw logic that configures the device according to
  APP rules.
- Patch #8 adds a self-test. The test is added to the subdirectory
  drivers/net/mlxsw. Even though it's not particularly specific to
  mlxsw, it's not suitable for running on soft devices (which don't
  support the ieee_getapp et.al.), and thus isn't a good fit for the
  general net/forwarding directory.

[1] 802.1Q-2014, Table D-9
====================

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

6 files changed, 844 insertions, 6 deletions

diff --git a/drivers/net/ethernet/mellanox/mlxsw/reg.h b/drivers/net/ethernet/mellanox/mlxsw/reg.h
index fd2e3dd166d2..e52841627966 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/reg.h
+++ b/drivers/net/ethernet/mellanox/mlxsw/reg.h
@@ -3017,6 +3017,44 @@ static inline void mlxsw_reg_iedr_rec_pack(char *payload, int rec_index,
 	mlxsw_reg_iedr_rec_index_start_set(payload, rec_index, rec_index_start);
 }
 
+/* QPTS - QoS Priority Trust State Register
+ * ----------------------------------------
+ * This register controls the port policy to calculate the switch priority and
+ * packet color based on incoming packet fields.
+ */
+#define MLXSW_REG_QPTS_ID 0x4002
+#define MLXSW_REG_QPTS_LEN 0x8
+
+MLXSW_REG_DEFINE(qpts, MLXSW_REG_QPTS_ID, MLXSW_REG_QPTS_LEN);
+
+/* reg_qpts_local_port
+ * Local port number.
+ * Access: Index
+ *
+ * Note: CPU port is supported.
+ */
+MLXSW_ITEM32(reg, qpts, local_port, 0x00, 16, 8);
+
+enum mlxsw_reg_qpts_trust_state {
+	MLXSW_REG_QPTS_TRUST_STATE_PCP = 1,
+	MLXSW_REG_QPTS_TRUST_STATE_DSCP = 2, /* For MPLS, trust EXP. */
+};
+
+/* reg_qpts_trust_state
+ * Trust state for a given port.
+ * Access: RW
+ */
+MLXSW_ITEM32(reg, qpts, trust_state, 0x04, 0, 3);
+
+static inline void mlxsw_reg_qpts_pack(char *payload, u8 local_port,
+				       enum mlxsw_reg_qpts_trust_state ts)
+{
+	MLXSW_REG_ZERO(qpts, payload);
+
+	mlxsw_reg_qpts_local_port_set(payload, local_port);
+	mlxsw_reg_qpts_trust_state_set(payload, ts);
+}
+
 /* QPCR - QoS Policer Configuration Register
  * -----------------------------------------
  * The QPCR register is used to create policers - that limit
@@ -3329,6 +3367,183 @@ static inline void mlxsw_reg_qeec_pack(char *payload, u8 local_port,
 	mlxsw_reg_qeec_next_element_index_set(payload, next_index);
 }
 
