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From: Marc Zyngier <marc.zyngier@arm.com>
To: Alexander Graf <agraf@suse.de>,
	Christoffer Dall <christoffer.dall@linaro.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will.deacon@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org,
	kvmarm@lists.cs.columbia.edu
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	[thread overview]
Message-ID: <9fa7efdf-1c21-7b07-edb9-0c7d0d91eaed@arm.com> (raw)
In-Reply-To: <bfeee11e-f8bf-78f2-ab61-27e43781e2e3@suse.de>

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...

  parent reply	other threads:[~2018-08-21 13:57 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-10-23 16:11 [PATCH v3 0/9] arm/arm64: KVM: limit icache invalidation to prefetch aborts Marc Zyngier
2017-10-23 16:11 ` [PATCH v3 1/9] KVM: arm/arm64: Detangle kvm_mmu.h from kvm_hyp.h Marc Zyngier
2017-10-23 16:11 ` [PATCH v3 2/9] KVM: arm/arm64: Split dcache/icache flushing Marc Zyngier
2017-10-23 16:11 ` [PATCH v3 3/9] arm64: KVM: Add invalidate_icache_range helper Marc Zyngier
2017-10-23 16:19   ` Will Deacon
2017-10-23 16:11 ` [PATCH v3 4/9] arm: KVM: Add optimized PIPT icache flushing Marc Zyngier
2017-10-23 16:11 ` [PATCH v3 5/9] arm64: KVM: PTE/PMD S2 XN bit definition Marc Zyngier
2017-10-23 16:11 ` [PATCH v3 6/9] KVM: arm/arm64: Limit icache invalidation to prefetch aborts Marc Zyngier
2017-11-01 10:17   ` Andrew Jones
2017-11-02 10:36     ` Marc Zyngier
2017-11-02 13:13       ` Andrew Jones
2017-10-23 16:11 ` [PATCH v3 7/9] KVM: arm/arm64: Only clean the dcache on translation fault Marc Zyngier
2018-08-21 13:35   ` Alexander Graf
2018-08-21 13:42     ` Alexander Graf
2018-08-21 13:57     ` Marc Zyngier [this message]
2018-08-21 14:08       ` Alexander Graf
2018-08-21 15:08         ` Marc Zyngier
2018-08-21 16:54           ` Alexander Graf
2018-08-23 11:16             ` Marc Zyngier
2018-08-23 12:24               ` Alexander Graf
2018-08-23 12:43                 ` Marc Zyngier
2018-09-01 10:03                   ` Alexander Graf
2018-08-21 16:45         ` Alexander Graf
2017-10-23 16:11 ` [PATCH v3 8/9] KVM: arm/arm64: Preserve Exec permission across R/W permission faults Marc Zyngier
2017-10-23 16:11 ` [PATCH v3 9/9] KVM: arm/arm64: Drop vcpu parameter from guest cache maintenance operartions Marc Zyngier

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