Re: [PATCH v3 7/9] KVM: arm/arm64: Only clean the dcache on translation fault

Alexander Graf
2018-08-21T13:35:17Z

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.

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

Alex