From mboxrd@z Thu Jan  1 00:00:00 1970
From: Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>
Subject: Re: [PATCH 7/8] KVM: x86: avoid logical_map when it is invalid
Date: Fri, 30 Jan 2015 15:21:05 +0100
Message-ID: <20150130142105.GA27414@potion.redhat.com>
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Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
	Nadav Amit <namit@cs.technion.ac.il>,
	Gleb Natapov <gleb@kernel.org>
To: Paolo Bonzini <pbonzini@redhat.com>
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2015-01-30 10:19+0100, Paolo Bonzini:
> On 29/01/2015 22:48, Radim Kr=C4=8Dm=C3=A1=C5=99 wrote:
> > We want to support mixed modes and the easiest solution is to avoid
> > optimizing those weird and unlikely scenarios.
>=20
> Hmm, what happens if use maxcpus to disable some CPUs at startup?

Their APICs are kept sw-disabled in xAPIC mode.

>                                                                    Co=
uld
> the disabled CPUs remain in xapic mode while the others move to x2api=
c?

Yes, but it would only matter if the OS set LDR on them.
I mark x2APIC with perfectly configured xAPIC on unused processors as
"weird" ... (Linux 3.18 and 2.6.32 doesn't do it.)