Message-Id: <1593516846-28189-1-git-send-email-vasundhara-v.volam@broadcom.com>
Date:   Tue, 30 Jun 2020 17:04:06 +0530
From:   Vasundhara Volam <vasundhara-v.volam@...adcom.com>
To:     davem@...emloft.net, netdev@...r.kernel.org
Cc:     michael.chan@...adcom.com, kuba@...nel.org, jiri@...lanox.com,
        jiri@...nulli.us, mkubecek@...e.cz,
        Vasundhara Volam <vasundhara-v.volam@...adcom.com>
Subject: [RFC v2 net-next] devlink: Add reset subcommand.

Advanced NICs support live reset of some of the hardware
components, that resets the device immediately with all the
host drivers loaded.

Add devlink reset subcommand to support live and deferred modes
of reset. It allows to reset the hardware components of the
entire device and supports the following fields:

component:
----------
1. MGMT : Management processor.
2. DMA : DMA engine.
3. RAM : RAM shared between multiple components.
4. AP : Application processor.
5. ROCE : RoCE management processor.
6. All : All possible components.

Drivers are allowed to reset only a subset of requested components.

width:
------
1. single - single host.
2. multi  - Multi host.

mode:
-----
1. deferred - Reset will happen after unloading all the host drivers
              on the device. This is be default reset type, if user
              does not specify the type.
2. live - Reset will happen immediately with all host drivers loaded
          in real time. If the live reset is not supported, driver
          will return the error.

This patch is a proposal in continuation to discussion to the
following thread:

"[PATCH v3 net-next 0/6] bnxt_en: Add 'enable_live_dev_reset' and 'allow_live_dev_reset' generic devlink params."

and here is the URL to the patch series:

https://patchwork.ozlabs.org/project/netdev/list/?series=180426&state=*

If the proposal looks good, I will re-send the whole patchset
including devlink changes and driver usage.

Signed-off-by: Vasundhara Volam <vasundhara-v.volam@...adcom.com>
Reviewed-by: Michael Chan <michael.chan@...adcom.com>
---
v2:
- Switch RAM and AP component definitions.
- Remove IRQ, FILTER, OFFLOAD, MAC, PHY components as they are port
specific components.
- Rename function to host in width parameter.
---
 Documentation/networking/devlink/devlink-reset.rst | 50 +++++++++++++
 include/net/devlink.h                              |  2 +
 include/uapi/linux/devlink.h                       | 46 ++++++++++++
 net/core/devlink.c                                 | 85 ++++++++++++++++++++++
 4 files changed, 183 insertions(+)
 create mode 100644 Documentation/networking/devlink/devlink-reset.rst

diff --git a/Documentation/networking/devlink/devlink-reset.rst b/Documentation/networking/devlink/devlink-reset.rst
new file mode 100644
index 0000000..652800d
--- /dev/null
+++ b/Documentation/networking/devlink/devlink-reset.rst
@@ -0,0 +1,50 @@
+.. SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+
+.. _devlink_reset:
+
+=============
+Devlink reset
+=============
+
+The ``devlink-reset`` API allows reset the hardware components of the device. After the reset,
+device loads the pending updated firmware image.
+Example use::
+
+  $ devlink dev reset pci/0000:05:00.0 components COMPONENTS
+
+Note that user can mention multiple components.
+
+================
+Reset components
+================
+
+List of available components::
+
+``DEVLINK_RESET_COMP_MGMT`` - Management processor.
+``DEVLINK_RESET_COMP_DMA`` - DMA engine.
+``DEVLINK_RESET_COMP_RAM`` - RAM shared between multiple components.
+``DEVLINK_RESET_COMP_AP``   - Application processor.
+``DEVLINK_RESET_COMP_ROCE`` - RoCE management processor.
+``DEVLINK_RESET_COMP_ALL``  - All components.
+
+===========
+Reset width
+===========
+
+List of available widths::
+
+``DEVLINK_RESET_WIDTH_SINGLE`` - Device is used by single dedicated host.
+``DEVLINK_RESET_WIDTH_MULTI``  - Device is shared across multiple hosts.
+
+Note that if user specifies DEVLINK_RESET_WIDTH_SINGLE in a multi-host environment, driver returns
+error if it does not support resetting a single host.
+
+===========
+Reset modes
+===========
+
+List of available reset modes::
+
+``DEVLINK_RESET_MODE_DEFERRED``  - Reset happens after all host drivers are unloaded on the device.
+``DEVLINK_RESET_MODE_LIVE``      - Reset happens immediately, with all loaded host drivers in real
+                                   time.
diff --git a/include/net/devlink.h b/include/net/devlink.h
index 428f55f..a71c8f5 100644
--- a/include/net/devlink.h
+++ b/include/net/devlink.h
@@ -1129,6 +1129,8 @@ struct devlink_ops {
 	int (*port_function_hw_addr_set)(struct devlink *devlink, struct devlink_port *port,
 					 const u8 *hw_addr, int hw_addr_len,
 					 struct netlink_ext_ack *extack);
+	int (*reset)(struct devlink *devlink, u32 *components, u8 width, u8 mode,
+		     struct netlink_ext_ack *extack);
 };
 
