Date:   Tue, 26 May 2020 15:40:32 +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>, Jiri Pirko <jiri@...lanox.com>,
        Michael Chan <michael.chan@...adcom.com>
Subject: Re: [PATCH v2 net-next 1/4] devlink: Add new "allow_fw_live_reset"
 generic device parameter.

Tue, May 26, 2020 at 08:42:28AM CEST, vasundhara-v.volam@...adcom.com wrote:
>On Tue, May 26, 2020 at 10:17 AM Jiri Pirko <jiri@...nulli.us> wrote:
>>
>> Tue, May 26, 2020 at 06:28:59AM CEST, vasundhara-v.volam@...adcom.com wrote:
>> >On Mon, May 25, 2020 at 10:56 PM Jiri Pirko <jiri@...nulli.us> wrote:
>> >>
>> >> Sun, May 24, 2020 at 08:29:56AM CEST, vasundhara-v.volam@...adcom.com wrote:
>> >> >On Sun, May 24, 2020 at 10:23 AM Jiri Pirko <jiri@...nulli.us> wrote:
>> >> >>
>> >> >> Sat, May 23, 2020 at 08:08:22AM CEST, vasundhara-v.volam@...adcom.com wrote:
>> >> >> >Add a new "allow_fw_live_reset" generic device bool parameter. When
>> >> >> >parameter is set, user is allowed to reset the firmware in real time.
>> >> >> >
>> >> >> >This parameter is employed to communicate user consent or dissent for
>> >> >> >the live reset to happen. A separate command triggers the actual live
>> >> >> >reset.
>> >> >> >
>> >> >> >Cc: Jiri Pirko <jiri@...lanox.com>
>> >> >> >Signed-off-by: Vasundhara Volam <vasundhara-v.volam@...adcom.com>
>> >> >> >Signed-off-by: Michael Chan <michael.chan@...adcom.com>
>> >> >> >---
>> >> >> >v2: Rename param name to "allow_fw_live_reset" from
>> >> >> >"enable_hot_fw_reset".
>> >> >> >Update documentation for the param in devlink-params.rst file.
>> >> >> >---
>> >> >> > Documentation/networking/devlink/devlink-params.rst | 6 ++++++
>> >> >> > include/net/devlink.h                               | 4 ++++
>> >> >> > net/core/devlink.c                                  | 5 +++++
>> >> >> > 3 files changed, 15 insertions(+)
>> >> >> >
>> >> >> >diff --git a/Documentation/networking/devlink/devlink-params.rst b/Documentation/networking/devlink/devlink-params.rst
>> >> >> >index d075fd0..ad54dfb 100644
>> >> >> >--- a/Documentation/networking/devlink/devlink-params.rst
>> >> >> >+++ b/Documentation/networking/devlink/devlink-params.rst
>> >> >> >@@ -108,3 +108,9 @@ own name.
>> >> >> >    * - ``region_snapshot_enable``
>> >> >> >      - Boolean
>> >> >> >      - Enable capture of ``devlink-region`` snapshots.
>> >> >> >+   * - ``allow_fw_live_reset``
>> >> >> >+     - Boolean
>> >> >> >+     - Firmware live reset allows users to reset the firmware in real time.
>> >> >> >+       For example, after firmware upgrade, this feature can immediately reset
>> >> >> >+       to run the new firmware without reloading the driver or rebooting the
>> >> >>
>> >> >> This does not tell me anything about the reset being done on another
>> >> >> host. You need to emhasize that, in the name of the param too.
>> >> >I am not sure if I completely understand your query.
>> >> >
>> >> >Reset is actually initiated by one of the PF/host of the device, which
>> >> >resets the entire same device.
>> >> >
>> >> >Reset is not initiated by any other remote device/host.
>> >>
>> >> Well, in case of multihost system, it might be, right?
>> >>
>> >In case of multi-host system also, it is one of the host that triggers
>> >the reset, which resets the entire same device. I don't think this is
>> >remote.
>> >
>> >As the parameter is a device parameter, it is applicable to the entire
>> >device. When a user initiates the reset from any of the host in case
>> >of multi-host and any of the PF in case of stand-alone or smartNIC
>> >device, the entire device goes for a reset.
>> >
>> >I will be expanding the description to the following to make it more clear.
>> >
>> >------------------------
>> >- Firmware live reset allows users to reset the firmware in real time.
>> >For example, after firmware upgrade, this feature can immediately
>> >reset to run the new firmware without reloading the driver or
>> >rebooting the system.
>> >When a user initiates the reset from any of the host (in case of
>> >multi-host system) / PF (in case of stand-alone or smartNIC device),
>> >the entire device goes for a reset when the parameter is enabled.
>>
>> Sorry, this is still not clear. I think that you are mixing up two
>> different things:
>> 1) option of devlink reload to indicate that user is interested in "live
>>    reset" of firmware without reloading driver
>
>This is the option we are trying to add. If a user is interested in
>"live reset", he needs to enable the parameter to enable it in device
>capabilities, which is achieved by permanent configuration mode. When
>capability is enabled in the device, new firmware which is aware will
>allocate the resources and exposes the capability to host drivers.
>
>But firmware allows the "live reset" only when all the loaded drivers
>are aware of/supports the capability. For example, if any of the host
>is loaded with an old driver, "live reset" is not allowed until the
>driver is upgraded or unloaded. or if the host driver turns it off,
>then also "live reset" is not allowed.
>
>In case of runtime parameter cmode, if any of the host turns off the
>capability in the host driver, "live reset" is not allowed until the
>driver is unloaded or the user enables it again.
>
>To make it clear, I can add two parameters.
>
>1. enable_fw_live_reset - To indicate that the user is interested in
>"live reset". This will be a generic param.

