From: Paul Mackerras <paulus@samba.org>
To: Alexander Graf <agraf@suse.de>
Cc: kvm-ppc@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH v2] KVM: PPC: Book3s PR: Disable AIL mode with OPAL
Date: Tue, 17 Jun 2014 20:15:57 +1000 [thread overview]
Message-ID: <20140617101557.GA8790@iris.ozlabs.ibm.com> (raw)
In-Reply-To: <1402999438-51617-1-git-send-email-agraf@suse.de>
On Tue, Jun 17, 2014 at 12:03:58PM +0200, Alexander Graf wrote:
> When we're using PR KVM we must not allow the CPU to take interrupts
> in virtual mode, as the SLB does not contain host kernel mappings
> when running inside the guest context.
>
> To make sure we get good performance for non-KVM tasks but still
> properly functioning PR KVM, let's just disable AIL whenever a vcpu
> is scheduled in.
>
> This is fundamentally different from how we deal with AIL on pSeries
> type machines where we disable AIL for the whole machine as soon as
> a single KVM VM is up.
>
> The reason for that is easy - on pSeries we do not have control over
> per-cpu configuration of AIL. We also don't want to mess with CPU hotplug
> races and AIL configuration, so setting it per CPU is easier and more
> flexible.
>
> This patch fixes running PR KVM on POWER8 bare metal for me.
>
> Signed-off-by: Alexander Graf <agraf@suse.de>
Acked-by: Paul Mackerras <paulus@samba.org>
prev parent reply other threads:[~2014-06-17 10:16 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-17 10:03 [PATCH v2] KVM: PPC: Book3s PR: Disable AIL mode with OPAL Alexander Graf
2014-06-17 10:15 ` Paul Mackerras [this message]
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