 static inline void *devlink_priv(struct devlink *devlink)
diff --git a/include/uapi/linux/devlink.h b/include/uapi/linux/devlink.h
index 87c83a8..6f32c00 100644
--- a/include/uapi/linux/devlink.h
+++ b/include/uapi/linux/devlink.h
@@ -122,6 +122,9 @@ enum devlink_command {
 	DEVLINK_CMD_TRAP_POLICER_NEW,
 	DEVLINK_CMD_TRAP_POLICER_DEL,
 
+	DEVLINK_CMD_RESET,
+	DEVLINK_CMD_RESET_STATUS,	/* notification only */
+
 	/* add new commands above here */
 	__DEVLINK_CMD_MAX,
 	DEVLINK_CMD_MAX = __DEVLINK_CMD_MAX - 1
@@ -265,6 +268,44 @@ enum devlink_trap_type {
 	DEVLINK_TRAP_TYPE_CONTROL,
 };
 
+/**
+ * enum devlink_reset_component - Reset components.
+ * @DEVLINK_RESET_COMP_MGMT: Management processor.
+ * @DEVLINK_RESET_COMP_DMA: DMA engine.
+ * @DEVLINK_RESET_COMP_RAM: RAM shared between multiple components.
+ * @DEVLINK_RESET_COMP_AP: Application processor.
+ * @DEVLINK_RESET_COMP_ROCE: RoCE management processor.
+ * @DEVLINK_RESET_COMP_ALL: All components.
+ */
+enum devlink_reset_component {
+	DEVLINK_RESET_COMP_MGMT		= (1 << 0),
+	DEVLINK_RESET_COMP_DMA		= (1 << 1),
+	DEVLINK_RESET_COMP_RAM		= (1 << 2),
+	DEVLINK_RESET_COMP_AP		= (1 << 3),
+	DEVLINK_RESET_COMP_ROCE		= (1 << 4),
+	DEVLINK_RESET_COMP_ALL		= 0xffffffff,
+};
+
+/**
+ * enum devlink_reset_width - Number of hosts effected by reset.
+ * @DEVLINK_RESET_WIDTH_SINGLE: Device is used by single dedicated host.
+ * @DEVLINK_RESET_WIDTH_MULTI: Device is shared across multiple hosts.
+ */
+enum devlink_reset_width {
+	DEVLINK_RESET_WIDTH_SINGLE	= 0,
+	DEVLINK_RESET_WIDTH_MULTI	= 1,
+};
+
+/**
+ * enum devlink_reset_mode - Modes of reset.
+ * @DEVLINK_RESET_MODE_DEFERRED: Reset will happen after host drivers are unloaded.
+ * @DEVLINK_RESET_MODE_LIVE: All host drivers also will be reset without reloading manually.
+ */
+enum devlink_reset_mode {
+	DEVLINK_RESET_MODE_DEFERRED	= 0,
+	DEVLINK_RESET_MODE_LIVE		= 1,
+};
+
 enum {
 	/* Trap can report input port as metadata */
 	DEVLINK_ATTR_TRAP_METADATA_TYPE_IN_PORT,
@@ -455,6 +496,11 @@ enum devlink_attr {
 
 	DEVLINK_ATTR_INFO_BOARD_SERIAL_NUMBER,	/* string */
 
+	DEVLINK_ATTR_RESET_COMPONENTS,		/* u32 */
+	DEVLINK_ATTR_RESET_WIDTH,		/* u8 */
+	DEVLINK_ATTR_RESET_MODE,		/* u8 */
+	DEVLINK_ATTR_RESET_STATUS_MSG,		/* string */
+
 	/* add new attributes above here, update the policy in devlink.c */
 
 	__DEVLINK_ATTR_MAX,
diff --git a/net/core/devlink.c b/net/core/devlink.c
index 6ae3680..c0eebc5 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -6797,6 +6797,82 @@ static int devlink_nl_cmd_trap_policer_set_doit(struct sk_buff *skb,
 	return devlink_trap_policer_set(devlink, policer_item, info);
 }
 
