From: "Russell King (Oracle)" <linux@armlinux•org.uk>
To: Marc Zyngier <maz@kernel•org>
Cc: linux-arm-kernel@lists•infradead.org, kvm@vger•kernel.org,
kvmarm@lists•cs.columbia.edu, James Morse <james.morse@arm•com>,
Suzuki K Poulose <suzuki.poulose@arm•com>,
Alexandru Elisei <alexandru.elisei@arm•com>,
Alexandre Chartre <alexandre.chartre@oracle•com>,
Robin Murphy <robin.murphy@arm•com>,
kernel-team@android•com
Subject: Re: [PATCH 1/3] KVM: arm64: Narrow PMU sysreg reset values to architectural requirements
Date: Tue, 13 Jul 2021 17:15:44 +0100 [thread overview]
Message-ID: <20210713161544.GL22278@shell.armlinux.org.uk> (raw)
In-Reply-To: <87mtqq6w75.wl-maz@kernel.org>
On Tue, Jul 13, 2021 at 04:59:58PM +0100, Marc Zyngier wrote:
> On Tue, 13 Jul 2021 15:39:49 +0100,
> "Russell King (Oracle)" <linux@armlinux•org.uk> wrote:
> >
> > On Tue, Jul 13, 2021 at 02:58:58PM +0100, Marc Zyngier wrote:
> > > +static void reset_pmu_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
> > > +{
> > > + u64 n, mask;
> > > +
> > > + /* No PMU available, any PMU reg may UNDEF... */
> > > + if (!kvm_arm_support_pmu_v3())
> > > + return;
> > > +
> > > + n = read_sysreg(pmcr_el0) >> ARMV8_PMU_PMCR_N_SHIFT;
> > > + n &= ARMV8_PMU_PMCR_N_MASK;
> > > +
> > > + reset_unknown(vcpu, r);
> > > +
> > > + mask = BIT(ARMV8_PMU_CYCLE_IDX);
> > > + if (n)
> > > + mask |= GENMASK(n - 1, 0);
> > > +
> > > + __vcpu_sys_reg(vcpu, r->reg) &= mask;
> >
> > Would this read more logically to structure it as:
> >
> > mask = BIT(ARMV8_PMU_CYCLE_IDX);
> >
> > n = read_sysreg(pmcr_el0) >> ARMV8_PMU_PMCR_N_SHIFT;
> > n &= ARMV8_PMU_PMCR_N_MASK;
> > if (n)
> > mask |= GENMASK(n - 1, 0);
> >
> > reset_unknown(vcpu, r);
> > __vcpu_sys_reg(vcpu, r->reg) &= mask;
> >
> > ?
>
> Yup, that's nicer. Amended locally.
Thanks Marc.
For the whole series:
Acked-by: Russell King (Oracle) <rmk+kernel@armlinux•org.uk>
--
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next prev parent reply other threads:[~2021-07-13 16:17 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-13 13:58 [PATCH 0/3] kvm-arm64: Fix PMU reset values (and more) Marc Zyngier
2021-07-13 13:58 ` [PATCH 1/3] KVM: arm64: Narrow PMU sysreg reset values to architectural requirements Marc Zyngier
2021-07-13 14:39 ` Russell King (Oracle)
2021-07-13 15:59 ` Marc Zyngier
2021-07-13 16:15 ` Russell King (Oracle) [this message]
2021-07-14 15:48 ` Alexandru Elisei
2021-07-15 11:11 ` Marc Zyngier
2021-07-15 11:51 ` Robin Murphy
2021-07-15 12:25 ` Marc Zyngier
2021-07-13 13:58 ` [PATCH 2/3] KVM: arm64: Drop unnecessary masking of PMU registers Marc Zyngier
2021-07-14 16:12 ` Alexandru Elisei
2021-07-13 13:59 ` [PATCH 3/3] KVM: arm64: Disabling disabled PMU counters wastes a lot of time Marc Zyngier
2021-07-14 16:18 ` Alexandru Elisei
2021-07-15 8:34 ` [PATCH 0/3] kvm-arm64: Fix PMU reset values (and more) Alexandre Chartre
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