+/* QRWE - QoS ReWrite Enable
+ * -------------------------
+ * This register configures the rewrite enable per receive port.
+ */
+#define MLXSW_REG_QRWE_ID 0x400F
+#define MLXSW_REG_QRWE_LEN 0x08
+
+MLXSW_REG_DEFINE(qrwe, MLXSW_REG_QRWE_ID, MLXSW_REG_QRWE_LEN);
+
+/* reg_qrwe_local_port
+ * Local port number.
+ * Access: Index
+ *
+ * Note: CPU port is supported. No support for router port.
+ */
+MLXSW_ITEM32(reg, qrwe, local_port, 0x00, 16, 8);
+
+/* reg_qrwe_dscp
+ * Whether to enable DSCP rewrite (default is 0, don't rewrite).
+ * Access: RW
+ */
+MLXSW_ITEM32(reg, qrwe, dscp, 0x04, 1, 1);
+
+/* reg_qrwe_pcp
+ * Whether to enable PCP and DEI rewrite (default is 0, don't rewrite).
+ * Access: RW
+ */
+MLXSW_ITEM32(reg, qrwe, pcp, 0x04, 0, 1);
+
+static inline void mlxsw_reg_qrwe_pack(char *payload, u8 local_port,
+				       bool rewrite_pcp, bool rewrite_dscp)
+{
+	MLXSW_REG_ZERO(qrwe, payload);
+	mlxsw_reg_qrwe_local_port_set(payload, local_port);
+	mlxsw_reg_qrwe_pcp_set(payload, rewrite_pcp);
+	mlxsw_reg_qrwe_dscp_set(payload, rewrite_dscp);
+}
+
+/* QPDSM - QoS Priority to DSCP Mapping
+ * ------------------------------------
+ * QoS Priority to DSCP Mapping Register
+ */
+#define MLXSW_REG_QPDSM_ID 0x4011
+#define MLXSW_REG_QPDSM_BASE_LEN 0x04 /* base length, without records */
+#define MLXSW_REG_QPDSM_PRIO_ENTRY_REC_LEN 0x4 /* record length */
+#define MLXSW_REG_QPDSM_PRIO_ENTRY_REC_MAX_COUNT 16
+#define MLXSW_REG_QPDSM_LEN (MLXSW_REG_QPDSM_BASE_LEN +			\
+			     MLXSW_REG_QPDSM_PRIO_ENTRY_REC_LEN *	\
+			     MLXSW_REG_QPDSM_PRIO_ENTRY_REC_MAX_COUNT)
+
+MLXSW_REG_DEFINE(qpdsm, MLXSW_REG_QPDSM_ID, MLXSW_REG_QPDSM_LEN);
+
+/* reg_qpdsm_local_port
+ * Local Port. Supported for data packets from CPU port.
+ * Access: Index
+ */
+MLXSW_ITEM32(reg, qpdsm, local_port, 0x00, 16, 8);
+
+/* reg_qpdsm_prio_entry_color0_e
+ * Enable update of the entry for color 0 and a given port.
+ * Access: WO
+ */
+MLXSW_ITEM32_INDEXED(reg, qpdsm, prio_entry_color0_e,
+		     MLXSW_REG_QPDSM_BASE_LEN, 31, 1,
+		     MLXSW_REG_QPDSM_PRIO_ENTRY_REC_LEN, 0x00, false);
+
+/* reg_qpdsm_prio_entry_color0_dscp
+ * DSCP field in the outer label of the packet for color 0 and a given port.
+ * Reserved when e=0.
+ * Access: RW
+ */
+MLXSW_ITEM32_INDEXED(reg, qpdsm, prio_entry_color0_dscp,
+		     MLXSW_REG_QPDSM_BASE_LEN, 24, 6,
+		     MLXSW_REG_QPDSM_PRIO_ENTRY_REC_LEN, 0x00, false);
+
+/* reg_qpdsm_prio_entry_color1_e
+ * Enable update of the entry for color 1 and a given port.
+ * Access: WO
+ */
+MLXSW_ITEM32_INDEXED(reg, qpdsm, prio_entry_color1_e,
+		     MLXSW_REG_QPDSM_BASE_LEN, 23, 1,
+		     MLXSW_REG_QPDSM_PRIO_ENTRY_REC_LEN, 0x00, false);
+
+/* reg_qpdsm_prio_entry_color1_dscp
+ * DSCP field in the outer label of the packet for color 1 and a given port.
+ * Reserved when e=0.
+ * Access: RW
+ */
+MLXSW_ITEM32_INDEXED(reg, qpdsm, prio_entry_color1_dscp,
+		     MLXSW_REG_QPDSM_BASE_LEN, 16, 6,
+		     MLXSW_REG_QPDSM_PRIO_ENTRY_REC_LEN, 0x00, false);
+
+/* reg_qpdsm_prio_entry_color2_e
+ * Enable update of the entry for color 2 and a given port.
+ * Access: WO
+ */
+MLXSW_ITEM32_INDEXED(reg, qpdsm, prio_entry_color2_e,
+		     MLXSW_REG_QPDSM_BASE_LEN, 15, 1,
+		     MLXSW_REG_QPDSM_PRIO_ENTRY_REC_LEN, 0x00, false);
+
+/* reg_qpdsm_prio_entry_color2_dscp
+ * DSCP field in the outer label of the packet for color 2 and a given port.
+ * Reserved when e=0.
+ * Access: RW
+ */
+MLXSW_ITEM32_INDEXED(reg, qpdsm, prio_entry_color2_dscp,
+		     MLXSW_REG_QPDSM_BASE_LEN, 8, 6,
+		     MLXSW_REG_QPDSM_PRIO_ENTRY_REC_LEN, 0x00, false);
+
+static inline void mlxsw_reg_qpdsm_pack(char *payload, u8 local_port)
