KVM: s390: pv: Add query dump information

The dump API requires userspace to provide buffers into which we will
store data. The dump information added in this patch tells userspace
how big those buffers need to be.
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Steffen Eiden <seiden@linux.ibm.com>
Link: https://lore.kernel.org/r/20220517163629.3443-6-frankja@linux.ibm.com
Message-Id: <20220517163629.3443-6-frankja@linux.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@linux.ibm.com>

arch/s390/kvm/kvm-s390.c

@@ -2255,6 +2255,17 @@ static ssize_t kvm_s390_handle_pv_info(struct kvm_s390_pv_info *info)
 
 		return len_min;
 	}
+	case KVM_PV_INFO_DUMP: {
+		len_min =  sizeof(info->header) + sizeof(info->dump);
+
+		if (info->header.len_max < len_min)
+			return -EINVAL;
+
+		info->dump.dump_cpu_buffer_len = uv_info.guest_cpu_stor_len;
+		info->dump.dump_config_mem_buffer_per_1m = uv_info.conf_dump_storage_state_len;
+		info->dump.dump_config_finalize_len = uv_info.conf_dump_finalize_len;
+		return len_min;
+	}
 	default:
 		return -EINVAL;
 	}

include/uapi/linux/kvm.h

@@ -1662,6 +1662,13 @@ struct kvm_s390_pv_unp {
 
 enum pv_cmd_info_id {
 	KVM_PV_INFO_VM,
+	KVM_PV_INFO_DUMP,
+};
+
+struct kvm_s390_pv_info_dump {
+	__u64 dump_cpu_buffer_len;
+	__u64 dump_config_mem_buffer_per_1m;
+	__u64 dump_config_finalize_len;
 };
 
 struct kvm_s390_pv_info_vm {
@@ -1681,7 +1688,10 @@ struct kvm_s390_pv_info_header {
 
 struct kvm_s390_pv_info {
 	struct kvm_s390_pv_info_header header;
-	struct kvm_s390_pv_info_vm vm;
+	union {
+		struct kvm_s390_pv_info_dump dump;
+		struct kvm_s390_pv_info_vm vm;
+	};
 };
 
 enum pv_cmd_id {