On Tue, 13 Jul 2021 15:39:49 +0100,
"Russell King (Oracle)" [off-list ref] wrote:

On Tue, Jul 13, 2021 at 02:58:58PM +0100, Marc Zyngier wrote:

quoted

+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,

	M.

-- 
Without deviation from the norm, progress is not possible.