+{
+	MLXSW_REG_ZERO(qpdsm, payload);
+	mlxsw_reg_qpdsm_local_port_set(payload, local_port);
+}
+
+static inline void
+mlxsw_reg_qpdsm_prio_pack(char *payload, unsigned short prio, u8 dscp)
+{
+	mlxsw_reg_qpdsm_prio_entry_color0_e_set(payload, prio, 1);
+	mlxsw_reg_qpdsm_prio_entry_color0_dscp_set(payload, prio, dscp);
+	mlxsw_reg_qpdsm_prio_entry_color1_e_set(payload, prio, 1);
+	mlxsw_reg_qpdsm_prio_entry_color1_dscp_set(payload, prio, dscp);
+	mlxsw_reg_qpdsm_prio_entry_color2_e_set(payload, prio, 1);
+	mlxsw_reg_qpdsm_prio_entry_color2_dscp_set(payload, prio, dscp);
+}
+
+/* QPDPM - QoS Port DSCP to Priority Mapping Register
+ * --------------------------------------------------
+ * This register controls the mapping from DSCP field to
+ * Switch Priority for IP packets.
+ */
+#define MLXSW_REG_QPDPM_ID 0x4013
+#define MLXSW_REG_QPDPM_BASE_LEN 0x4 /* base length, without records */
+#define MLXSW_REG_QPDPM_DSCP_ENTRY_REC_LEN 0x2 /* record length */
+#define MLXSW_REG_QPDPM_DSCP_ENTRY_REC_MAX_COUNT 64
+#define MLXSW_REG_QPDPM_LEN (MLXSW_REG_QPDPM_BASE_LEN +			\
+			     MLXSW_REG_QPDPM_DSCP_ENTRY_REC_LEN *	\
+			     MLXSW_REG_QPDPM_DSCP_ENTRY_REC_MAX_COUNT)
+
+MLXSW_REG_DEFINE(qpdpm, MLXSW_REG_QPDPM_ID, MLXSW_REG_QPDPM_LEN);
+
+/* reg_qpdpm_local_port
+ * Local Port. Supported for data packets from CPU port.
+ * Access: Index
+ */
+MLXSW_ITEM32(reg, qpdpm, local_port, 0x00, 16, 8);
+
+/* reg_qpdpm_dscp_e
+ * Enable update of the specific entry. When cleared, the switch_prio and color
+ * fields are ignored and the previous switch_prio and color values are
+ * preserved.
+ * Access: WO
+ */
+MLXSW_ITEM16_INDEXED(reg, qpdpm, dscp_entry_e, MLXSW_REG_QPDPM_BASE_LEN, 15, 1,
+		     MLXSW_REG_QPDPM_DSCP_ENTRY_REC_LEN, 0x00, false);
+
+/* reg_qpdpm_dscp_prio
+ * The new Switch Priority value for the relevant DSCP value.
+ * Access: RW
+ */
+MLXSW_ITEM16_INDEXED(reg, qpdpm, dscp_entry_prio,
+		     MLXSW_REG_QPDPM_BASE_LEN, 0, 4,
+		     MLXSW_REG_QPDPM_DSCP_ENTRY_REC_LEN, 0x00, false);
+
+static inline void mlxsw_reg_qpdpm_pack(char *payload, u8 local_port)
+{
+	MLXSW_REG_ZERO(qpdpm, payload);
+	mlxsw_reg_qpdpm_local_port_set(payload, local_port);
+}
+
+static inline void
+mlxsw_reg_qpdpm_dscp_pack(char *payload, unsigned short dscp, u8 prio)
+{
+	mlxsw_reg_qpdpm_dscp_entry_e_set(payload, dscp, 1);
+	mlxsw_reg_qpdpm_dscp_entry_prio_set(payload, dscp, prio);
+}
+
 /* PMLP - Ports Module to Local Port Register
  * ------------------------------------------
  * Configures the assignment of modules to local ports.
@@ -8539,9 +8754,13 @@ static const struct mlxsw_reg_info *mlxsw_reg_infos[] = {
 	MLXSW_REG(percr),
 	MLXSW_REG(pererp),
 	MLXSW_REG(iedr),
+	MLXSW_REG(qpts),
 	MLXSW_REG(qpcr),
 	MLXSW_REG(qtct),
 	MLXSW_REG(qeec),
+	MLXSW_REG(qrwe),
+	MLXSW_REG(qpdsm),
+	MLXSW_REG(qpdpm),
 	MLXSW_REG(pmlp),
 	MLXSW_REG(pmtu),
 	MLXSW_REG(ptys),
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum.h b/drivers/net/ethernet/mellanox/mlxsw/spectrum.h
index bc2704193666..13eca1a79d52 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum.h
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum.h
@@ -1,6 +1,6 @@
 /*
  * drivers/net/ethernet/mellanox/mlxsw/spectrum.h
- * Copyright (c) 2015-2017 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2015-2018 Mellanox Technologies. All rights reserved.
  * Copyright (c) 2015-2017 Jiri Pirko <jiri@mellanox.com>
  * Copyright (c) 2015 Ido Schimmel <idosch@mellanox.com>
  * Copyright (c) 2015 Elad Raz <eladr@mellanox.com>
@@ -54,6 +54,7 @@
 #include "core.h"
 #include "core_acl_flex_keys.h"
 #include "core_acl_flex_actions.h"
+#include "reg.h"
 
