linux-kernel - Re: [PATCH v4] powerpc/pseries: read the lpar name from the firmware

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Message-ID: <25527544-b0ac-596c-3876-560493b99f6b@linux.ibm.com>
Date:   Wed, 5 Jan 2022 17:13:59 +0100
From:   Laurent Dufour <ldufour@...ux.ibm.com>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     Nathan Lynch <nathanl@...ux.ibm.com>, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH v4] powerpc/pseries: read the lpar name from the firmware

Happy New Year, Michael!

Do you consider taking that patch soon?

Thanks,
Laurent.

On 07/12/2021, 18:11:09, Laurent Dufour wrote:
> The LPAR name may be changed after the LPAR has been started in the HMC.
> In that case lparstat command is not reporting the updated value because it
> reads it from the device tree which is read at boot time.
> 
> However this value could be read from RTAS.
> 
> Adding this value in the /proc/powerpc/lparcfg output allows to read the
> updated value.
> 
> Cc: Nathan Lynch <nathanl@...ux.ibm.com>
> Signed-off-by: Laurent Dufour <ldufour@...ux.ibm.com>
> ---
> v4:
>  address Nathan's new comments limiting size of the buffer.
> v3:
>  address Michael's comments.
> v2:
>  address Nathan's comments.
>  change title to partition_name aligning with existing partition_id
> ---
>  arch/powerpc/platforms/pseries/lparcfg.c | 54 ++++++++++++++++++++++++
>  1 file changed, 54 insertions(+)
> 
> diff --git a/arch/powerpc/platforms/pseries/lparcfg.c b/arch/powerpc/platforms/pseries/lparcfg.c
> index f71eac74ea92..058d9a5fe545 100644
> --- a/arch/powerpc/platforms/pseries/lparcfg.c
> +++ b/arch/powerpc/platforms/pseries/lparcfg.c
> @@ -311,6 +311,59 @@ static void parse_mpp_x_data(struct seq_file *m)
>  		seq_printf(m, "coalesce_pool_spurr=%ld\n", mpp_x_data.pool_spurr_cycles);
>  }
>  
> +/*
> + * PAPR defines, in section "7.3.16 System Parameters Option", the token 55 to
> + * read the LPAR name, and the largest output data to 4000 + 2 bytes length.
> + */
> +#define SPLPAR_LPAR_NAME_TOKEN	55
> +#define GET_SYS_PARM_BUF_SIZE	4002
> +#if GET_SYS_PARM_BUF_SIZE > RTAS_DATA_BUF_SIZE
> +#error "GET_SYS_PARM_BUF_SIZE is larger than RTAS_DATA_BUF_SIZE"
> +#endif
> +static void read_lpar_name(struct seq_file *m)
> +{
> +	int rc, len, token;
> +	union {
> +		char raw_buffer[GET_SYS_PARM_BUF_SIZE];
> +		struct {
> +			__be16 len;
> +			char name[GET_SYS_PARM_BUF_SIZE-2];
> +		};
> +	} *local_buffer;
> +
> +	token = rtas_token("ibm,get-system-parameter");
> +	if (token == RTAS_UNKNOWN_SERVICE)
> +		return;
> +
> +	local_buffer = kmalloc(sizeof(*local_buffer), GFP_KERNEL);
> +	if (!local_buffer)
> +		return;
> +
> +	do {
> +		spin_lock(&rtas_data_buf_lock);
> +		memset(rtas_data_buf, 0, sizeof(*local_buffer));
> +		rc = rtas_call(token, 3, 1, NULL, SPLPAR_LPAR_NAME_TOKEN,
> +			       __pa(rtas_data_buf), sizeof(*local_buffer));
> +		if (!rc)
> +			memcpy(local_buffer->raw_buffer, rtas_data_buf,
> +			       sizeof(local_buffer->raw_buffer));
> +		spin_unlock(&rtas_data_buf_lock);
> +	} while (rtas_busy_delay(rc));
> +
> +	if (!rc) {
> +		/* Force end of string */
> +		len = min((int) be16_to_cpu(local_buffer->len),
> +			  (int) sizeof(local_buffer->name)-1);
> +		local_buffer->name[len] = '\0';
> +
> +		seq_printf(m, "partition_name=%s\n", local_buffer->name);
> +	} else
> +		pr_err_once("Error calling get-system-parameter (0x%x)\n", rc);
> +
> +	kfree(local_buffer);
> +}
> +
> +
>  #define SPLPAR_CHARACTERISTICS_TOKEN 20
>  #define SPLPAR_MAXLENGTH 1026*(sizeof(char))
>  
> @@ -496,6 +549,7 @@ static int pseries_lparcfg_data(struct seq_file *m, void *v)
>  
>  	if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
>  		/* this call handles the ibm,get-system-parameter contents */
> +		read_lpar_name(m);
>  		parse_system_parameter_string(m);
>  		parse_ppp_data(m);
>  		parse_mpp_data(m);