linux-kernel - Re: [PATCH v2] arm64: KVM: define ESR_ELx_EC

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Message-ID: <86tten7dx8.wl-maz@kernel.org>
Date: Tue, 10 Sep 2024 15:59:15 +0100
From: Marc Zyngier <maz@...nel.org>
To: Will Deacon <will@...nel.org>
Cc: Catalin Marinas <catalin.marinas@....com>,
	Anastasia Belova <abelova@...ralinux.ru>,
	Oliver Upton <oliver.upton@...ux.dev>,
	James Morse <james.morse@....com>,
	Suzuki K Poulose <suzuki.poulose@....com>,
	Zenghui Yu <yuzenghui@...wei.com>,
	linux-arm-kernel@...ts.infradead.org,
	kvmarm@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	lvc-project@...uxtesting.org,
	stable@...r.kernel.org
Subject: Re: [PATCH v2] arm64: KVM: define ESR_ELx_EC_* constants as UL

On Tue, 10 Sep 2024 10:47:46 +0100,
Will Deacon <will@...nel.org> wrote:
> 
> On Tue, Sep 10, 2024 at 10:08:49AM +0100, Marc Zyngier wrote:
> > On Tue, 10 Sep 2024 09:50:16 +0100,
> > Anastasia Belova <abelova@...ralinux.ru> wrote:
> > > 
> > > Add explicit casting to prevent expantion of 32th bit of
> > > u32 into highest half of u64 in several places.
> > > 
> > > For example, in inject_abt64:
> > > ESR_ELx_EC_DABT_LOW << ESR_ELx_EC_SHIFT = 0x24 << 26.
> > > This operation's result is int with 1 in 32th bit.
> > > While casting this value into u64 (esr is u64) 1
> > > fills 32 highest bits.
> > > 
> > > Found by Linux Verification Center (linuxtesting.org) with SVACE.
> > > 
> > > Fixes: aa8eff9bfbd5 ("arm64: KVM: fault injection into a guest")
> > > Signed-off-by: Anastasia Belova <abelova@...ralinux.ru>
> > 
> > nit: the subject line is misleading, as this doesn't only affect KVM,
> > but the whole of the arm64 port (the exception classes form a generic
> > architectural construct).
> 
> Weird, this v2 landed in my spam for some reason.
> 
> > This also probably deserve a Cc stable.
> > 
> > Will, Catalin: I'm happy to queue this in the KVM tree, but if you are
> > taking it directly:
> > 
> > Acked-by: Marc Zyngier <maz@...nel.org>
> 
> 
> I can take it via arm64. I assume it's ok to land in v6.12 (with the cc:
> stable), or is there an urgency to landing this in v6.11? It looks it
> was found using verification tools, rather than because of an actual
> issue affecting users.

Yup, 6.12 is just fine. It would only affect ESR encodings that have
an ISS2 in the top 32 bits, and that's only a very small number of
features, most of which don't exist in HW yet.

Thanks,

	M.

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