 #define MLXSW_SP_FID_8021D_MAX 1024
 
@@ -243,6 +244,7 @@ struct mlxsw_sp_port {
 		struct ieee_ets *ets;
 		struct ieee_maxrate *maxrate;
 		struct ieee_pfc *pfc;
+		enum mlxsw_reg_qpts_trust_state trust_state;
 	} dcb;
 	struct {
 		u8 module;
diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_dcb.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_dcb.c
index b6ed7f7c531e..c31aeb25ab5a 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_dcb.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_dcb.c
@@ -1,6 +1,6 @@
 /*
  * drivers/net/ethernet/mellanox/mlxsw/spectrum_dcb.c
- * Copyright (c) 2016 Mellanox Technologies. All rights reserved.
+ * Copyright (c) 2016-2018 Mellanox Technologies. All rights reserved.
  * Copyright (c) 2016 Ido Schimmel <idosch@mellanox.com>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -255,6 +255,270 @@ static int mlxsw_sp_dcbnl_ieee_setets(struct net_device *dev,
 	return 0;
 }
 
+static int mlxsw_sp_dcbnl_app_validate(struct net_device *dev,
+				       struct dcb_app *app)
+{
+	int prio;
+
+	if (app->priority >= IEEE_8021QAZ_MAX_TCS) {
+		netdev_err(dev, "APP entry with priority value %u is invalid\n",
+			   app->priority);
+		return -EINVAL;
+	}
+
+	switch (app->selector) {
+	case IEEE_8021QAZ_APP_SEL_DSCP:
+		if (app->protocol >= 64) {
+			netdev_err(dev, "DSCP APP entry with protocol value %u is invalid\n",
+				   app->protocol);
+			return -EINVAL;
+		}
+
+		/* Warn about any DSCP APP entries with the same PID. */
+		prio = fls(dcb_ieee_getapp_mask(dev, app));
+		if (prio--) {
+			if (prio < app->priority)
+				netdev_warn(dev, "Choosing priority %d for DSCP %d in favor of previously-active value of %d\n",
+					    app->priority, app->protocol, prio);
+			else if (prio > app->priority)
+				netdev_warn(dev, "Ignoring new priority %d for DSCP %d in favor of current value of %d\n",
+					    app->priority, app->protocol, prio);
+		}
+		break;
+
+	case IEEE_8021QAZ_APP_SEL_ETHERTYPE:
+		if (app->protocol) {
+			netdev_err(dev, "EtherType APP entries with protocol value != 0 not supported\n");
+			return -EINVAL;
+		}
+		break;
+
+	default:
+		netdev_err(dev, "APP entries with selector %u not supported\n",
+			   app->selector);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static u8
+mlxsw_sp_port_dcb_app_default_prio(struct mlxsw_sp_port *mlxsw_sp_port)
+{
+	u8 prio_mask;
+
+	prio_mask = dcb_ieee_getapp_default_prio_mask(mlxsw_sp_port->dev);
+	if (prio_mask)
+		/* Take the highest configured priority. */
+		return fls(prio_mask) - 1;
+
+	return 0;
+}
+
+static void
+mlxsw_sp_port_dcb_app_dscp_prio_map(struct mlxsw_sp_port *mlxsw_sp_port,
+				    u8 default_prio,
+				    struct dcb_ieee_app_dscp_map *map)
+{
+	int i;
+
+	dcb_ieee_getapp_dscp_prio_mask_map(mlxsw_sp_port->dev, map);
+	for (i = 0; i < ARRAY_SIZE(map->map); ++i) {
+		if (map->map[i])
+			map->map[i] = fls(map->map[i]) - 1;
+		else
+			map->map[i] = default_prio;
+	}
+}
+
+static bool
+mlxsw_sp_port_dcb_app_prio_dscp_map(struct mlxsw_sp_port *mlxsw_sp_port,
+				    struct dcb_ieee_app_prio_map *map)
+{
+	bool have_dscp = false;
+	int i;
+
+	dcb_ieee_getapp_prio_dscp_mask_map(mlxsw_sp_port->dev, map);
+	for (i = 0; i < ARRAY_SIZE(map->map); ++i) {
+		if (map->map[i]) {
+			map->map[i] = fls64(map->map[i]) - 1;
+			have_dscp = true;
+		}
+	}
+
+	return have_dscp;
+}
+
+static int
+mlxsw_sp_port_dcb_app_update_qpts(struct mlxsw_sp_port *mlxsw_sp_port,
+				  enum mlxsw_reg_qpts_trust_state ts)
+{
+	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
+	char qpts_pl[MLXSW_REG_QPTS_LEN];
+
+	mlxsw_reg_qpts_pack(qpts_pl, mlxsw_sp_port->local_port, ts);
+	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(qpts), qpts_pl);
+}
+
+static int
+mlxsw_sp_port_dcb_app_update_qrwe(struct mlxsw_sp_port *mlxsw_sp_port,
+				  bool rewrite_dscp)
+{
+	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
+	char qrwe_pl[MLXSW_REG_QRWE_LEN];
+
+	mlxsw_reg_qrwe_pack(qrwe_pl, mlxsw_sp_port->local_port,
+			    false, rewrite_dscp);
+	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(qrwe), qrwe_pl);
+}
+
+static int
+mlxsw_sp_port_dcb_toggle_trust(struct mlxsw_sp_port *mlxsw_sp_port,
+			       enum mlxsw_reg_qpts_trust_state ts)
+{
