From: Leo Yan <leo.yan@linaro.org>
To: Marc Zyngier <marc.zyngier@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will.deacon@arm.com>,
Christoffer Dall <christoffer.dall@arm.com>,
linux-kernel@vger.kernel.org, Jun Yao <yaojun8558363@gmail.com>,
James Morse <james.morse@arm.com>,
Andre Przywara <andre.przywara@arm.com>,
Paolo Bonzini <pbonzini@redhat.com>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v1 2/4] KVM: arm/arm64: vgic: Improve comment on kvm_vgic_inject_irq
Date: Mon, 25 Feb 2019 08:09:17 +0800 [thread overview]
Message-ID: <20190225000917.GA4001@leoy-ThinkPad-X240s> (raw)
In-Reply-To: <86r2bzrful.wl-marc.zyngier@arm.com>
On Fri, Feb 22, 2019 at 03:40:50PM +0000, Marc Zyngier wrote:
[...]
> > > The interrupt affinity is either defined by the distributor
> > > configuration (SPIs) or the ITS configuration (LPIs).
> >
> > Given to the up example, I am struggling to understand how you can set
> > the interrupt affinity for virtio device.
> >
> > Do you set the physical interrupt affinity to CPU0/1 in host OS and
> > forward it to guest OS? Or set interrupt affinity in guest OS (I
> > tried on Juno board to set irq affinity in guest OS from
> > '/proc/irq/xxx/smp_affinity' but failed)? Or this is accomplished by
> > user space tool (lkvm or qemu)?
>
> virtio interrupts are purely virtual, and the host plays no part in
> their routing (nor does userspace). As for their affinity, that
> depends on the virtio driver. Some virtio devices allow their affinity
> to be changed, some don't. Here, this is a virtio-net device, which is
> perfectly happy to see its queue interrupts moved to a different vcpu.
>
> I tend to run irqbalance in my guests so that it actually exercises
> the affinity setting in the background.
>
> > Sorry if I am asking a stupid question :)
>
> It's not stupid. You're simply confusing multiple independent layers.
Thanks a lot for explaination, Marc.
Thanks,
Leo Yan
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next prev parent reply other threads:[~2019-02-25 0:09 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-22 8:23 [PATCH v1 0/4] ARM64/KVM: Minor cleanup and refactoring Leo Yan
2019-02-22 8:23 ` [PATCH v1 1/4] KVM: arm64: Use macro to replace hard number Leo Yan
2019-02-22 11:40 ` Mark Rutland
2019-02-22 8:23 ` [PATCH v1 2/4] KVM: arm/arm64: vgic: Improve comment on kvm_vgic_inject_irq Leo Yan
2019-02-22 8:37 ` Marc Zyngier
2019-02-22 8:54 ` Leo Yan
2019-02-22 9:39 ` Marc Zyngier
2019-02-22 12:49 ` Leo Yan
2019-02-22 15:40 ` Marc Zyngier
2019-02-25 0:09 ` Leo Yan [this message]
2019-02-22 8:23 ` [PATCH v1 3/4] KVM: arm/arm64: Define TCR_EL2_T0SZ_MASK as TCR_T0SZ_MASK Leo Yan
2019-02-22 11:43 ` Mark Rutland
2019-02-22 8:23 ` [PATCH v1 4/4] KVM: arm/arm64: Fix comment on create_hyp_mappings() Leo Yan
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