Revert "KVM: X86: Update mmu->pdptrs only when it is changed"

This reverts commit 24cd19a2.
Sean Christopherson reports:

"Commit 24cd19a2 ('KVM: X86: Update mmu->pdptrs only when it is
changed') breaks nested VMs with EPT in L0 and PAE shadow paging in L2.
Reproducing is trivial, just disable EPT in L1 and run a VM.  I haven't
investigating how it breaks things."
Reviewed-by: NSean Christopherson <seanjc@google.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/x86.c

@@ -841,12 +841,9 @@ int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3)
 		}
 	}
 
-	kvm_register_mark_available(vcpu, VCPU_EXREG_PDPTR);
-	if (memcmp(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs))) {
-		memcpy(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs));
-		kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);
-		kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu);
-	}
+	memcpy(mmu->pdptrs, pdpte, sizeof(mmu->pdptrs));
+	kvm_register_mark_dirty(vcpu, VCPU_EXREG_PDPTR);
+	kvm_make_request(KVM_REQ_LOAD_MMU_PGD, vcpu);
 	vcpu->arch.pdptrs_from_userspace = false;
 
 	return 1;