+	bool rewrite_dscp = ts == MLXSW_REG_QPTS_TRUST_STATE_DSCP;
+	int err;
+
+	if (mlxsw_sp_port->dcb.trust_state == ts)
+		return 0;
+
+	err = mlxsw_sp_port_dcb_app_update_qpts(mlxsw_sp_port, ts);
+	if (err)
+		return err;
+
+	err = mlxsw_sp_port_dcb_app_update_qrwe(mlxsw_sp_port, rewrite_dscp);
+	if (err)
+		goto err_update_qrwe;
+
+	mlxsw_sp_port->dcb.trust_state = ts;
+	return 0;
+
+err_update_qrwe:
+	mlxsw_sp_port_dcb_app_update_qpts(mlxsw_sp_port,
+					  mlxsw_sp_port->dcb.trust_state);
+	return err;
+}
+
+static int
+mlxsw_sp_port_dcb_app_update_qpdpm(struct mlxsw_sp_port *mlxsw_sp_port,
+				   struct dcb_ieee_app_dscp_map *map)
+{
+	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
+	char qpdpm_pl[MLXSW_REG_QPDPM_LEN];
+	short int i;
+
+	mlxsw_reg_qpdpm_pack(qpdpm_pl, mlxsw_sp_port->local_port);
+	for (i = 0; i < ARRAY_SIZE(map->map); ++i)
+		mlxsw_reg_qpdpm_dscp_pack(qpdpm_pl, i, map->map[i]);
+	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(qpdpm), qpdpm_pl);
+}
+
+static int
+mlxsw_sp_port_dcb_app_update_qpdsm(struct mlxsw_sp_port *mlxsw_sp_port,
+				   struct dcb_ieee_app_prio_map *map)
+{
+	struct mlxsw_sp *mlxsw_sp = mlxsw_sp_port->mlxsw_sp;
+	char qpdsm_pl[MLXSW_REG_QPDSM_LEN];
+	short int i;
+
+	mlxsw_reg_qpdsm_pack(qpdsm_pl, mlxsw_sp_port->local_port);
+	for (i = 0; i < ARRAY_SIZE(map->map); ++i)
+		mlxsw_reg_qpdsm_prio_pack(qpdsm_pl, i, map->map[i]);
+	return mlxsw_reg_write(mlxsw_sp->core, MLXSW_REG(qpdsm), qpdsm_pl);
+}
+
+static int mlxsw_sp_port_dcb_app_update(struct mlxsw_sp_port *mlxsw_sp_port)
+{
+	struct dcb_ieee_app_prio_map prio_map;
+	struct dcb_ieee_app_dscp_map dscp_map;
+	u8 default_prio;
+	bool have_dscp;
+	int err;
+
+	default_prio = mlxsw_sp_port_dcb_app_default_prio(mlxsw_sp_port);
+	have_dscp = mlxsw_sp_port_dcb_app_prio_dscp_map(mlxsw_sp_port,
+							&prio_map);
+
+	if (!have_dscp) {
+		err = mlxsw_sp_port_dcb_toggle_trust(mlxsw_sp_port,
+					MLXSW_REG_QPTS_TRUST_STATE_PCP);
+		if (err)
+			netdev_err(mlxsw_sp_port->dev, "Couldn't switch to trust L2\n");
+		return err;
+	}
+
+	mlxsw_sp_port_dcb_app_dscp_prio_map(mlxsw_sp_port, default_prio,
+					    &dscp_map);
+	err = mlxsw_sp_port_dcb_app_update_qpdpm(mlxsw_sp_port,
+						 &dscp_map);
+	if (err) {
+		netdev_err(mlxsw_sp_port->dev, "Couldn't configure priority map\n");
+		return err;
+	}
+
+	err = mlxsw_sp_port_dcb_app_update_qpdsm(mlxsw_sp_port,
+						 &prio_map);
+	if (err) {
+		netdev_err(mlxsw_sp_port->dev, "Couldn't configure DSCP rewrite map\n");
+		return err;
+	}
+
+	err = mlxsw_sp_port_dcb_toggle_trust(mlxsw_sp_port,
+					     MLXSW_REG_QPTS_TRUST_STATE_DSCP);
+	if (err) {
+		/* A failure to set trust DSCP means that the QPDPM and QPDSM
+		 * maps installed above are not in effect. And since we are here
+		 * attempting to set trust DSCP, we couldn't have attempted to
+		 * switch trust to PCP. Thus no cleanup is necessary.
+		 */
+		netdev_err(mlxsw_sp_port->dev, "Couldn't switch to trust L3\n");
+		return err;
+	}
+
+	return 0;
+}
+
+static int mlxsw_sp_dcbnl_ieee_setapp(struct net_device *dev,
+				      struct dcb_app *app)
+{
+	struct mlxsw_sp_port *mlxsw_sp_port = netdev_priv(dev);
+	int err;
+
+	err = mlxsw_sp_dcbnl_app_validate(dev, app);
+	if (err)
+		return err;
+
+	err = dcb_ieee_setapp(dev, app);
+	if (err)
+		return err;
+
+	err = mlxsw_sp_port_dcb_app_update(mlxsw_sp_port);
+	if (err)
+		goto err_update;
+
+	return 0;
+
+err_update:
+	dcb_ieee_delapp(dev, app);
+	return err;
+}
+
+static int mlxsw_sp_dcbnl_ieee_delapp(struct net_device *dev,
+				      struct dcb_app *app)
+{
+	struct mlxsw_sp_port *mlxsw_sp_port = netdev_priv(dev);
+	int err;
+
+	err = dcb_ieee_delapp(dev, app);
+	if (err)
+		return err;
+
+	err = mlxsw_sp_port_dcb_app_update(mlxsw_sp_port);
+	if (err)
+		netdev_err(dev, "Failed to update DCB APP configuration\n");
+	return 0;
+}
+
 static int mlxsw_sp_dcbnl_ieee_getmaxrate(struct net_device *dev,
 					  struct ieee_maxrate *maxrate)
 {
@@ -394,6 +658,8 @@ static const struct dcbnl_rtnl_ops mlxsw_sp_dcbnl_ops = {
 	.ieee_setmaxrate	= mlxsw_sp_dcbnl_ieee_setmaxrate,
 	.ieee_getpfc		= mlxsw_sp_dcbnl_ieee_getpfc,
 	.ieee_setpfc		= mlxsw_sp_dcbnl_ieee_setpfc,
+	.ieee_setapp		= mlxsw_sp_dcbnl_ieee_setapp,
+	.ieee_delapp		= mlxsw_sp_dcbnl_ieee_delapp,
 
