From mboxrd@z Thu Jan 1 00:00:00 1970
From: Pavel Fedin
Subject: RE: [PATCH v4 3/7] KVM: arm/arm64: Fix the documentation
Date: Thu, 08 Oct 2015 09:52:02 +0300
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Sender: kvm-owner@vger.kernel.org
To: 'Christoffer Dall'
Cc: kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, 'Peter Maydell' , 'Marc Zyngier' , 'Andre Przywara'
List-Id: kvmarm@lists.cs.columbia.edu
Hello!
> > --- a/Documentation/virtual/kvm/devices/arm-vgic.txt
> > +++ b/Documentation/virtual/kvm/devices/arm-vgic.txt
> > @@ -44,28 +44,29 @@ Groups:
> > Attributes:
> > The attr field of kvm_device_attr encodes two values:
> > bits: | 63 .... 40 | 39 .. 32 | 31 .... 0 |
> > - values: | reserved | cpu id | offset |
> > + values: | reserved | cpu idx | offset |
>
> why should this be changed to cpu idx?
Because it's index (from 0 to N - 1), and "cpu id" may confuse readers that it should be MPIDR
affinity value. In register access function we do "vcpu = kvm_get_vcpu(dev->kvm, cpuid);" (see here:
http://lxr.free-electrons.com/source/virt/kvm/arm/vgic-v2-emul.c#L664), and kvm_get_vcpu just
indexes the array: http://lxr.free-electrons.com/source/include/linux/kvm_host.h#L427
I decided to change this after http://www.spinics.net/lists/kvm-arm/msg16359.html, Andre clearly
mistook this ID for being affinity value.
Before GICv3 nobody saw the difference because we had only up to 16 CPUs, with IDs from 0 to 15, i.
e. corresponding to indexes.
Kind regards,
Pavel Fedin
Expert Engineer
Samsung Electronics Research center Russia