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Date:   Wed, 1 Jul 2020 14:45:50 +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>,
        Moshe Shemesh <moshe@...lanox.com>
Subject: Re: [RFC v2 net-next] devlink: Add reset subcommand.

Wed, Jul 01, 2020 at 01:59:14PM CEST, vasundhara-v.volam@...adcom.com wrote:
>On Wed, Jul 1, 2020 at 3:17 PM Jiri Pirko <jiri@...nulli.us> wrote:
>>
>> Wed, Jul 01, 2020 at 11:25:50AM CEST, vasundhara-v.volam@...adcom.com wrote:
>> >On Wed, Jul 1, 2020 at 11:21 AM Jiri Pirko <jiri@...nulli.us> wrote:
>> >>
>> >> 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 :/
>> >I thought that you were referring to: "Drivers are allowed to reset
>> >only a subset of requested components."
>> >
>> >or were you referring to components? If yes, the user can select the
>> >components that he wants to go for reset. This will be useful in the
>> >case where, if the user flashed only a certain component and he wants
>> >to reset that particular component. For example, in the case of SOC
>> >there are 2 components: MGMT and AP. If a user flashes only
>> >application processor, he can choose to reset only application
>> >processor.
>>
>> We already have notion of "a component" in "devlink dev flash". I think
>> that the reset component name should be in-sync with the flash.
>Only 1 type of component "ETHTOOL_FLASH_ALL_REGIONS" is defined

I wonder why did you get impression I'm talking about ethtool. I'm not.
I'm talking about "devlink dev flash".


>currently. We can have same components for reset as well and extend as
>needed.
>>
>> Thinking about it a bit more, we can extend the flash command by "reset"
>> attribute that would indicate use wants to do flash&reset right away.
>This will remove the freedom of user to reset later after flashing.
>But I think it is fine.
>
>Also, I think adding reset attribute may complicate the flash command
>as we need more attributes for reset alone like width and mode.
>>
>> Also, thinking how this all aligns with "devlink dev reload" which we
>> currently have. The purpose of it is to re-instantiate driver instances,
>> but in case of mlxsw it means friggering FW reset as well.
>As I understand, "devlink dev reload" is to re-instantiate driver
>instances and will not be able to send firmware command to request a
>reset.

Well, it does.


>>
>> Moshe (cced) is now working on "devlink dev reload" extension that would
>> allow user to ask for a certain level of reload: driver instances only,
>> fw reset too, live fw patching, etc.
>>
>> Not sure how this overlaps with your intentions. I think it would be
>> great to see Moshe's RFC here as well so we can aligh the efforts.
>
>Sure, I will wait for RFC to get more idea.
>
>Thanks.
>>
>>
>> >
>> >>
>> >>
>> >> >
>> >> >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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