 	.getdcbx		= mlxsw_sp_dcbnl_getdcbx,
 	.setdcbx		= mlxsw_sp_dcbnl_setdcbx,
@@ -467,6 +733,7 @@ int mlxsw_sp_port_dcb_init(struct mlxsw_sp_port *mlxsw_sp_port)
 	if (err)
 		goto err_port_pfc_init;
 
+	mlxsw_sp_port->dcb.trust_state = MLXSW_REG_QPTS_TRUST_STATE_PCP;
 	mlxsw_sp_port->dev->dcbnl_ops = &mlxsw_sp_dcbnl_ops;
 
 	return 0;
diff --git a/include/net/dcbnl.h b/include/net/dcbnl.h
index 0e5e91be2d30..e22a8a3c089b 100644
--- a/include/net/dcbnl.h
+++ b/include/net/dcbnl.h
@@ -34,6 +34,19 @@ int dcb_ieee_setapp(struct net_device *, struct dcb_app *);
 int dcb_ieee_delapp(struct net_device *, struct dcb_app *);
 u8 dcb_ieee_getapp_mask(struct net_device *, struct dcb_app *);
 
+struct dcb_ieee_app_prio_map {
+	u64 map[IEEE_8021QAZ_MAX_TCS];
+};
+void dcb_ieee_getapp_prio_dscp_mask_map(const struct net_device *dev,
+					struct dcb_ieee_app_prio_map *p_map);
+
+struct dcb_ieee_app_dscp_map {
+	u8 map[64];
+};
+void dcb_ieee_getapp_dscp_prio_mask_map(const struct net_device *dev,
+					struct dcb_ieee_app_dscp_map *p_map);
+u8 dcb_ieee_getapp_default_prio_mask(const struct net_device *dev);
+
 int dcbnl_ieee_notify(struct net_device *dev, int event, int cmd,
 		      u32 seq, u32 pid);
 int dcbnl_cee_notify(struct net_device *dev, int event, int cmd,
diff --git a/net/dcb/dcbnl.c b/net/dcb/dcbnl.c
index 2589a6b78aa1..a556cd708885 100644
--- a/net/dcb/dcbnl.c
+++ b/net/dcb/dcbnl.c
@@ -1786,7 +1786,7 @@ static struct dcb_app_type *dcb_app_lookup(const struct dcb_app *app,
 		if (itr->app.selector == app->selector &&
 		    itr->app.protocol == app->protocol &&
 		    itr->ifindex == ifindex &&
-		    (!prio || itr->app.priority == prio))
+		    ((prio == -1) || itr->app.priority == prio))
 			return itr;
 	}
 
@@ -1821,7 +1821,8 @@ u8 dcb_getapp(struct net_device *dev, struct dcb_app *app)
 	u8 prio = 0;
 
 	spin_lock_bh(&dcb_lock);
-	if ((itr = dcb_app_lookup(app, dev->ifindex, 0)))
+	itr = dcb_app_lookup(app, dev->ifindex, -1);
+	if (itr)
 		prio = itr->app.priority;
 	spin_unlock_bh(&dcb_lock);
 
@@ -1849,7 +1850,8 @@ int dcb_setapp(struct net_device *dev, struct dcb_app *new)
 
 	spin_lock_bh(&dcb_lock);
 	/* Search for existing match and replace */
-	if ((itr = dcb_app_lookup(new, dev->ifindex, 0))) {
+	itr = dcb_app_lookup(new, dev->ifindex, -1);
+	if (itr) {
 		if (new->priority)
 			itr->app.priority = new->priority;
 		else {
@@ -1882,7 +1884,8 @@ u8 dcb_ieee_getapp_mask(struct net_device *dev, struct dcb_app *app)
 	u8 prio = 0;
 
 	spin_lock_bh(&dcb_lock);
-	if ((itr = dcb_app_lookup(app, dev->ifindex, 0)))
+	itr = dcb_app_lookup(app, dev->ifindex, -1);
+	if (itr)
 		prio |= 1 << itr->app.priority;
 	spin_unlock_bh(&dcb_lock);
 
@@ -1955,6 +1958,92 @@ int dcb_ieee_delapp(struct net_device *dev, struct dcb_app *del)
 }
 EXPORT_SYMBOL(dcb_ieee_delapp);
 