As I wrote above, I believe this should be an option
to "devlink dev reload", not a param.


>
>2. allow_fw_live_reset - To indicate, if any of the host/PF turns it
>off, "live reset" is not allowed. This serves the purpose of what we
>are trying to add in runtime cmode.

Yeah.

>Do you want me to keep it as a driver-specific param?

There is nothing driver-specific about this.


>
>Please let me know if this is clear and makes less confusion.
>
>Thanks,
>Vasundhara
>
>> 2) devlink param that would indicate "I am okay if someone else (not by
>>    my devlink instance) resets my firmware".
>>
>> Could you please split?
>>
>>
>> >------------------------
>> >
>> >Thanks,
>> >Vasundhara
>> >>
>> >> >
>> >> >Thanks,
>> >> >Vasundhara
>> >> >>
>> >> >>
>> >> >>
>> >> >> >+       system.
>> >> >> >diff --git a/include/net/devlink.h b/include/net/devlink.h
>> >> >> >index 8ffc1b5c..488b61c 100644
>> >> >> >--- a/include/net/devlink.h
>> >> >> >+++ b/include/net/devlink.h
>> >> >> >@@ -406,6 +406,7 @@ enum devlink_param_generic_id {
>> >> >> >       DEVLINK_PARAM_GENERIC_ID_FW_LOAD_POLICY,
>> >> >> >       DEVLINK_PARAM_GENERIC_ID_RESET_DEV_ON_DRV_PROBE,
>> >> >> >       DEVLINK_PARAM_GENERIC_ID_ENABLE_ROCE,
>> >> >> >+      DEVLINK_PARAM_GENERIC_ID_ALLOW_FW_LIVE_RESET,
>> >> >> >
>> >> >> >       /* add new param generic ids above here*/
>> >> >> >       __DEVLINK_PARAM_GENERIC_ID_MAX,
>> >> >> >@@ -443,6 +444,9 @@ enum devlink_param_generic_id {
>> >> >> > #define DEVLINK_PARAM_GENERIC_ENABLE_ROCE_NAME "enable_roce"
>> >> >> > #define DEVLINK_PARAM_GENERIC_ENABLE_ROCE_TYPE DEVLINK_PARAM_TYPE_BOOL
>> >> >> >
>> >> >> >+#define DEVLINK_PARAM_GENERIC_ALLOW_FW_LIVE_RESET_NAME "allow_fw_live_reset"
>> >> >> >+#define DEVLINK_PARAM_GENERIC_ALLOW_FW_LIVE_RESET_TYPE DEVLINK_PARAM_TYPE_BOOL
>> >> >> >+
>> >> >> > #define DEVLINK_PARAM_GENERIC(_id, _cmodes, _get, _set, _validate)    \
>> >> >> > {                                                                     \
>> >> >> >       .id = DEVLINK_PARAM_GENERIC_ID_##_id,                           \
>> >> >> >diff --git a/net/core/devlink.c b/net/core/devlink.c
>> >> >> >index 7b76e5f..8544f23 100644
>> >> >> >--- a/net/core/devlink.c
>> >> >> >+++ b/net/core/devlink.c
>> >> >> >@@ -3011,6 +3011,11 @@ static int devlink_nl_cmd_flash_update(struct sk_buff *skb,
>> >> >> >               .name = DEVLINK_PARAM_GENERIC_ENABLE_ROCE_NAME,
>> >> >> >               .type = DEVLINK_PARAM_GENERIC_ENABLE_ROCE_TYPE,
>> >> >> >       },
>> >> >> >+      {
>> >> >> >+              .id = DEVLINK_PARAM_GENERIC_ID_ALLOW_FW_LIVE_RESET,
>> >> >> >+              .name = DEVLINK_PARAM_GENERIC_ALLOW_FW_LIVE_RESET_NAME,
>> >> >> >+              .type = DEVLINK_PARAM_GENERIC_ALLOW_FW_LIVE_RESET_TYPE,
>> >> >> >+      },
>> >> >> > };
>> >> >> >
>> >> >> > static int devlink_param_generic_verify(const struct devlink_param *param)
>> >> >> >--
>> >> >> >1.8.3.1
>> >> >> >

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