From 833b441ec0f6f3c57cc2106ef628bb19d8fb0ee2 Mon Sep 17 00:00:00 2001
From: Sebastian Ott <sebott@linux.ibm.com>
Date: Tue, 23 Apr 2019 13:14:28 +0200
Subject: s390: enable processes for mio instructions

Allow for userspace to use PCI MIO instructions.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
---
 arch/s390/include/asm/pci_insn.h | 10 ++++++++++
 arch/s390/kernel/early.c         |  2 ++
 2 files changed, 12 insertions(+)

diff --git a/arch/s390/include/asm/pci_insn.h b/arch/s390/include/asm/pci_insn.h
index 61cf9531f68f..ff81ed19c506 100644
--- a/arch/s390/include/asm/pci_insn.h
+++ b/arch/s390/include/asm/pci_insn.h
@@ -143,4 +143,14 @@ static inline int zpci_set_irq_ctrl(u16 ctl, u8 isc)
 	return __zpci_set_irq_ctrl(ctl, isc, &iib);
 }
 
+#ifdef CONFIG_PCI
+static inline void enable_mio_ctl(void)
+{
+	if (static_branch_likely(&have_mio))
+		__ctl_set_bit(2, 5);
+}
+#else /* CONFIG_PCI */
+static inline void enable_mio_ctl(void) {}
+#endif /* CONFIG_PCI */
+
 #endif
diff --git a/arch/s390/kernel/early.c b/arch/s390/kernel/early.c
index c196abda36c7..ab09ada0e930 100644
--- a/arch/s390/kernel/early.c
+++ b/arch/s390/kernel/early.c
@@ -30,6 +30,7 @@
 #include <asm/sclp.h>
 #include <asm/facility.h>
 #include <asm/boot_data.h>
+#include <asm/pci_insn.h>
 #include "entry.h"
 
 /*
@@ -235,6 +236,7 @@ static __init void detect_machine_facilities(void)
 		clock_comparator_max = -1ULL >> 1;
 		__ctl_set_bit(0, 53);
 	}
+	enable_mio_ctl();
 }
 
 static inline void save_vector_registers(void)
-- 
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