+/**
+ * dcb_ieee_getapp_prio_dscp_mask_map - For a given device, find mapping from
+ * priorities to the DSCP values assigned to that priority. Initialize p_map
+ * such that each map element holds a bit mask of DSCP values configured for
+ * that priority by APP entries.
+ */
+void dcb_ieee_getapp_prio_dscp_mask_map(const struct net_device *dev,
+					struct dcb_ieee_app_prio_map *p_map)
+{
+	int ifindex = dev->ifindex;
+	struct dcb_app_type *itr;
+	u8 prio;
+
+	memset(p_map->map, 0, sizeof(p_map->map));
+
+	spin_lock_bh(&dcb_lock);
+	list_for_each_entry(itr, &dcb_app_list, list) {
+		if (itr->ifindex == ifindex &&
+		    itr->app.selector == IEEE_8021QAZ_APP_SEL_DSCP &&
+		    itr->app.protocol < 64 &&
+		    itr->app.priority < IEEE_8021QAZ_MAX_TCS) {
+			prio = itr->app.priority;
+			p_map->map[prio] |= 1ULL << itr->app.protocol;
+		}
+	}
+	spin_unlock_bh(&dcb_lock);
+}
+EXPORT_SYMBOL(dcb_ieee_getapp_prio_dscp_mask_map);
+
+/**
+ * dcb_ieee_getapp_dscp_prio_mask_map - For a given device, find mapping from
+ * DSCP values to the priorities assigned to that DSCP value. Initialize p_map
+ * such that each map element holds a bit mask of priorities configured for a
+ * given DSCP value by APP entries.
+ */
+void
+dcb_ieee_getapp_dscp_prio_mask_map(const struct net_device *dev,
+				   struct dcb_ieee_app_dscp_map *p_map)
+{
+	int ifindex = dev->ifindex;
+	struct dcb_app_type *itr;
+
+	memset(p_map->map, 0, sizeof(p_map->map));
+
+	spin_lock_bh(&dcb_lock);
+	list_for_each_entry(itr, &dcb_app_list, list) {
+		if (itr->ifindex == ifindex &&
+		    itr->app.selector == IEEE_8021QAZ_APP_SEL_DSCP &&
+		    itr->app.protocol < 64 &&
+		    itr->app.priority < IEEE_8021QAZ_MAX_TCS)
+			p_map->map[itr->app.protocol] |= 1 << itr->app.priority;
+	}
+	spin_unlock_bh(&dcb_lock);
+}
+EXPORT_SYMBOL(dcb_ieee_getapp_dscp_prio_mask_map);
+
+/**
+ * Per 802.1Q-2014, the selector value of 1 is used for matching on Ethernet
+ * type, with valid PID values >= 1536. A special meaning is then assigned to
+ * protocol value of 0: "default priority. For use when priority is not
+ * otherwise specified".
+ *
+ * dcb_ieee_getapp_default_prio_mask - For a given device, find all APP entries
+ * of the form {$PRIO, ETHERTYPE, 0} and construct a bit mask of all default
+ * priorities set by these entries.
+ */
+u8 dcb_ieee_getapp_default_prio_mask(const struct net_device *dev)
+{
+	int ifindex = dev->ifindex;
+	struct dcb_app_type *itr;
+	u8 mask = 0;
+
+	spin_lock_bh(&dcb_lock);
+	list_for_each_entry(itr, &dcb_app_list, list) {
+		if (itr->ifindex == ifindex &&
+		    itr->app.selector == IEEE_8021QAZ_APP_SEL_ETHERTYPE &&
+		    itr->app.protocol == 0 &&
+		    itr->app.priority < IEEE_8021QAZ_MAX_TCS)
+			mask |= 1 << itr->app.priority;
+	}
+	spin_unlock_bh(&dcb_lock);
+
+	return mask;
+}
+EXPORT_SYMBOL(dcb_ieee_getapp_default_prio_mask);
+
 static int __init dcbnl_init(void)
 {
 	INIT_LIST_HEAD(&dcb_app_list);
diff --git a/tools/testing/selftests/drivers/net/mlxsw/qos_dscp_bridge.sh b/tools/testing/selftests/drivers/net/mlxsw/qos_dscp_bridge.sh
new file mode 100755
index 000000000000..418319f19108
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/mlxsw/qos_dscp_bridge.sh
@@ -0,0 +1,248 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# Test for DSCP prioritization and rewrite. Packets ingress $swp1 with a DSCP
+# tag and are prioritized according to the map at $swp1. They egress $swp2 and
+# the DSCP value is updated to match the map at that interface. The updated DSCP
+# tag is verified at $h2.
+#
+# ICMP responses are produced with the same DSCP tag that arrived at $h2. They
+# go through prioritization at $swp2 and DSCP retagging at $swp1. The tag is
+# verified at $h1--it should match the original tag.
+#
+# +----------------------+                             +----------------------+
+# | H1                   |                             |                   H2 |
+# |    + $h1             |                             |            $h2 +     |
+# |    | 192.0.2.1/28    |                             |   192.0.2.2/28 |     |
+# +----|-----------------+                             +----------------|-----+
+#      |                                                                |
+# +----|----------------------------------------------------------------|-----+
+# | SW |                                                                |     |
