KVM: s390x: implement KVM_CAP_SET_GUEST_DEBUG2

Define KVM_GUESTDBG_VALID_MASK and use it to implement this capabiity.
Compile tested only.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20210401135451.1004564-6-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/s390/include/asm/kvm_host.h

@@ -701,6 +701,10 @@ struct kvm_hw_bp_info_arch {
 #define guestdbg_exit_pending(vcpu) (guestdbg_enabled(vcpu) && \
 		(vcpu->guest_debug & KVM_GUESTDBG_EXIT_PENDING))
 
+#define KVM_GUESTDBG_VALID_MASK \
+		(KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP |\
+		KVM_GUESTDBG_USE_HW_BP | KVM_GUESTDBG_EXIT_PENDING)
+
 struct kvm_guestdbg_info_arch {
 	unsigned long cr0;
 	unsigned long cr9;

arch/s390/kvm/kvm-s390.c

@@ -550,6 +550,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
 	case KVM_CAP_S390_DIAG318:
 		r = 1;
 		break;
+	case KVM_CAP_SET_GUEST_DEBUG2:
+		r = KVM_GUESTDBG_VALID_MASK;
+		break;
 	case KVM_CAP_S390_HPAGE_1M:
 		r = 0;
 		if (hpage && !kvm_is_ucontrol(kvm))