[v6] RISC-V SBI v2.0 PMU improvements and Perf sampling in KVM guest

[PATCH v6 07/24] RISC-V: Use the minor version mask while computing sbi version

Posted by Atish Patra 1 year, 10 months ago

As per the SBI specification, minor version is encoded in the
lower 24 bits only. Make sure that the SBI version is computed
with the appropriate mask.

Currently, there is no minor version in use. Thus, it doesn't
change anything functionality but it is good to be compliant with
the specification.

Signed-off-by: Atish Patra <atishp@rivosinc.com>
---
 arch/riscv/include/asm/sbi.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
index f31650b10899..935b082d6a6c 100644
--- a/arch/riscv/include/asm/sbi.h
+++ b/arch/riscv/include/asm/sbi.h
@@ -367,8 +367,8 @@ static inline unsigned long sbi_minor_version(void)
 static inline unsigned long sbi_mk_version(unsigned long major,
 					    unsigned long minor)
 {
-	return ((major & SBI_SPEC_VERSION_MAJOR_MASK) <<
-		SBI_SPEC_VERSION_MAJOR_SHIFT) | minor;
+	return ((major & SBI_SPEC_VERSION_MAJOR_MASK) << SBI_SPEC_VERSION_MAJOR_SHIFT
+		| (minor & SBI_SPEC_VERSION_MINOR_MASK));
 }
 
 int sbi_err_map_linux_errno(int err);
-- 
2.34.1

Re: [PATCH v6 07/24] RISC-V: Use the minor version mask while computing sbi version

Posted by Andrew Jones 1 year, 10 months ago

On Wed, Apr 10, 2024 at 05:07:35PM -0700, Atish Patra wrote:
> As per the SBI specification, minor version is encoded in the
> lower 24 bits only. Make sure that the SBI version is computed
> with the appropriate mask.
> 
> Currently, there is no minor version in use. Thus, it doesn't
> change anything functionality but it is good to be compliant with
> the specification.
> 
> Signed-off-by: Atish Patra <atishp@rivosinc.com>
> ---
>  arch/riscv/include/asm/sbi.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> index f31650b10899..935b082d6a6c 100644
> --- a/arch/riscv/include/asm/sbi.h
> +++ b/arch/riscv/include/asm/sbi.h
> @@ -367,8 +367,8 @@ static inline unsigned long sbi_minor_version(void)
>  static inline unsigned long sbi_mk_version(unsigned long major,
>  					    unsigned long minor)
>  {
> -	return ((major & SBI_SPEC_VERSION_MAJOR_MASK) <<
> -		SBI_SPEC_VERSION_MAJOR_SHIFT) | minor;
> +	return ((major & SBI_SPEC_VERSION_MAJOR_MASK) << SBI_SPEC_VERSION_MAJOR_SHIFT
> +		| (minor & SBI_SPEC_VERSION_MINOR_MASK));

The previous version had ((major & major_mask) << major_shift) | minor
(parentheses around all the major bits before the OR). Now we have
parentheses around everything, which aren't necessary, and no longer
have them around all the major bits before the OR. We don't need the
parentheses around the major bits, since shift has higher precedence
than OR, but I'd probably keep them.

Otherwise,

Reviewed-by: Andrew Jones <ajones@ventanamicro.com>

>  }
>  
>  int sbi_err_map_linux_errno(int err);
> -- 
> 2.34.1
>

Re: [PATCH v6 07/24] RISC-V: Use the minor version mask while computing sbi version

Posted by Atish Patra 1 year, 9 months ago

On 4/15/24 06:06, Andrew Jones wrote:
> On Wed, Apr 10, 2024 at 05:07:35PM -0700, Atish Patra wrote:
>> As per the SBI specification, minor version is encoded in the
>> lower 24 bits only. Make sure that the SBI version is computed
>> with the appropriate mask.
>>
>> Currently, there is no minor version in use. Thus, it doesn't
>> change anything functionality but it is good to be compliant with
>> the specification.
>>
>> Signed-off-by: Atish Patra <atishp@rivosinc.com>
>> ---
>>   arch/riscv/include/asm/sbi.h | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
>> index f31650b10899..935b082d6a6c 100644
>> --- a/arch/riscv/include/asm/sbi.h
>> +++ b/arch/riscv/include/asm/sbi.h
>> @@ -367,8 +367,8 @@ static inline unsigned long sbi_minor_version(void)
>>   static inline unsigned long sbi_mk_version(unsigned long major,
>>   					    unsigned long minor)
>>   {
>> -	return ((major & SBI_SPEC_VERSION_MAJOR_MASK) <<
>> -		SBI_SPEC_VERSION_MAJOR_SHIFT) | minor;
>> +	return ((major & SBI_SPEC_VERSION_MAJOR_MASK) << SBI_SPEC_VERSION_MAJOR_SHIFT
>> +		| (minor & SBI_SPEC_VERSION_MINOR_MASK));
> 
> The previous version had ((major & major_mask) << major_shift) | minor
> (parentheses around all the major bits before the OR). Now we have
> parentheses around everything, which aren't necessary, and no longer

