[PATCH v1 15/26] s390: Add functions to query arm guest time

[Steffen Eiden]

Add functions to convert between ARM guest time (LSB0) and s390 host
time (MSB0) using new ptff function codes.

Co-developed-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
Signed-off-by: Steffen Eiden <seiden@xxxxxxxxxxxxx>
---
 arch/s390/include/asm/timex.h | 49 +++++++++++++++++++++++++++++++++++
 arch/s390/kernel/time.c       |  1 +
 arch/s390/kvm/arm64/arm.c     |  9 ++++++-
 3 files changed, 58 insertions(+), 1 deletion(-)

diff --git a/arch/s390/include/asm/timex.h b/arch/s390/include/asm/timex.h
index 49447b40f038..9ec22a28bbda 100644
--- a/arch/s390/include/asm/timex.h
+++ b/arch/s390/include/asm/timex.h
@@ -99,6 +99,8 @@ extern unsigned char ptff_function_mask[16];
 #define PTFF_QSI	0x02	/* query steering information */
 #define PTFF_QPT	0x03	/* query physical clock */
 #define PTFF_QUI	0x04	/* query UTC information */
+#define PTFF_QAGTO	0x10	/* query arm guest time offset */
+#define PTFF_QAGPT	0x11	/* query arm guest physical time offset */
 #define PTFF_ATO	0x40	/* adjust tod offset */
 #define PTFF_STO	0x41	/* set tod offset */
 #define PTFF_SFS	0x42	/* set fine steering rate */
@@ -136,6 +138,17 @@ struct ptff_qui {
 	unsigned int pad_0x5c[41];
 } __packed;
 
+/*
+ * Query Arm Guest Time
+ * used for:
+ *	- Query Arm Guest Time Offset
+ *	- Query Arm Guest Physical Time
+ */
+struct ptff_qagt {
+	u64 in;
+	u64 out;
+};
+
 /*
  * ptff - Perform timing facility function
  * @ptff_block: Pointer to ptff parameter block
@@ -286,4 +299,40 @@ static inline int tod_after_eq(unsigned long a, unsigned long b)
 	return a >= b;
 }
 
+/*
+ * ptff_qagto() -  Query Arm Guest Time Offset
+ *
+ * @physical_time: Arm guest physical time in MSb 0
+ *
+ * Converts Arm guest physical time in MSb 0 bit ordering
+ * into the Arm guest offset in LSb 0 bit ordering.
+ *
+ * Return: Arm guest time offset in LSb 0
+ */
+static inline u64 ptff_qagto(u64 physical_time)
+{
+	struct ptff_qagt qagto = { .in = physical_time };
+
+	ptff(&qagto, sizeof(qagto), PTFF_QAGTO);
+	return qagto.out;
+}
+
+/*
+ * ptff_qagpt() - Query Arm Guest Physical Time
+ *
+ * @guest_time_offset: Arm guest time offset in MSb 0
+ *
+ * Converts Arm guest offset in MSb 0 bit ordering
+ * into the Arm guest physical time in LSb 0 bit ordering.
+ *
+ * Return: Arm guest physical time in LSb 0
+ * */
+static inline u64 ptff_qagpt(u64 guest_time_offset)
+{
+	struct ptff_qagt qagpt = { .in = guest_time_offset };
+
+	ptff(&qagpt, sizeof(qagpt), PTFF_QAGPT);
+	return qagpt.out;
+}
+
 #endif
diff --git a/arch/s390/kernel/time.c b/arch/s390/kernel/time.c
index bd0df61d1907..2b989bebd220 100644
--- a/arch/s390/kernel/time.c
+++ b/arch/s390/kernel/time.c
@@ -65,6 +65,7 @@ ATOMIC_NOTIFIER_HEAD(s390_epoch_delta_notifier);
 EXPORT_SYMBOL(s390_epoch_delta_notifier);
 
 unsigned char ptff_function_mask[16];
+EXPORT_SYMBOL(ptff_function_mask);
 
 static unsigned long lpar_offset;
 static unsigned long initial_leap_seconds;
diff --git a/arch/s390/kvm/arm64/arm.c b/arch/s390/kvm/arm64/arm.c
index bf0866659421..636bbeda98a8 100644
--- a/arch/s390/kvm/arm64/arm.c
+++ b/arch/s390/kvm/arm64/arm.c
@@ -692,8 +692,15 @@ long kvm_arch_vcpu_unlocked_ioctl(struct file *filp, unsigned int ioctl,
 
 static int __init kvm_s390_arm64_init(void)
 {
-	if (!sclp.has_aef)
+	if (!sclp.has_aef) {
+		pr_info("SAE is not available\n");
 		return -ENXIO;
+	}
+
+	if (!(ptff_query(PTFF_QAGTO) && ptff_query(PTFF_QAGPT))) {
+		pr_info("PTFF for arm on s390 is not available\n");
+		return -ENXIO;
+	}
 
 	return kvm_init_with_dev(sizeof(struct kvm_vcpu), 0, THIS_MODULE,
 				 KVM_DEV_NAME, MISC_DYNAMIC_MINOR);
-- 
2.53.0