linux-kernel - Re: [PATCH v3 03/17] riscv: sbi: add SBI FWFT extension calls

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Message-ID: <c411446b-e161-48fa-a94b-e04c00f62b01@rivosinc.com>
Date: Fri, 14 Mar 2025 12:21:24 +0100
From: Clément Léger <cleger@...osinc.com>
To: Andrew Jones <ajones@...tanamicro.com>
Cc: Paul Walmsley <paul.walmsley@...ive.com>,
 Palmer Dabbelt <palmer@...belt.com>, Anup Patel <anup@...infault.org>,
 Atish Patra <atishp@...shpatra.org>, Shuah Khan <shuah@...nel.org>,
 Jonathan Corbet <corbet@....net>, linux-riscv@...ts.infradead.org,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 kvm@...r.kernel.org, kvm-riscv@...ts.infradead.org,
 linux-kselftest@...r.kernel.org, Samuel Holland <samuel.holland@...ive.com>
Subject: Re: [PATCH v3 03/17] riscv: sbi: add SBI FWFT extension calls



On 13/03/2025 13:44, Andrew Jones wrote:
> On Mon, Mar 10, 2025 at 04:12:10PM +0100, Clément Léger wrote:
>> Add FWFT extension calls. This will be ratified in SBI V3.0 hence, it is
>> provided as a separate commit that can be left out if needed.
>>
>> Signed-off-by: Clément Léger <cleger@...osinc.com>
>> ---
>>  arch/riscv/kernel/sbi.c | 30 ++++++++++++++++++++++++++++--
>>  1 file changed, 28 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c
>> index 256910db1307..af8e2199e32d 100644
>> --- a/arch/riscv/kernel/sbi.c
>> +++ b/arch/riscv/kernel/sbi.c
>> @@ -299,9 +299,19 @@ static int __sbi_rfence_v02(int fid, const struct cpumask *cpu_mask,
>>  	return 0;
>>  }
>>  
>> +static bool sbi_fwft_supported;
>> +
>>  int sbi_fwft_get(u32 feature, unsigned long *value)
>>  {
>> -	return -EOPNOTSUPP;
>> +	struct sbiret ret;
>> +
>> +	if (!sbi_fwft_supported)
>> +		return -EOPNOTSUPP;
>> +
>> +	ret = sbi_ecall(SBI_EXT_FWFT, SBI_EXT_FWFT_GET,
>> +			feature, 0, 0, 0, 0, 0);
>> +
>> +	return sbi_err_map_linux_errno(ret.error);
>>  }
>>  
>>  /**
>> @@ -314,7 +324,15 @@ int sbi_fwft_get(u32 feature, unsigned long *value)
>>   */
>>  int sbi_fwft_set(u32 feature, unsigned long value, unsigned long flags)
>>  {
>> -	return -EOPNOTSUPP;
>> +	struct sbiret ret;
>> +
>> +	if (!sbi_fwft_supported)
>> +		return -EOPNOTSUPP;
>> +
>> +	ret = sbi_ecall(SBI_EXT_FWFT, SBI_EXT_FWFT_SET,
>> +			feature, value, flags, 0, 0, 0);
>> +
>> +	return sbi_err_map_linux_errno(ret.error);
> 
> sbi_err_map_linux_errno() doesn't know about SBI_ERR_DENIED_LOCKED.

Not only it doesn't knows about DENIED_LOCKED but also another bunch of
errors. I'll add them in a separate commit.

> 
>>  }
>>  
>>  struct fwft_set_req {
>> @@ -389,6 +407,9 @@ static int sbi_fwft_feature_local_set(u32 feature, unsigned long value,
>>  int sbi_fwft_all_cpus_set(u32 feature, unsigned long value, unsigned long flags,
>>  			  bool revert_on_fail)
>>  {
>> +	if (!sbi_fwft_supported)
>> +		return -EOPNOTSUPP;
>> +
>>  	if (feature & SBI_FWFT_GLOBAL_FEATURE_BIT)
>>  		return sbi_fwft_set(feature, value, flags);
>>  
>> @@ -719,6 +740,11 @@ void __init sbi_init(void)
>>  			pr_info("SBI DBCN extension detected\n");
>>  			sbi_debug_console_available = true;
>>  		}
>> +		if ((sbi_spec_version >= sbi_mk_version(2, 0)) &&
> 
> Should check sbi_mk_version(3, 0)

Oh yes that was for testing purpose and I incorrectly squashed it.

> 
>> +		    (sbi_probe_extension(SBI_EXT_FWFT) > 0)) {
>> +			pr_info("SBI FWFT extension detected\n");
>> +			sbi_fwft_supported = true;
>> +		}
>>  	} else {
>>  		__sbi_set_timer = __sbi_set_timer_v01;
>>  		__sbi_send_ipi	= __sbi_send_ipi_v01;
>> -- 
>> 2.47.2
>>
> 

Thanks,

Clément

> Thanks,
> drew