We have to use parentheses around | to avoid compiler warnings 
(-Wparentheses)

Are you only concerned about the outer parentheses ? I have removed it.

> have them around all the major bits before the OR. We don't need the
> parentheses around the major bits, since shift has higher precedence
> than OR, but I'd probably keep them.
> 

Is this what you prefer?

return ((major & SBI_SPEC_VERSION_MAJOR_MASK) << 
SBI_SPEC_VERSION_MAJOR_SHIFT) | (minor & SBI_SPEC_VERSION_MINOR_MASK); 
 



> Otherwise,
> 
> Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> 
>>   }
>>   
>>   int sbi_err_map_linux_errno(int err);
>> -- 
>> 2.34.1
>>
> 
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

Re: [PATCH v6 07/24] RISC-V: Use the minor version mask while computing sbi version

Posted by Andrew Jones 1 year, 9 months ago

On Tue, Apr 16, 2024 at 01:31:27AM -0700, Atish Patra wrote:
> On 4/15/24 06:06, Andrew Jones wrote:
> > On Wed, Apr 10, 2024 at 05:07:35PM -0700, Atish Patra wrote:
> > > As per the SBI specification, minor version is encoded in the
> > > lower 24 bits only. Make sure that the SBI version is computed
> > > with the appropriate mask.
> > > 
> > > Currently, there is no minor version in use. Thus, it doesn't
> > > change anything functionality but it is good to be compliant with
> > > the specification.
> > > 
> > > Signed-off-by: Atish Patra <atishp@rivosinc.com>
> > > ---
> > >   arch/riscv/include/asm/sbi.h | 4 ++--
> > >   1 file changed, 2 insertions(+), 2 deletions(-)
> > > 
> > > diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h
> > > index f31650b10899..935b082d6a6c 100644
> > > --- a/arch/riscv/include/asm/sbi.h
> > > +++ b/arch/riscv/include/asm/sbi.h
> > > @@ -367,8 +367,8 @@ static inline unsigned long sbi_minor_version(void)
> > >   static inline unsigned long sbi_mk_version(unsigned long major,
> > >   					    unsigned long minor)
> > >   {
> > > -	return ((major & SBI_SPEC_VERSION_MAJOR_MASK) <<
> > > -		SBI_SPEC_VERSION_MAJOR_SHIFT) | minor;
> > > +	return ((major & SBI_SPEC_VERSION_MAJOR_MASK) << SBI_SPEC_VERSION_MAJOR_SHIFT
> > > +		| (minor & SBI_SPEC_VERSION_MINOR_MASK));
> > 
> > The previous version had ((major & major_mask) << major_shift) | minor
> > (parentheses around all the major bits before the OR). Now we have
> > parentheses around everything, which aren't necessary, and no longer
> 
> We have to use parentheses around | to avoid compiler warnings
> (-Wparentheses)
> 
> Are you only concerned about the outer parentheses ? I have removed it.
> 
> > have them around all the major bits before the OR. We don't need the
> > parentheses around the major bits, since shift has higher precedence
> > than OR, but I'd probably keep them.
> > 
> 
> Is this what you prefer?
> 
> return ((major & SBI_SPEC_VERSION_MAJOR_MASK) <<
> SBI_SPEC_VERSION_MAJOR_SHIFT) | (minor & SBI_SPEC_VERSION_MINOR_MASK);

Yup

Thanks,
drew

> 
> 
> 
> 
> > Otherwise,
> > 
> > Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
> > 
> > >   }
> > >   int sbi_err_map_linux_errno(int err);
> > > -- 
> > > 2.34.1
> > > 
> > 
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
>