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From: Sean Christopherson <seanjc@google.com>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: Sebastian Ott <sebott@redhat.com>,
	kvmarm@lists.linux.dev,  linux-arm-kernel@lists.infradead.org,
	Marc Zyngier <maz@kernel.org>
Subject: Re: [PATCH] KVM: arm64: Fix smp_processor_id() call in preemptible context
Date: Tue, 6 Jun 2023 10:04:13 -0700	[thread overview]
Message-ID: <ZH9nDSPySNFs8tW/@google.com> (raw)
In-Reply-To: <ZH9mOXYDWnMqoL9c@linux.dev>

On Tue, Jun 06, 2023, Oliver Upton wrote:
> On Tue, Jun 06, 2023 at 03:46:09PM +0000, Sean Christopherson wrote:
> > I.e. can't you just do?
> 
> No, this would break the 'old' ABI, but if we decide to deliberately
> break it I prefer your suggestion over using CPU0.

Ah, if userspace pins the task when doing KVM_ARM_VCPU_PMU_V3_CTRL, then factoring
in the pCPU matters.

WARNING: multiple messages have this Message-ID (diff)
From: Sean Christopherson <seanjc@google.com>
To: Oliver Upton <oliver.upton@linux.dev>
Cc: Sebastian Ott <sebott@redhat.com>,
	kvmarm@lists.linux.dev,  linux-arm-kernel@lists.infradead.org,
	Marc Zyngier <maz@kernel.org>
Subject: Re: [PATCH] KVM: arm64: Fix smp_processor_id() call in preemptible context
Date: Tue, 6 Jun 2023 10:04:13 -0700	[thread overview]
Message-ID: <ZH9nDSPySNFs8tW/@google.com> (raw)
In-Reply-To: <ZH9mOXYDWnMqoL9c@linux.dev>

On Tue, Jun 06, 2023, Oliver Upton wrote:
> On Tue, Jun 06, 2023 at 03:46:09PM +0000, Sean Christopherson wrote:
> > I.e. can't you just do?
> 
> No, this would break the 'old' ABI, but if we decide to deliberately
> break it I prefer your suggestion over using CPU0.

Ah, if userspace pins the task when doing KVM_ARM_VCPU_PMU_V3_CTRL, then factoring
in the pCPU matters.

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http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2023-06-06 17:04 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-06 10:37 [PATCH] KVM: arm64: Fix smp_processor_id() call in preemptible context Sebastian Ott
2023-06-06 10:37 ` Sebastian Ott
2023-06-06 13:59 ` Sean Christopherson
2023-06-06 13:59   ` Sean Christopherson
2023-06-06 14:10 ` Oliver Upton
2023-06-06 14:10   ` Oliver Upton
2023-06-06 14:24   ` Sebastian Ott
2023-06-06 14:24     ` Sebastian Ott
2023-06-06 14:29   ` Sean Christopherson
2023-06-06 14:29     ` Sean Christopherson
2023-06-06 15:18     ` Oliver Upton
2023-06-06 15:18       ` Oliver Upton
2023-06-06 15:46       ` Sean Christopherson
2023-06-06 15:46         ` Sean Christopherson
2023-06-06 17:00         ` Oliver Upton
2023-06-06 17:00           ` Oliver Upton
2023-06-06 17:04           ` Sean Christopherson [this message]
2023-06-06 17:04             ` Sean Christopherson
2023-06-06 16:17   ` Marc Zyngier
2023-06-06 16:17     ` Marc Zyngier
2023-06-06 16:48     ` Oliver Upton
2023-06-06 16:48       ` Oliver Upton
2023-06-06 17:10       ` Marc Zyngier
2023-06-06 17:10         ` Marc Zyngier

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