From mboxrd@z Thu Jan  1 00:00:00 1970
From: Marc Zyngier <marc.zyngier@arm.com>
Subject: Re: [PATCH v3 7/9] KVM: arm/arm64: Only clean the dcache on
 translation fault
Date: Tue, 21 Aug 2018 14:57:31 +0100
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To: Alexander Graf <agraf@suse.de>, Christoffer Dall <christoffer.dall@linaro.org>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>
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On 21/08/18 14:35, Alexander Graf wrote:
> On 10/23/2017 06:11 PM, Marc Zyngier wrote:
>> The only case where we actually need to perform a dcache maintenance
>> is when we map the page for the first time, and subsequent permission
>> faults do not require cache maintenance. Let's make it conditional
>> on not being a permission fault (and thus a translation fault).
>>
>> Reviewed-by: Christoffer Dall <christoffer.dall@linaro.org>
>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> 
> This patch unfortunately breaks something on Hi1616 SoCs when running 
> 32bit guests. With this patch applied (and thus with 4.18) I get random 
> illegal instruction warnings from 32bit code inside VMs. I do not know 
> at this point whether this affects other CPUs as well.

Can you please give a few more details?

- what are the CPUs on this Hi1616? At least a /proc/cpuinfo would help

- an example of the crash? Is it within the decompressor? After? This
things do matter, given the number of crazy things the 32bit kernel does

- a host kernel configuration?

> If anyone is interested in a reproducer, I have something handy. But for 
> now I believe we should just revert this patch.

Before we revert anything, I'd like to understand what is happening.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...