s390/ipl: Provide has_secure sysfs attribute

Provide an interface for userspace so it can find out if a machine is
capeable of doing secure boot. The interface is, for example, needed for
zipl so it can find out which file format it can/should write to disk.

Signed-off-by: Philipp Rudo <prudo@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/include/asm/sclp.h

@@ -79,6 +79,8 @@ struct sclp_info {
 	unsigned char has_kss : 1;
 	unsigned char has_gisaf : 1;
 	unsigned char has_diag318 : 1;
+	unsigned char has_sipl : 1;
+	unsigned char has_sipl_g2 : 1;
 	unsigned int ibc;
 	unsigned int mtid;
 	unsigned int mtid_cp;

arch/s390/kernel/ipl.c

@@ -283,6 +283,20 @@ static ssize_t ipl_secure_show(struct kobject *kobj,
 static struct kobj_attribute sys_ipl_secure_attr =
 	__ATTR(secure, 0444, ipl_secure_show, NULL);
 
+static ssize_t ipl_has_secure_show(struct kobject *kobj,
+				   struct kobj_attribute *attr, char *page)
+{
+	if (MACHINE_IS_LPAR)
+		return sprintf(page, "%i\n", !!sclp.has_sipl);
+	else if (MACHINE_IS_VM)
+		return sprintf(page, "%i\n", !!sclp.has_sipl_g2);
+	else
+		return sprintf(page, "%i\n", 0);
+}
+
+static struct kobj_attribute sys_ipl_has_secure_attr =
+	__ATTR(has_secure, 0444, ipl_has_secure_show, NULL);
+
 static ssize_t ipl_vm_parm_show(struct kobject *kobj,
 				struct kobj_attribute *attr, char *page)
 {
@@ -379,6 +393,7 @@ static struct attribute *ipl_fcp_attrs[] = {
 	&sys_ipl_fcp_br_lba_attr.attr,
 	&sys_ipl_ccw_loadparm_attr.attr,
 	&sys_ipl_secure_attr.attr,
+	&sys_ipl_has_secure_attr.attr,
 	NULL,
 };
 
@@ -395,6 +410,7 @@ static struct attribute *ipl_ccw_attrs_vm[] = {
 	&sys_ipl_ccw_loadparm_attr.attr,
 	&sys_ipl_vm_parm_attr.attr,
 	&sys_ipl_secure_attr.attr,
+	&sys_ipl_has_secure_attr.attr,
 	NULL,
 };
 
@@ -403,6 +419,7 @@ static struct attribute *ipl_ccw_attrs_lpar[] = {
 	&sys_ipl_device_attr.attr,
 	&sys_ipl_ccw_loadparm_attr.attr,
 	&sys_ipl_secure_attr.attr,
+	&sys_ipl_has_secure_attr.attr,
 	NULL,
 };
 

drivers/s390/char/sclp.h

@@ -197,7 +197,9 @@ struct read_info_sccb {
 	u32	hmfai;			/* 124-127 */
 	u8	_pad_128[134 - 128];	/* 128-133 */
 	u8	byte_134;			/* 134 */
-	u8	_pad_135[4096 - 135];	/* 135-4095 */
+	u8	_pad_135;		/* 135 */
+	u16	cbl;			/* 136-137 */
+	u8	_pad_138[4096 - 138];	/* 138-4095 */
 } __packed __aligned(PAGE_SIZE);
 
 struct read_storage_sccb {

drivers/s390/char/sclp_early.c

@@ -40,6 +40,8 @@ static void __init sclp_early_facilities_detect(struct read_info_sccb *sccb)
 	sclp.has_gisaf = !!(sccb->fac118 & 0x08);
 	sclp.has_hvs = !!(sccb->fac119 & 0x80);
 	sclp.has_kss = !!(sccb->fac98 & 0x01);
+	sclp.has_sipl = !!(sccb->cbl & 0x02);
+	sclp.has_sipl_g2 = !!(sccb->cbl & 0x04);
 	if (sccb->fac85 & 0x02)
 		S390_lowcore.machine_flags |= MACHINE_FLAG_ESOP;
 	if (sccb->fac91 & 0x40)