From: Will Deacon <will@kernel.org>
To: Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
Hector Martin <marcan@marcan.st>, Arnd Bergmann <arnd@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
kernel-team@android.com
Subject: Re: [PATCH v2 2/3] arm64: Cope with CPUs stuck in VHE mode
Date: Wed, 7 Apr 2021 22:16:38 +0100 [thread overview]
Message-ID: <20210407211637.GD16198@willie-the-truck> (raw)
In-Reply-To: <20210330173947.999859-3-maz@kernel.org>
On Tue, Mar 30, 2021 at 06:39:46PM +0100, Marc Zyngier wrote:
> It seems that the CPUs part of the SoC known as Apple M1 have the
> terrible habit of being stuck with HCR_EL2.E2H==1, in violation
> of the architecture.
>
> Try and work around this deplorable state of affairs by detecting
> the stuck bit early and short-circuit the nVHE dance. Additional
> filtering code ensures that attempts at switching to nVHE from
> the command-line are also ignored.
>
> It is still unknown whether there are many more such nuggets
> to be found...
>
> Reported-by: Hector Martin <marcan@marcan.st>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
> arch/arm64/kernel/head.S | 39 +++++++++++++++++++++++++++---
> arch/arm64/kernel/hyp-stub.S | 8 +++---
> arch/arm64/kernel/idreg-override.c | 13 +++++++++-
> 3 files changed, 52 insertions(+), 8 deletions(-)
Acked-by: Will Deacon <will@kernel.org>
Will
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next prev parent reply other threads:[~2021-04-07 21:18 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-30 17:39 [PATCH v2 0/3] arm64: Dealing with VHE-only CPUs Marc Zyngier
2021-03-30 17:39 ` [PATCH v2 1/3] arm64: cpufeature: Allow early filtering of feature override Marc Zyngier
2021-04-08 11:13 ` Hector Martin
2021-04-08 13:11 ` Marc Zyngier
2021-03-30 17:39 ` [PATCH v2 2/3] arm64: Cope with CPUs stuck in VHE mode Marc Zyngier
2021-04-07 21:16 ` Will Deacon [this message]
2021-03-30 17:39 ` [PATCH v2 3/3] arm64: Allow nVHE impaired CPUs to boot without CONFIG_ARM64_VHE Marc Zyngier
2021-04-07 21:18 ` Will Deacon
2021-04-08 10:31 ` Marc Zyngier
2021-04-08 10:58 ` Will Deacon
2021-04-08 13:05 ` Marc Zyngier
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