Re: [PATCH v2 1/3] KVM: arm64: Print warning when cpu erratum can cause guests to deadlock

From: Rob Herring <robh@kernel.org>
To: Will Deacon <will@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
	"moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE"
	<linux-arm-kernel@lists.infradead.org>,
	Marc Zyngier <maz@kernel.org>,
	kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH v2 1/3] KVM: arm64: Print warning when cpu erratum can cause guests to deadlock
Date: Thu, 2 Jul 2020 08:04:43 -0600	[thread overview]
Message-ID: <CAL_JsqLnZHXjnYf3s6FJnVKf4kN1fhRgJov=Sb3H6J=Yro+cQg@mail.gmail.com> (raw)
In-Reply-To: <20200702114527.GB16499@willie-the-truck>

On Thu, Jul 2, 2020 at 5:45 AM Will Deacon <will@kernel.org> wrote:
>
> On Wed, Jul 01, 2020 at 03:53:06PM -0600, Rob Herring wrote:
> > If guests don't have certain CPU erratum work-arounds implemented, then
> > there is a possibility a guest can deadlock the system. IOW, only trusted
> > guests should be used on systems with the erratum.
> >
> > This is the case for Cortex-A57 erratum 832075.
> >
> > Cc: Marc Zyngier <maz@kernel.org>
> > Cc: James Morse <james.morse@arm.com>
> > Cc: Julien Thierry <julien.thierry.kdev@gmail.com>
> > Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
> > Cc: Catalin Marinas <catalin.marinas@arm.com>
> > Cc: Will Deacon <will@kernel.org>
> > Cc: kvmarm@lists.cs.columbia.edu
> > Signed-off-by: Rob Herring <robh@kernel.org>
> > ---
> >  arch/arm64/kvm/arm.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> > index 90cb90561446..e2f50fa4d825 100644
> > --- a/arch/arm64/kvm/arm.c
> > +++ b/arch/arm64/kvm/arm.c
> > @@ -1653,6 +1653,10 @@ int kvm_arch_init(void *opaque)
> >               return -ENODEV;
> >       }
> >
> > +     if (cpus_have_const_cap(ARM64_WORKAROUND_DEVICE_LOAD_ACQUIRE))
> > +             kvm_info("Guests without required CPU erratum work-arounds can deadlock system!\n" \
>
> work-arounds => workarounds
>
> (mainly for consistency, I have no clue if this is a real word or not!).
>
> I'd also probably do erratum => errata given that you're about to add a
> second one.

Humm, the plural is on workarounds. If I use a more standard singular
vs. plural form like "CPU feature workarounds" vs "CPU features
workarounds", the former seems more correct to me. (working around
features may be a bit nonsensical, but big.LITTLE ;) )

Rob
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