[PATCH v3 2/4] lib: sbi: fwft: add support for SBI_FWFT_MISALIGNED_EXC_DELEG

[Clément Léger]

On 21/06/2024 15:50, Andrew Jones wrote:
> On Wed, Jun 19, 2024 at 11:42:40AM GMT, Clément Léger wrote:
>> Add support for SBI_FWFT_MISALIGNED_EXC_DELEG withing FWFT support. This
>> support allows to delegate misaligned accesses traps.
>>
>> Signed-off-by: Clément Léger <cleger at rivosinc.com>
>> ---
>>  lib/sbi/sbi_fwft.c | 39 ++++++++++++++++++++++++++++++++++++++-
>>  lib/sbi/sbi_hsm.c  |  3 +++
>>  2 files changed, 41 insertions(+), 1 deletion(-)
>>
>> diff --git a/lib/sbi/sbi_fwft.c b/lib/sbi/sbi_fwft.c
>> index b302b5d..289a344 100644
>> --- a/lib/sbi/sbi_fwft.c
>> +++ b/lib/sbi/sbi_fwft.c
>> @@ -32,6 +32,8 @@ static unsigned long fwft_ptr_offset;
>>  #define fwft_set_hart_state_ptr(__scratch, __phs)			\
>>  	sbi_scratch_write_type((__scratch), void *, fwft_ptr_offset, (__phs))
>>  
>> +#define MIS_DELEG (1UL << CAUSE_MISALIGNED_LOAD | 1UL << CAUSE_MISALIGNED_STORE)
>> +
>>  struct fwft_config;
>>  
>>  struct fwft_feature {
>> @@ -71,6 +73,33 @@ static bool fwft_is_defined_feature(enum sbi_fwft_feature_t feature)
>>  	return false;
>>  }
>>  
>> +static int fwft_misaligned_delegation_supported(struct fwft_config *conf)
>> +{
>> +	if (!misa_extension('S'))
>> +		return SBI_ENOTSUPP;
>> +
>> +	return SBI_OK;
>> +}
>> +
>> +static int fwft_set_misaligned_delegation(struct fwft_config *conf,
>> +					 unsigned long value)
>> +{
>> +	if (value)
>> +		csr_set(CSR_MEDELEG, MIS_DELEG);
>> +	else
>> +		csr_clear(CSR_MEDELEG, MIS_DELEG);
> 
> Sorry for my late review. This should be
> 
>   if (value == 1)
>      csr_set(CSR_MEDELEG, MIS_DELEG);
>   else if (value == 0)
>      csr_clear(CSR_MEDELEG, MIS_DELEG);
>   else
>      return SBI_EINVAL;
> 
> It's unlikely we'll ever extend the inputs/behaviors, but if we don't
> check for the inputs explicitly now, then we never can.
> 
> And same comment for SBI_FWFT_PTE_AD_HW_UPDATING.

Arg, I thought I had this right but I might have dropped it at some
point. But agreed this needs to be checked thoroughly. I'll send a fix.

Thanks,

Clément

> 
> Thanks,
> drew
> 
>> +
>> +	return SBI_OK;
>> +}
>> +
>> +static int fwft_get_misaligned_delegation(struct fwft_config *conf,
>> +					 unsigned long *value)
>> +{
>> +	*value = (csr_read(CSR_MEDELEG) & MIS_DELEG) != 0;
>> +
>> +	return SBI_OK;
>> +}
>> +
>>  static struct fwft_config* get_feature_config(enum sbi_fwft_feature_t feature)
>>  {
>>  	int i;
>> @@ -148,7 +177,15 @@ int sbi_fwft_get(enum sbi_fwft_feature_t feature, unsigned long *out_val)
>>  	return conf->feature->get(conf, out_val);
>>  }
>>  
>> -static const struct fwft_feature features[] = {};
>> +static const struct fwft_feature features[] =
>> +{
>> +	{
>> +		.id = SBI_FWFT_MISALIGNED_EXC_DELEG,
>> +		.supported = fwft_misaligned_delegation_supported,
>> +		.set = fwft_set_misaligned_delegation,
>> +		.get = fwft_get_misaligned_delegation,
>> +	},
>> +};
>>  
>>  int sbi_fwft_init(struct sbi_scratch *scratch, bool cold_boot)
>>  {
>> diff --git a/lib/sbi/sbi_hsm.c b/lib/sbi/sbi_hsm.c
>> index be48d64..2b23e13 100644
>> --- a/lib/sbi/sbi_hsm.c
>> +++ b/lib/sbi/sbi_hsm.c
>> @@ -44,6 +44,7 @@ struct sbi_hsm_data {
>>  	unsigned long suspend_type;
>>  	unsigned long saved_mie;
>>  	unsigned long saved_mip;
>> +	unsigned long saved_medeleg;
>>  	atomic_t start_ticket;
>>  };
>>  
>> @@ -417,6 +418,7 @@ void __sbi_hsm_suspend_non_ret_save(struct sbi_scratch *scratch)
>>  
>>  	hdata->saved_mie = csr_read(CSR_MIE);
>>  	hdata->saved_mip = csr_read(CSR_MIP) & (MIP_SSIP | MIP_STIP);
>> +	hdata->saved_medeleg = csr_read(CSR_MEDELEG);
>>  }
>>  
>>  static void __sbi_hsm_suspend_non_ret_restore(struct sbi_scratch *scratch)
>> @@ -424,6 +426,7 @@ static void __sbi_hsm_suspend_non_ret_restore(struct sbi_scratch *scratch)
>>  	struct sbi_hsm_data *hdata = sbi_scratch_offset_ptr(scratch,
>>  							    hart_data_offset);
>>  
>> +	csr_write(CSR_MEDELEG, hdata->saved_medeleg);
>>  	csr_write(CSR_MIE, hdata->saved_mie);
>>  	csr_set(CSR_MIP, (hdata->saved_mip & (MIP_SSIP | MIP_STIP)));
>>  }
>> -- 
>> 2.45.2
>>
>>
>> -- 
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