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

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Message-ID: <87h7ag31hv.fsf@mpe.ellerman.id.au>
Date:   Fri, 07 Jan 2022 10:09:32 +1100
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Laurent Dufour <ldufour@...ux.ibm.com>
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

Laurent Dufour <ldufour@...ux.ibm.com> writes:
> Happy New Year, Michael!
>
> Do you consider taking that patch soon?

I did but I was hoping you and Nathan could come to an agreement.

Looks like you did while I was sleeping, perfect :)

I'll pick up v5.

cheers


> 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);