From: Oliver Upton <oliver.upton@linux.dev>
To: Marc Zyngier <maz@kernel.org>
Cc: kvmarm@lists.linux.dev, James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>, Will Deacon <will@kernel.org>
Subject: Re: [PATCH 3/3] KVM: arm64: Do not disable preemption in kvm_vcpu_pmu_restore_guest()
Date: Wed, 6 Mar 2024 01:54:59 -0800 [thread overview]
Message-ID: <Zeg9c15-PAy8pOmV@linux.dev> (raw)
In-Reply-To: <87cys7r8jr.wl-maz@kernel.org>
On Wed, Mar 06, 2024 at 09:52:56AM +0000, Marc Zyngier wrote:
> On Tue, 05 Mar 2024 18:48:40 +0000,
> Oliver Upton <oliver.upton@linux.dev> wrote:
> >
> > The caller has already disabled preemption, no need to nest further.
>
> A quick survey indicates that it doesn't seem to be the case, I'm
> afraid. access_pmu_evtyper() and access_pmcnten() both seem to be
> preemptible.
Dammit. Someone forgot to grep...
> Which probably means that these spots are doing the wrong thing and
> that we should instead turn it into a KVM_REQ_RESYNC_PMU_EL0 request.
>
> Then the preemption can be actually dropped, and even replaced by an
> assertion.
Agreed, thanks for the suggestion.
--
Best,
Oliver
next prev parent reply other threads:[~2024-03-06 9:55 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-05 18:48 [PATCH 0/3] KVM: arm64: PMU fixes for nVHE, protected mode Oliver Upton
2024-03-05 18:48 ` [PATCH 1/3] KVM: arm64: pkvm: Actually enable/disable PMU events when running vCPU Oliver Upton
2024-03-06 10:06 ` Marc Zyngier
2024-03-06 10:18 ` Oliver Upton
2024-03-06 13:23 ` Fuad Tabba
2024-03-05 18:48 ` [PATCH 2/3] KVM: arm64: Fix host-programmed guest events in nVHE Oliver Upton
2024-03-06 9:59 ` Marc Zyngier
2024-03-05 18:48 ` [PATCH 3/3] KVM: arm64: Do not disable preemption in kvm_vcpu_pmu_restore_guest() Oliver Upton
2024-03-06 9:52 ` Marc Zyngier
2024-03-06 9:54 ` Oliver Upton [this message]
2024-03-26 13:44 ` (subset) [PATCH 0/3] KVM: arm64: PMU fixes for nVHE, protected mode Oliver Upton
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