From: Christian Borntraeger <borntraeger@de.ibm.com>
To: Halil Pasic <pasic@linux.ibm.com>
Cc: Janosch Frank <frankja@linux.ibm.com>,
Michael Mueller <mimu@linux.ibm.com>,
linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
David Hildenbrand <david@redhat.com>,
Claudio Imbrenda <imbrenda@linux.ibm.com>,
Heiko Carstens <hca@linux.ibm.com>,
Vasily Gorbik <gor@linux.ibm.com>,
Alexander Gordeev <agordeev@linux.ibm.com>,
Pierre Morel <pmorel@linux.ibm.com>,
Tony Krowiak <akrowiak@linux.ibm.com>,
Matthew Rosato <mjrosato@linux.ibm.com>,
Niklas Schnelle <schnelle@linux.ibm.com>,
farman@linux.ibm.com, kvm@vger.kernel.org
Subject: Re: [PATCH 3/3] KVM: s390: clear kicked_mask if not idle after set
Date: Tue, 26 Oct 2021 10:52:40 +0200 [thread overview]
Message-ID: <e4e21f7a-ee60-c00a-c8d9-32a6ebe195b7@de.ibm.com> (raw)
In-Reply-To: <20211020095208.5e34679a.pasic@linux.ibm.com>
Am 20.10.21 um 09:52 schrieb Halil Pasic:
> On Tue, 19 Oct 2021 23:35:25 +0200
> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
>
>>> @@ -426,6 +426,7 @@ static void __unset_cpu_idle(struct kvm_vcpu *vcpu)
>>> {
>>> kvm_s390_clear_cpuflags(vcpu, CPUSTAT_WAIT);
>>> clear_bit(vcpu->vcpu_idx, vcpu->kvm->arch.idle_mask);
>>> + clear_bit(vcpu->vcpu_idx, vcpu->kvm->arch.gisa_int.kicked_mask);
>
> BTW, do you know are bit-ops garanteed to be serialized as seen by
> another cpu even when acting on a different byte? I mean
> could the kick_single_vcpu() set the clear of the kicked_mask bit but
> not see the clear of the idle mask?
clear_bit explicitely says.
* This is a relaxed atomic operation (no implied memory barriers).
so if we really need the ordering, then we need to add a barrier.
>
> If that is not true we may need some barriers, or possibly merging the
> two bitmasks like idle bit, kick bit alterating to ensure there
> absolutely ain't no race.
>
next prev parent reply other threads:[~2021-10-26 8:52 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-19 17:53 [PATCH 0/3] fixes for __airqs_kick_single_vcpu() Halil Pasic
2021-10-19 17:53 ` [PATCH 1/3] KVM: s390: clear kicked_mask before sleeping again Halil Pasic
2021-10-19 21:22 ` Christian Borntraeger
2021-10-20 5:35 ` Claudio Imbrenda
2021-10-20 6:03 ` Christian Borntraeger
2021-10-20 6:08 ` Claudio Imbrenda
2021-10-20 8:14 ` Halil Pasic
2021-10-20 10:42 ` Claudio Imbrenda
2021-10-20 8:06 ` Michael Mueller
2021-10-20 10:44 ` Claudio Imbrenda
2021-10-19 17:54 ` [PATCH 2/3] KVM: s390: preserve deliverable_mask in __airqs_kick_single_vcpu Halil Pasic
2021-10-19 21:24 ` Christian Borntraeger
2021-10-20 5:39 ` Claudio Imbrenda
2021-10-20 8:08 ` Michael Mueller
2021-10-19 17:54 ` [PATCH 3/3] KVM: s390: clear kicked_mask if not idle after set Halil Pasic
2021-10-19 21:35 ` Christian Borntraeger
2021-10-20 5:14 ` Christian Borntraeger
2021-10-20 7:52 ` Halil Pasic
2021-10-26 8:52 ` Christian Borntraeger [this message]
2021-10-20 9:48 ` Michael Mueller
2021-10-20 10:31 ` Christian Borntraeger
2021-10-20 10:45 ` Halil Pasic
2021-10-20 10:52 ` Christian Borntraeger
2021-10-20 10:51 ` Michael Mueller
2021-10-20 11:04 ` [PATCH 0/3] fixes for __airqs_kick_single_vcpu() Christian Borntraeger
2021-10-20 12:12 ` Halil Pasic
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