From: Oliver Upton <oliver.upton@linux.dev>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>,
linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
Will Deacon <will@kernel.org>, James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>
Subject: Re: [PATCH] arm64: Fix early handling of FEAT_E2H0 not being implemented
Date: Thu, 21 Mar 2024 16:34:40 -0700 [thread overview]
Message-ID: <ZfzEEObU-mmZF9_l@linux.dev> (raw)
In-Reply-To: <ZfyVj8txU6WngPGH@arm.com>
On Thu, Mar 21, 2024 at 08:16:15PM +0000, Catalin Marinas wrote:
> On Thu, Mar 21, 2024 at 11:54:14AM +0000, Marc Zyngier wrote:
> > Commit 3944382fa6f2 introduced checks for the FEAT_E2H0 not being
> > implemented. However, the check is absolutely wrong and makes a
> > point it testing a bit that is guaranteed to be zero.
> >
> > On top of that, the detection happens way too late, after the
> > init_el2_state has done its job.
> >
> > This went undetected because the HW this was tested on has E2H being
> > RAO/WI, and not RES1. However, the bug shows up when run as a nested
> > guest, where HCR_EL2.E2H is not necessarily set to 1. As a result,
> > booting the kernel in hVHE mode fails with timer accesses being
> > cought in a trap loop (which was fun to debug).
> >
> > Fix the check for ID_AA64MMFR4_EL1.E2H0, and set the HCR_EL2.E2H bit
> > early so that it can be checked by the rest of the init sequence.
> >
> > With this, hVHE works again in a NV environment that doesn't have
> > FEAT_E2H0.
> >
> > Fixes: 3944382fa6f2 ("arm64: Treat HCR_EL2.E2H as RES1 when ID_AA64MMFR4_EL1.E2H0 is negative")
> > Signed-off-by: Marc Zyngier <maz@kernel.org>
>
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Thanks!
> I assume Oliver will take it, otherwise I can pick it up after -rc1
> since I don't have the fixed commit in my tree.
I'll pick it up but wont be sending anything out until -rc1.
--
Thanks,
Oliver
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next prev parent reply other threads:[~2024-03-21 23:35 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-21 11:54 [PATCH] arm64: Fix early handling of FEAT_E2H0 not being implemented Marc Zyngier
2024-03-21 20:16 ` Catalin Marinas
2024-03-21 23:34 ` Oliver Upton [this message]
2024-04-01 8:46 ` Oliver Upton
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