+static int devlink_nl_reset_fill(struct sk_buff *msg, struct devlink *devlink,
+				 const char *status_msg, u32 components)
+{
+	void *hdr;
+
+	hdr = genlmsg_put(msg, 0, 0, &devlink_nl_family, 0, DEVLINK_CMD_RESET_STATUS);
+	if (!hdr)
+		return -EMSGSIZE;
+
+	if (devlink_nl_put_handle(msg, devlink))
+		goto nla_put_failure;
+
+	if (status_msg && nla_put_string(msg, DEVLINK_ATTR_RESET_STATUS_MSG, status_msg))
+		goto nla_put_failure;
+
+	if (nla_put_u32(msg, DEVLINK_ATTR_RESET_COMPONENTS, components))
+		goto nla_put_failure;
+
+	genlmsg_end(msg, hdr);
+	return 0;
+
+nla_put_failure:
+	genlmsg_cancel(msg, hdr);
+	return -EMSGSIZE;
+}
+
+static void __devlink_reset_notify(struct devlink *devlink, const char *status_msg, u32 components)
+{
+	struct sk_buff *msg;
+	int err;
+
+	msg = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
+	if (!msg)
+		return;
+
+	err = devlink_nl_reset_fill(msg, devlink, status_msg, components);
+	if (err)
+		goto out;
+
+	genlmsg_multicast_netns(&devlink_nl_family, devlink_net(devlink), msg, 0,
+				DEVLINK_MCGRP_CONFIG, GFP_KERNEL);
+	return;
+
+out:
+	nlmsg_free(msg);
+}
+
+static int devlink_nl_cmd_reset(struct sk_buff *skb, struct genl_info *info)
+{
+	struct devlink *devlink = info->user_ptr[0];
+	u32 components, req_comps;
+	struct nlattr *nla_type;
+	u8 width, mode;
+	int err;
+
+	if (!devlink->ops->reset)
+		return -EOPNOTSUPP;
+
+	if (!info->attrs[DEVLINK_ATTR_RESET_COMPONENTS])
+		return -EINVAL;
+	components = nla_get_u32(info->attrs[DEVLINK_ATTR_RESET_COMPONENTS]);
+
+	nla_type = info->attrs[DEVLINK_ATTR_RESET_WIDTH];
+	width = nla_type ? nla_get_u8(nla_type) : DEVLINK_RESET_WIDTH_SINGLE;
+
+	nla_type = info->attrs[DEVLINK_ATTR_RESET_MODE];
+	mode = nla_type ? nla_get_u8(nla_type) : DEVLINK_RESET_MODE_DEFERRED;
+
+	req_comps = components;
+	__devlink_reset_notify(devlink, "Reset request", components);
+	err = devlink->ops->reset(devlink, &components, width, mode, info->extack);
+	__devlink_reset_notify(devlink, "Components reset", req_comps & ~components);
+
+	return err;
+}
+
 static const struct nla_policy devlink_nl_policy[DEVLINK_ATTR_MAX + 1] = {
 	[DEVLINK_ATTR_UNSPEC] = { .strict_start_type =
 		DEVLINK_ATTR_TRAP_POLICER_ID },
@@ -6842,6 +6918,9 @@ static int devlink_nl_cmd_trap_policer_set_doit(struct sk_buff *skb,
 	[DEVLINK_ATTR_TRAP_POLICER_RATE] = { .type = NLA_U64 },
 	[DEVLINK_ATTR_TRAP_POLICER_BURST] = { .type = NLA_U64 },
 	[DEVLINK_ATTR_PORT_FUNCTION] = { .type = NLA_NESTED },
+	[DEVLINK_ATTR_RESET_COMPONENTS] = { .type = NLA_U32 },
+	[DEVLINK_ATTR_RESET_WIDTH] = { .type = NLA_U8 },
+	[DEVLINK_ATTR_RESET_MODE] = { .type = NLA_U8 },
 };
 
 static const struct genl_ops devlink_nl_ops[] = {
@@ -7190,6 +7269,12 @@ static int devlink_nl_cmd_trap_policer_set_doit(struct sk_buff *skb,
 		.flags = GENL_ADMIN_PERM,
 		.internal_flags = DEVLINK_NL_FLAG_NEED_DEVLINK,
 	},
+	{
+		.cmd = DEVLINK_CMD_RESET,
+		.doit = devlink_nl_cmd_reset,
+		.flags = GENL_ADMIN_PERM,
+		.internal_flags = DEVLINK_NL_FLAG_NEED_DEVLINK,
+	},
 };
 
 static struct genl_family devlink_nl_family __ro_after_init = {
-- 
1.8.3.1

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