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

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Date: Tue, 16 Apr 2024 10:49:20 +0200
From: Andrew Jones <ajones@...tanamicro.com>
To: Atish Patra <atishp@...osinc.com>
Cc: linux-kernel@...r.kernel.org, Ajay Kaher <ajay.kaher@...adcom.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alexghiti@...osinc.com>, 
	Alexey Makhalov <alexey.amakhalov@...adcom.com>, Anup Patel <anup@...infault.org>, 
	Atish Patra <atishp@...shpatra.org>, 
	Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>, Conor Dooley <conor.dooley@...rochip.com>, 
	Juergen Gross <jgross@...e.com>, kvm-riscv@...ts.infradead.org, kvm@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, linux-riscv@...ts.infradead.org, 
	Mark Rutland <mark.rutland@....com>, Palmer Dabbelt <palmer@...belt.com>, 
	Paolo Bonzini <pbonzini@...hat.com>, Paul Walmsley <paul.walmsley@...ive.com>, 
	Shuah Khan <shuah@...nel.org>, virtualization@...ts.linux.dev, Will Deacon <will@...nel.org>, 
	x86@...nel.org
Subject: Re: [PATCH v6 07/24] RISC-V: Use the minor version mask while
 computing sbi version

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@...osinc.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@...tanamicro.com>
> > 
> > >   }
> > >   int sbi_err_map_linux_errno(int err);
> > > -- 
> > > 2.34.1
> > > 
> > 
> > _______________________________________________
> > linux-riscv mailing list
> > linux-riscv@...ts.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-riscv
>

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