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Date:   Wed, 1 Jul 2020 07:51:44 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Vasundhara Volam <vasundhara-v.volam@...adcom.com>
Cc:     David Miller <davem@...emloft.net>,
        Netdev <netdev@...r.kernel.org>,
        Michael Chan <michael.chan@...adcom.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Jiri Pirko <jiri@...lanox.com>,
        Michal Kubecek <mkubecek@...e.cz>
Subject: Re: [RFC v2 net-next] devlink: Add reset subcommand.

Tue, Jun 30, 2020 at 05:15:18PM CEST, vasundhara-v.volam@...adcom.com wrote:
>On Tue, Jun 30, 2020 at 6:23 PM Jiri Pirko <jiri@...nulli.us> wrote:
>>
>> Tue, Jun 30, 2020 at 01:34:06PM CEST, vasundhara-v.volam@...adcom.com wrote:
>> >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.
>>
>> I don't understand why would user ever want to do this. He does not care
>> about some magic hw entities. He just expects the hw to work. I don't
>> undestand the purpose of exposing something like this. Could you please
>> explain in details? Thanks!
>>
>If a user requests multiple components and if the driver is only able
>to honor a subset, the driver will return the components unset which
>it is able to reset.  For example, if a user requests MGMT, RAM and
>ROCE components to be reset and driver resets only MGMT and ROCE.
>Driver will unset only MGMT and ROCE bits and notifies the user that
>RAM is not reset.
>
>This will be useful for drivers to reset only a subset of components
>requested instead of returning error or silently doing only a subset
>of components.
>
>Also, this will be helpful as user will not know the components
>supported by different vendors.

Your reply does not seem to be related to my question :/


>
>Thanks,
>Vasundhara
>
>>
>> >
>> >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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