KVM: s390: Fixes for 4.19

- more fallout from the hugetlbfs enablement
 - bugfix for vma handling
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Merge tag 'kvm-s390-master-4.19-2' of git://git.kernel.org/pub/scm/linux/kernel/git/kvms390/linux into HEAD

KVM: s390: Fixes for 4.19

- more fallout from the hugetlbfs enablement
- bugfix for vma handling

Documentation/virtual/kvm/api.txt

@@ -4510,7 +4510,8 @@ Do not enable KVM_FEATURE_PV_UNHALT if you disable HLT exits.
 Architectures: s390
 Parameters: none
 Returns: 0 on success, -EINVAL if hpage module parameter was not set
-	 or cmma is enabled
+	 or cmma is enabled, or the VM has the KVM_VM_S390_UCONTROL
+	 flag set
 
 With this capability the KVM support for memory backing with 1m pages
 through hugetlbfs can be enabled for a VM. After the capability is

arch/s390/kvm/kvm-s390.c

@@ -481,7 +481,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 		break;
 	case KVM_CAP_S390_HPAGE_1M:
 		r = 0;
-		if (hpage)
+		if (hpage && !kvm_is_ucontrol(kvm))
 			r = 1;
 		break;
 	case KVM_CAP_S390_MEM_OP:
@@ -691,7 +691,7 @@ static int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
 		mutex_lock(&kvm->lock);
 		if (kvm->created_vcpus)
 			r = -EBUSY;
-		else if (!hpage || kvm->arch.use_cmma)
+		else if (!hpage || kvm->arch.use_cmma || kvm_is_ucontrol(kvm))
 			r = -EINVAL;
 		else {
 			r = 0;

arch/s390/mm/gmap.c

@@ -708,11 +708,13 @@ void gmap_discard(struct gmap *gmap, unsigned long from, unsigned long to)
 		vmaddr |= gaddr & ~PMD_MASK;
 		/* Find vma in the parent mm */
 		vma = find_vma(gmap->mm, vmaddr);
+		if (!vma)
+			continue;
 		/*
 		 * We do not discard pages that are backed by
 		 * hugetlbfs, so we don't have to refault them.
 		 */
-		if (vma && is_vm_hugetlb_page(vma))
+		if (is_vm_hugetlb_page(vma))
 			continue;
 		size = min(to - gaddr, PMD_SIZE - (gaddr & ~PMD_MASK));
 		zap_page_range(vma, vmaddr, size);