KVM: x86: Reload pit counters for all channels when restoring state

Currently if userspace restores the pit counters with a count of 0
on channels 1 or 2 and the guest attempts to read the count on those
channels, then KVM will perform a mod of 0 and crash.  This will ensure
that 0 values are converted to 65536 as per the spec.

This is CVE-2015-7513.

Signed-off-by: Andy Honig <ahonig@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
{
	int r;

	kvm_vcpu_mtrr_init(vcpu);
	r = vcpu_load(vcpu);
	if (r)
		return r;
	kvm_vcpu_reset(vcpu, false);
	kvm_mmu_setup(vcpu);
	vcpu_put(vcpu);
	return r;
}

int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
{
	int r;

	kvm_vcpu_mtrr_init(vcpu);
	r = vcpu_load(vcpu);
	if (r)
		return r;
	kvm_vcpu_reset(vcpu, false);
	kvm_mmu_setup(vcpu);
	vcpu_put(vcpu);
	return r;
}
