arm64: KVM: pmu: Fix AArch32 cycle counter access

We're missing the handling code for the cycle counter accessed
from a 32bit guest, leading to unexpected results.

Cc: stable@vger.kernel.org # 4.6+
Signed-off-by: Wei Huang <wei@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
{
	const struct sys_reg_desc *r;
	void __user *uaddr = (void __user *)(unsigned long)reg->addr;

	if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_DEMUX)
		return demux_c15_set(reg->id, uaddr);

	if (KVM_REG_SIZE(reg->id) != sizeof(__u64))
		return -ENOENT;

	r = index_to_sys_reg_desc(vcpu, reg->id);
	if (!r)
		return set_invariant_sys_reg(reg->id, uaddr);

	if (r->set_user)
		return (r->set_user)(vcpu, r, reg, uaddr);

	return reg_from_user(&vcpu_sys_reg(vcpu, r->reg), uaddr, reg->id);
}

int kvm_arm_sys_reg_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
{
	const struct sys_reg_desc *r;
	void __user *uaddr = (void __user *)(unsigned long)reg->addr;

	if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_DEMUX)
		return demux_c15_set(reg->id, uaddr);

	if (KVM_REG_SIZE(reg->id) != sizeof(__u64))
		return -ENOENT;

	r = index_to_sys_reg_desc(vcpu, reg->id);
	if (!r)
		return set_invariant_sys_reg(reg->id, uaddr);

	if (r->set_user)
		return (r->set_user)(vcpu, r, reg, uaddr);

	return reg_from_user(&vcpu_sys_reg(vcpu, r->reg), uaddr, reg->id);
}
