linux-kernel - Re: [PATCH V2] arm64/cpufeature: Drop open encodings while extracting parange

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Date:   Mon, 18 May 2020 19:46:58 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Will Deacon <will@...nel.org>
Cc:     Anshuman Khandual <anshuman.khandual@....com>,
        mark.rutland@....com, Catalin Marinas <catalin.marinas@....com>,
        linux-kernel@...r.kernel.org, James Morse <james.morse@....com>,
        kvmarm@...ts.cs.columbia.edu, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH V2] arm64/cpufeature: Drop open encodings while extracting parange

On Mon, 18 May 2020 18:09:34 +0100,
Will Deacon <will@...nel.org> wrote:
> 
> On Mon, May 18, 2020 at 05:59:59PM +0100, Will Deacon wrote:
> > On Wed, May 13, 2020 at 02:33:34PM +0530, Anshuman Khandual wrote:
> > > Currently there are multiple instances of parange feature width mask open
> > > encodings while fetching it's value. Even the width mask value (0x7) itself
> > > is not accurate. It should be (0xf) per ID_AA64MMFR0_EL1.PARange[3:0] as in
> > > ARM ARM (0487F.a). Replace them with cpuid_feature_extract_unsigned_field()
> > > which can extract given standard feature (4 bits width i.e 0xf mask) field.
> > > 
> > > Cc: Catalin Marinas <catalin.marinas@....com>
> > > Cc: Will Deacon <will@...nel.org>
> > > Cc: Marc Zyngier <maz@...nel.org>
> > > Cc: James Morse <james.morse@....com>
> > > Cc: kvmarm@...ts.cs.columbia.edu
> > > Cc: linux-arm-kernel@...ts.infradead.org
> > > Cc: linux-kernel@...r.kernel.org
> > > 
> > > Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> > > ---
> > > Changes in V2:
> > > 
> > > - Used cpuid_feature_extract_unsigned_field() per Mark
> > > 
> > > Changes in V1: (https://patchwork.kernel.org/patch/11541913/)
> > > 
> > >  arch/arm64/kernel/cpufeature.c |  3 ++-
> > >  arch/arm64/kvm/reset.c         | 11 ++++++++---
> > >  2 files changed, 10 insertions(+), 4 deletions(-)
> > 
> > Acked-by: Will Deacon <will@...nel.org>
> > 
> > I'm assuming Marc will take this, but let me know if it should go via arm64
> > instead (where we have a bunch of other cpufeature stuff queued).
> 
> Hmm, but having just spotted [1], it looks like we might need a bit of
> co-ordination here. Marc?

Yeah, there is a clear dependency between the two. I'm happy to take
both patches via the KVM tree, or to have a shared branch with the
arm64 tree (we already have one for Andrew's generic AT patch).

Just let me know,

	M.

-- 
Without deviation from the norm, progress is not possible.