KVM: MMU: sync root on paravirt TLB flush

The pvmmu TLB flush handler should request a root sync, similarly to
a native read-write CR3.
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: NAvi Kivity <avi@redhat.com>

arch/x86/kvm/mmu.c

@@ -2634,6 +2634,7 @@ static int kvm_pv_mmu_write(struct kvm_vcpu *vcpu,
 static int kvm_pv_mmu_flush_tlb(struct kvm_vcpu *vcpu)
 {
 	kvm_x86_ops->tlb_flush(vcpu);
+	set_bit(KVM_REQ_MMU_SYNC, &vcpu->requests);
 	return 1;
 }