+# |  +-|----------------------------------------------------------------|-+   |
+# |  | + $swp1                       BR                           $swp2 + |   |
+# |  |   APP=0,5,10 .. 7,5,17                      APP=0,5,20 .. 7,5,27   |   |
+# |  +--------------------------------------------------------------------+   |
+# +---------------------------------------------------------------------------+
+
+ALL_TESTS="
+	ping_ipv4
+	test_dscp
+"
+
+lib_dir=$(dirname $0)/../../../net/forwarding
+
+NUM_NETIFS=4
+source $lib_dir/lib.sh
+
+__dscp_capture_add_del()
+{
+	local add_del=$1; shift
+	local dev=$1; shift
+	local base=$1; shift
+	local dscp;
+
+	for prio in {0..7}; do
+		dscp=$((base + prio))
+		__icmp_capture_add_del $add_del $dscp "" $dev \
+				       "ip_tos $((dscp << 2))"
+	done
+}
+
+dscp_capture_install()
+{
+	local dev=$1; shift
+	local base=$1; shift
+
+	__dscp_capture_add_del add $dev $base
+}
+
+dscp_capture_uninstall()
+{
+	local dev=$1; shift
+	local base=$1; shift
+
+	__dscp_capture_add_del del $dev $base
+}
+
+h1_create()
+{
+	local dscp;
+
+	simple_if_init $h1 192.0.2.1/28
+	tc qdisc add dev $h1 clsact
+	dscp_capture_install $h1 10
+}
+
+h1_destroy()
+{
+	dscp_capture_uninstall $h1 10
+	tc qdisc del dev $h1 clsact
+	simple_if_fini $h1 192.0.2.1/28
+}
+
+h2_create()
+{
+	simple_if_init $h2 192.0.2.2/28
+	tc qdisc add dev $h2 clsact
+	dscp_capture_install $h2 20
+}
+
+h2_destroy()
+{
+	dscp_capture_uninstall $h2 20
+	tc qdisc del dev $h2 clsact
+	simple_if_fini $h2 192.0.2.2/28
+}
+
+dscp_map()
+{
+	local base=$1; shift
+
+	for prio in {0..7}; do
+		echo app=$prio,5,$((base + prio))
+	done
+}
+
+lldpad_wait()
+{
+	local dev=$1; shift
+
+	while lldptool -t -i $dev -V APP -c app | grep -q pending; do
+	    echo "$dev: waiting for lldpad to push pending APP updates"
+	    sleep 5
+	done
+}
+
+switch_create()
+{
+	ip link add name br1 type bridge vlan_filtering 1
+	ip link set dev br1 up
+	ip link set dev $swp1 master br1
+	ip link set dev $swp1 up
+	ip link set dev $swp2 master br1
+	ip link set dev $swp2 up
+
+	lldptool -T -i $swp1 -V APP $(dscp_map 10) >/dev/null
+	lldptool -T -i $swp2 -V APP $(dscp_map 20) >/dev/null
+	lldpad_wait $swp1
+	lldpad_wait $swp2
+}
+
+switch_destroy()
+{
+	lldptool -T -i $swp2 -V APP -d $(dscp_map 20) >/dev/null
+	lldptool -T -i $swp1 -V APP -d $(dscp_map 10) >/dev/null
+
+	# Give lldpad a chance to push down the changes. If the device is downed
+	# too soon, the updates will be left pending, but will have been struck
+	# off the lldpad's DB already, and we won't be able to tell. Then on
+	# next test iteration this would cause weirdness as newly-added APP
+	# rules conflict with the old ones, sometimes getting stuck in an
+	# "unknown" state.
+	sleep 5
+
+	ip link set dev $swp2 nomaster
+	ip link set dev $swp1 nomaster
+	ip link del dev br1
+}
+
+setup_prepare()
+{
+	h1=${NETIFS[p1]}
+	swp1=${NETIFS[p2]}
+
+	swp2=${NETIFS[p3]}
+	h2=${NETIFS[p4]}
+
+	vrf_prepare
+
+	h1_create
+	h2_create
+	switch_create
+}
+
+cleanup()
+{
+	pre_cleanup
+
+	switch_destroy
+	h2_destroy
+	h1_destroy
+
+	vrf_cleanup
+}
+
+dscp_fetch_stats()
+{
+	local dev=$1; shift
+	local base=$1; shift
+
+	for prio in {0..7}; do
+		local dscp=$((base + prio))
+		local t=$(tc_rule_stats_get $dev $dscp)
+		echo "[$dscp]=$t "
+	done
+}
+
+ping_ipv4()
+{
+	ping_test $h1 192.0.2.2
+}
+
+dscp_ping_test()
+{
+	local vrf_name=$1; shift
+	local sip=$1; shift
+	local dip=$1; shift
+	local prio=$1; shift
+	local dev_10=$1; shift
+	local dev_20=$1; shift
+
+	local dscp_10=$(((prio + 10) << 2))
+	local dscp_20=$(((prio + 20) << 2))
+
+	RET=0
+
+	local -A t0s
+	eval "t0s=($(dscp_fetch_stats $dev_10 10)
+		   $(dscp_fetch_stats $dev_20 20))"
+
+	ip vrf exec $vrf_name \
+	   ${PING} -Q $dscp_10 ${sip:+-I $sip} $dip \
+		   -c 10 -i 0.1 -w 2 &> /dev/null
+
+	local -A t1s
+	eval "t1s=($(dscp_fetch_stats $dev_10 10)
+		   $(dscp_fetch_stats $dev_20 20))"
+
+	for key in ${!t0s[@]}; do
+		local expect
+		if ((key == dscp_10 || key == dscp_20)); then
+			expect=10
+		else
+			expect=0
+		fi
+
+		local delta=$((t1s[key] - t0s[key]))
+		((expect == delta))
+		check_err $? "DSCP $key: Expected to capture $expect packets, got $delta."
+	done
+
+	log_test "DSCP rewrite: $dscp_10-(prio $prio)-$dscp_20"
+}
+
+test_dscp()
+{
+	for prio in {0..7}; do
+		dscp_ping_test v$h1 192.0.2.1 192.0.2.2 $prio $h1 $h2
+	done
+}
+
+trap cleanup EXIT
+
+setup_prepare
+setup_wait
+
+tests_run
+
+exit $EXIT_STATUS