linux-kernel - Re: [PATCH] KVM: arm/arm64: Set ICH_HCR

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Message-ID: <09a615e5-9dce-d194-6290-b8897abd5d12@arm.com>
Date:   Wed, 13 Mar 2019 16:31:05 +0000
From:   Marc Zyngier <marc.zyngier@....com>
To:     Shameerali Kolothum Thodi <shameerali.kolothum.thodi@...wei.com>,
        "Tangnianyao (ICT)" <tangnianyao@...wei.com>,
        Christoffer Dall <christoffer.dall@....com>,
        "james.morse@....com" <james.morse@....com>,
        "julien.thierry@....com" <julien.thierry@....com>,
        "suzuki.poulose@....com" <suzuki.poulose@....com>,
        "catalin.marinas@....com" <catalin.marinas@....com>,
        "will.deacon@....com" <will.deacon@....com>,
        "alex.bennee@...aro.org" <alex.bennee@...aro.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "andre.przywara@....com" <andre.przywara@....com>,
        Zhangshaokun <zhangshaokun@...ilicon.com>,
        "keescook@...omium.org" <keescook@...omium.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "kvmarm@...ts.cs.columbia.edu" <kvmarm@...ts.cs.columbia.edu>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:     Linuxarm <linuxarm@...wei.com>
Subject: Re: [PATCH] KVM: arm/arm64: Set ICH_HCR_EN in guest anyway when using
 gicv4

On 13/03/2019 15:59, Shameerali Kolothum Thodi wrote:

Hi Shameer,

>> Can you please give the following patch a go? I can't test it, but hopefully
>> you can.
> 
> Thanks for your quick response. I just did a quick test on one of our platforms
> with VHE+GICv4 and it seems to fix the performance issue we were seeing
> when GICv4 is enabled.
> 
> Test setup:
> 
> Host connected to a PC over a 10G port.
> Launch Guest with an assigned vf dev.
> Run iperf from Guest,
> 
> 5.0 kernel:
> [ ID]  Interval       Transfer     Bandwidth
> [  3]  0.0-10.0 sec  1.30 GBytes  1.12 Gbits/sec
> 
> +Patch:
> 
> [ ID] 	Interval       Transfer     Bandwidth
> [  3]  0.0-10.0 sec  10.9 GBytes  9.39 Gbits/sec

Ah, that looks much better! I'll try to write it properly, as I think
what we have today is slightly bizarre (we write ICH_HCR_EL2 from too
many paths, and I need to remember how the whole thing works).

Thanks,

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