linux-kernel - Re: [PATCH v4 4/5] arm64: Verify CPU errata work arounds on hotplugged CPU

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Message-ID: <20160422134053.GL2998@e104818-lin.cambridge.arm.com>
Date:	Fri, 22 Apr 2016 14:40:53 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Suzuki K Poulose <suzuki.poulose@....com>
Cc:	linux-arm-kernel@...ts.infradead.org, mark.rutland@....com,
	marc.zyngier@....com, will.deacon@....com,
	linux-kernel@...r.kernel.org,
	Andre Przywara <andre.przywara@....com>,
	Vadim.Lomovtsev@...iumnetworks.com
Subject: Re: [PATCH v4 4/5] arm64: Verify CPU errata work arounds on
 hotplugged CPU

On Fri, Apr 22, 2016 at 12:25:34PM +0100, Suzuki K. Poulose wrote:
> CPU Errata work arounds are detected and applied to the
> kernel code at boot time and the data is then freed up.
> If a new hotplugged CPU requires a work around which
> was not applied at boot time, there is nothing we can
> do but simply fail the booting.
> 
> Cc: Will Deacon <will.deacon@....com>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Andre Przywara <andre.przywara@....com>
> Cc: Catalin Marinas <catalin.marinas@....com>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>

I think Will commented on this previously. Was a decision made to leave
this patch as it is and subsequently add support for enabling local
workarounds for hot-plugged CPUs? I'm fine with this given that most
per-CPU workarounds like undocumented bits are set by firmware. But I'd
like to see it done properly once we have a workaround that needs
per-CPU enabling.

Reviewed-by: Catalin Marinas <catalin.marinas@....com>