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From:   Oliver Upton <oliver.upton@linux.dev>
To:     Raghavendra Rao Ananta <rananta@google.com>
Cc:     Sebastian Ott <sebott@redhat.com>, Marc Zyngier <maz@kernel.org>,
        Alexandru Elisei <alexandru.elisei@arm.com>,
        James Morse <james.morse@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Zenghui Yu <yuzenghui@huawei.com>,
        Shaoqin Huang <shahuang@redhat.com>,
        Jing Zhang <jingzhangos@google.com>,
        Reiji Watanabe <reijiw@google.com>,
        Colton Lewis <coltonlewis@google.com>,
        linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
        linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: Re: [PATCH v7 07/12] KVM: arm64: PMU: Set PMCR_EL0.N for vCPU based
 on the associated PMU
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On Tue, Oct 17, 2023 at 05:52:24AM +0000, Oliver Upton wrote:
> On Mon, Oct 16, 2023 at 02:35:52PM -0700, Raghavendra Rao Ananta wrote:
> 
> [...]
> 
> > > What's the point of doing this in the first place? The implementation of
> > > kvm_vcpu_read_pmcr() is populating PMCR_EL0.N using the VM-scoped value.
> > >
> > I guess originally the change replaced read_sysreg(pmcr_el0) with
> > kvm_vcpu_read_pmcr(vcpu) to maintain consistency with others.
> > But if you and Sebastian feel that it's an overkill and directly
> > getting the value via vcpu->kvm->arch.pmcr_n is more readable, I'm
> > happy to make the change.
> 
> No, I'd rather you delete the line where PMCR_EL0.N altogether.

... where we set up ...

> reset_pmcr() tries to initialize the field, but your
> kvm_vcpu_read_pmcr() winds up replacing it with pmcr_n.

-- 
Thanks,
Oliver