From mboxrd@z Thu Jan  1 00:00:00 1970
From: Christian Borntraeger <borntraeger@de.ibm.com>
Date: Mon, 27 Sep 2021 07:22:49 +0000
Subject: disabling halt polling broken? (was Re: [PATCH 00/14] KVM: Halt-polling fixes, cleanups and a new st
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To: Sean Christopherson <seanjc@google.com>, Paolo Bonzini <pbonzini@redhat.com>, David Matlack <dmatlack@google.com>, Jon Cargille <jcargill@google.com>, Jim Mattson <jmattson@google.com>
Cc: Huacai Chen <chenhuacai@kernel.org>, Wanpeng Li <wanpengli@tencent.com>, Janosch Frank <frankja@linux.ibm.com>, kvm@vger.kernel.org, David Hildenbrand <david@redhat.com>, Marc Zyngier <maz@kernel.org>, Joerg Roedel <joro@8bytes.org>, Cornelia Huck <cohuck@redhat.com>, linux-mips@vger.kernel.org, kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org, Paul Mackerras <paulus@ozlabs.org>, Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>, linux-arm-kernel@lists.infradead.org, Vitaly Kuznetsov <vkuznets@redhat.com>, Claudio Imbrenda <imbrenda@linux.ibm.com>, kvmarm@lists.cs.columbia.edu

While looking into this series,

I realized that Davids patch

commit acd05785e48c01edb2c4f4d014d28478b5f19fb5
Author:     David Matlack <dmatlack@google.com>
AuthorDate: Fri Apr 17 15:14:46 2020 -0700
Commit:     Paolo Bonzini <pbonzini@redhat.com>
CommitDate: Fri Apr 24 12:53:17 2020 -0400

     kvm: add capability for halt polling

broke the possibility for an admin to disable halt polling for already running KVM guests.
In past times doing
echo 0 > /sys/module/kvm/parameters/halt_poll_ns

stopped polling system wide.
Now all KVM guests will use the halt_poll_ns value that was active during startup - even those that do not use KVM_CAP_HALT_POLL.

I guess this was not intended?