linux-kernel - Re: [PATCH] KVM: arm64: Allow PSCI SYSTEM

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Message-ID: <20201229170412.GN1551@shell.armlinux.org.uk>
Date:   Tue, 29 Dec 2020 17:04:12 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     David Brazdil <dbrazdil@...gle.com>
Cc:     kvmarm@...ts.cs.columbia.edu, Mark Rutland <mark.rutland@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Marc Zyngier <maz@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        linux-kernel@...r.kernel.org, James Morse <james.morse@....com>,
        linux-arm-kernel@...ts.infradead.org,
        Catalin Marinas <catalin.marinas@....com>,
        kernel-team@...roid.com, Will Deacon <will@...nel.org>,
        Julien Thierry <julien.thierry.kdev@...il.com>
Subject: Re: [PATCH] KVM: arm64: Allow PSCI SYSTEM_OFF/RESET to return

On Tue, Dec 29, 2020 at 04:00:59PM +0000, David Brazdil wrote:
> The KVM/arm64 PSCI relay assumes that SYSTEM_OFF and SYSTEM_RESET should
> not return, as dictated by the PSCI spec. However, there is firmware out
> there which breaks this assumption, leading to a hyp panic. Make KVM
> more robust to broken firmware by allowing these to return.

Are you sure you should just return?

We've had issues in the past with Linux reboot(2) that returns
to userspace, allowing on 32-bit ARM for example watchdogs to
unexpectedly continue being serviced.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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