Re: [PATCH v2 3/6] arm64: cpufeature: Extend bbml2_noabort support list

[Linu Cherian <linu.cherian@arm.com>]

On Wed, Jul 08, 2026 at 03:53:59PM +0100, Suzuki K Poulose wrote:
> On 08/07/2026 15:43, Linu Cherian wrote:
> > Add below cpus to the midr list, which supports
> > BBML2_NOABORT.
> > 
> > Cortex A520(AE)
> > Cortex A715
> > Cortex A720(AE)
> > Cortex A725
> > Neoverse N3
> > C1-Nano
> > C1-Pro
> > C1-Ultra
> > C1-Premium
> > 
> > C1-Ultra and C1-Premium both suffer from erratum 3683289,
> > where Break-Before-Make must be followed to avoid a livelock.
> > For both CPUs, the erratum is fixed from r1p1.
> > Hence we do not enable BBML2_NOABORT for CPU revisions <= r1p0.
> 
> Please could you also update the list of errata here :
> 
> Documentation/arch/arm64/silicon-errata.rst

Ack.

> 
> > 
> > The relevant SDENs are:
> > * C1-Ultra: https://developer.arm.com/documentation/111077/9-00/
> > * C1-Premium: https://developer.arm.com/documentation/111078/9-00/
> > 
> > Signed-off-by: Linu Cherian <linu.cherian@arm.com>
> > ---
> >   arch/arm64/kernel/cpufeature.c | 9 +++++++++
> >   1 file changed, 9 insertions(+)
> > 
> > diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
> > index 9a22df0c5120..adcabea80fcb 100644
> > --- a/arch/arm64/kernel/cpufeature.c
> > +++ b/arch/arm64/kernel/cpufeature.c
> > @@ -2152,6 +2152,15 @@ bool cpu_supports_bbml2_noabort(void)
> >   		MIDR_ALL_VERSIONS(MIDR_NVIDIA_OLYMPUS),
> >   		MIDR_ALL_VERSIONS(MIDR_AMPERE1),
> >   		MIDR_ALL_VERSIONS(MIDR_AMPERE1A),
> > +		MIDR_ALL_VERSIONS(MIDR_CORTEX_A520AE),
> > +		MIDR_ALL_VERSIONS(MIDR_CORTEX_A715),
> > +		MIDR_ALL_VERSIONS(MIDR_CORTEX_A720AE),
> > +		MIDR_ALL_VERSIONS(MIDR_CORTEX_A725),
> > +		MIDR_ALL_VERSIONS(MIDR_NEOVERSE_N3),
> > +		MIDR_ALL_VERSIONS(MIDR_C1_NANO),
> > +		MIDR_ALL_VERSIONS(MIDR_C1_PRO),
> 
> And mention it here, so that it is evident from the code alone ?
> 
Ack.

> > +		MIDR_REV_RANGE(MIDR_C1_ULTRA, 1, 1, 0xf),
> > +		MIDR_REV_RANGE(MIDR_C1_PREMIUM, 1, 1, 0xf),
> 
> 
> Suzuki
> 
> 
> >   		{}
> >   	};
>