linux-kernel - Re: [PATCH] arm64: cpufeature: check translation granule size based on kernel config

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Message-ID: <20170518130130.GD25294@leoy-ThinkPad-T440>
Date:   Thu, 18 May 2017 21:01:30 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Suzuki K Poulose <Suzuki.Poulose@....com>
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Mark Rutland <mark.rutland@....com>,
        Marc Zyngier <marc.zyngier@....com>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        James Morse <james.morse@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Guodong Xu <guodong.xu@...aro.org>,
        Haojian Zhuang <haojian.zhuang@...aro.org>,
        Douglas Raillard <douglas.raillard@....com>
Subject: Re: [PATCH] arm64: cpufeature: check translation granule size based
 on kernel config

On Thu, May 18, 2017 at 01:39:12PM +0100, Suzuki K Poulose wrote:

[...]

> >>If we were to suppress the warning (more on that below), we could simply
> >>make this feature a NON_STRICT, since the unsupported CPUs won't boot
> >>with 16K to hit this sanity check.
> >>
> >>However, there is a problem with disabling this warning. If a VM starts
> >>using 16KB page size on a 4K/64K host, the VM could end up in unknown
> >>failures when it switches to an unsupported CPU (after it has booted).
> >>Of course the real fix lies in making the KVM exposing the safe value
> >>for granule support to the VCPUs (which is currently being worked on by
> >>Douglas in Cc). So, when we have that ready, we could make it NON_STRICT
> >>instead of this approach.
> >
> >Thanks for the info :)
> >
> >I will use below patch for production branch temporarily. You could
> 
> Which production branch do you mean above ? Is it something in your intenral
> repository ?

Yeah, I mean Hikey960 branch.

Thanks,
Leo Yan