KVM: VMX: Add ept_sync_context in flush_tlb

Fix a potention issue caused by kvm_mmu_slot_remove_write_access(). The
old behavior don't sync EPT TLB with modified EPT entry, which result
in inconsistent content of EPT TLB and EPT table.
Signed-off-by: Sheng Yang <sheng.yang@intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

arch/x86/kvm/vmx.c

@@ -91,6 +91,7 @@ static inline struct vcpu_vmx *to_vmx(struct kvm_vcpu *vcpu)
 }
 
 static int init_rmode(struct kvm *kvm);
+static u64 construct_eptp(unsigned long root_hpa);
 
 static DEFINE_PER_CPU(struct vmcs *, vmxarea);
 static DEFINE_PER_CPU(struct vmcs *, current_vmcs);
@@ -1422,6 +1423,8 @@ static void exit_lmode(struct kvm_vcpu *vcpu)
 static void vmx_flush_tlb(struct kvm_vcpu *vcpu)
 {
 	vpid_sync_vcpu_all(to_vmx(vcpu));
+	if (vm_need_ept())
+		ept_sync_context(construct_eptp(vcpu->arch.mmu.root_hpa));
 }
 
 static void vmx_decache_cr4_guest_bits(struct kvm_vcpu *vcpu)