[PATCH] sbi: fwft: clear the config lock when warm boot

[Samuel Holland]

Hi Xiang,

On 2024-11-21 8:45 PM, Xiang W wrote:
> 在 2024-11-15五的 15:33 +0800，Nick Hu写道：
>> The hotplug cpu should clear the fwft config's SBI_FWFT_SET_FLAG_LOCK
>> in the warm boot flow otherwise the cpu can't set the menvcfg.sse by
>> SBI_EXT_FWFT_SET sbi call and cause the illegal instruction when
>> accessing the CSR_SSP in kernel.
>>
>> Signed-off-by: Nick Hu <nick.hu at sifive.com>
> 
> In sbi_fwft_init, the memory for fwft_hart_state is allocated by 
> sbi_zalloc, which ensures that flags is 0. So no additional code
> is needed to clear the SBI_FWFT_SET_FLAG_LOCK bit.

That allocation only occurs the first time a hart is started. After a
sbi_hsm_hart_stop() and sbi_hsm_hart_start(), the FWFT features will be reset to
their default values per the SBI spec, and the flags need to be reset as well.

Regards,
Samuel

>> ---
>>  lib/sbi/sbi_fwft.c | 15 +++++++++++++++
>>  1 file changed, 15 insertions(+)
>>
>> diff --git a/lib/sbi/sbi_fwft.c b/lib/sbi/sbi_fwft.c
>> index 9cf14c16..0cb165b4 100644
>> --- a/lib/sbi/sbi_fwft.c
>> +++ b/lib/sbi/sbi_fwft.c
>> @@ -311,6 +311,18 @@ static int fwft_get_feature(enum sbi_fwft_feature_t feature,
>>  	return SBI_SUCCESS;
>>  }
>>  
>> +static void fwft_clear_config_lock(enum sbi_fwft_feature_t feature)
>> +{
>> +	int ret;
>> +	struct fwft_config *conf;
>> +
>> +	ret = fwft_get_feature(feature, &conf);
>> +	if (ret)
>> +		return;
>> +
>> +	conf->flags &= ~SBI_FWFT_SET_FLAG_LOCK;
>> +}
>> +
>>  int sbi_fwft_set(enum sbi_fwft_feature_t feature, unsigned long value,
>>  		 unsigned long flags)
>>  {
>> @@ -414,5 +426,8 @@ int sbi_fwft_init(struct sbi_scratch *scratch, bool cold_boot)
>>  		fwft_set_hart_state_ptr(scratch, fhs);
>>  	}
>>  
>> +	for (i = 0; i < array_size(features); i++)
>> +		fwft_clear_config_lock(features[i].id);
>> +
>>  	return 0;
>>  }
>> -- 
>> 2.34.1
>>
>>
> 
>