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;

?

Thanks.

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