Re: [PATCH 2/3] hw/cxl/cxl-mailbox-utils.c: Added support for Clear Log (Opcode 0403h)

[Jonathan Cameron via <qemu-devel@nongnu.org>]

On Mon,  3 Feb 2025 11:29:49 +0530
Arpit Kumar <arpit1.kumar@samsung.com> wrote:

Add some description of what is being added here.

Key issue in here is that clearing the CEL doesn't make
sense. It is a description of what the device supports, there
is no state to clear in it.  To add this command you need
to pick a different log.

Jonathan


> Signed-off-by: Arpit Kumar <arpit1.kumar@samsung.com>
> Reviewed-by: Alok Rathore <alok.rathore@samsung.com>
> Reviewed-by: Krishna Kanth Reddy <krish.reddy@samsung.com>
> ---
>  hw/cxl/cxl-mailbox-utils.c | 36 ++++++++++++++++++++++++++++++++++++
>  1 file changed, 36 insertions(+)
> 
> diff --git a/hw/cxl/cxl-mailbox-utils.c b/hw/cxl/cxl-mailbox-utils.c
> index 3d66a425a9..5fd7f850c4 100644
> --- a/hw/cxl/cxl-mailbox-utils.c
> +++ b/hw/cxl/cxl-mailbox-utils.c
> @@ -77,6 +77,7 @@ enum {
>          #define GET_SUPPORTED 0x0
>          #define GET_LOG       0x1
>          #define GET_LOG_CAPABILITIES   0x2
> +        #define CLEAR_LOG     0x3
>      FEATURES    = 0x05,
>          #define GET_SUPPORTED 0x0
>          #define GET_FEATURE   0x1
> @@ -1115,6 +1116,39 @@ static CXLRetCode cmd_logs_get_log_capabilities(const struct cxl_cmd *cmd,
>      return CXL_MBOX_SUCCESS;
>  }
>  
> +/* CXL r3.1 Section 8.2.9.5.4: Clear Log (Opcode 0403h) */
> +static CXLRetCode cmd_logs_clear_log(const struct cxl_cmd *cmd,
> +                                     uint8_t *payload_in,
> +                                     size_t len_in,
> +                                     uint8_t *payload_out,
> +                                     size_t *len_out,
> +                                     CXLCCI *cci)
> +{
> +    int32_t cap_id;
> +    struct {
> +        QemuUUID uuid;
> +    } QEMU_PACKED QEMU_ALIGNED(8) * clear_log = (void *)payload_in;
> +
> +    cap_id = valid_log_check(&clear_log->uuid, cci);
> +    if (cap_id == -1) {
> +        return CXL_MBOX_INVALID_LOG;
> +    }

Follow on from previous patch, if this returns the cap pointer,
the following code wont have to index the array and should end up simpler.

> +
> +    if (cci->supported_log_cap[cap_id].param_flags.clear_log_supported) {
I would flip this.
    if (!(cap->param_flags & PARAM_FLAG_CLEAR_LOG_SUPPORTED)) {
        return CXL_MBOX_UNSUPPORTED;
    }

    
> +        switch (cap_id) {
> +        case CEL:

So if we return the cap as suggested, it will have to reference what it is
or provide a callback (which might be cleaner as this grows).

However, what does clearly the command effects log mean?
This makes no sense.  So if you want to implement clear_log you
need to implement a different log to clear.

> +            memset(cci->cel_log, 0, (1 << 16) * sizeof(struct cel_log));
> +            cci->cel_size = 0;
> +            break;
> +        default:
> +            return CXL_MBOX_UNSUPPORTED;
> +        }
> +    } else {
> +        return CXL_MBOX_UNSUPPORTED;
> +    }
> +    return CXL_MBOX_SUCCESS;
> +}
> +
>  /* CXL r3.1 section 8.2.9.6: Features */
>  /*
>   * Get Supported Features output payload
> @@ -2882,6 +2916,8 @@ static const struct cxl_cmd cxl_cmd_set[256][256] = {
>      [LOGS][GET_LOG] = { "LOGS_GET_LOG", cmd_logs_get_log, 0x18, 0 },
>      [LOGS][GET_LOG_CAPABILITIES] = { "LOGS_GET_LOG_CAPABILITIES",
>                                       cmd_logs_get_log_capabilities, 0x10, 0 },
> +    [LOGS][CLEAR_LOG] = { "LOGS_CLEAR_LOG", cmd_logs_clear_log, 0x10,
> +                          CXL_MBOX_IMMEDIATE_LOG_CHANGE},
>      [FEATURES][GET_SUPPORTED] = { "FEATURES_GET_SUPPORTED",
>                                    cmd_features_get_supported, 0x8, 0 },
>      [FEATURES][GET_FEATURE] = { "FEATURES_GET_FEATURE",