From: Sebastian Ott <sebott@linux.ibm.com>
Date: Tue, 26 Feb 2019 16:07:32 +0100
Subject: s390/pci: add parameter to force floating irqs
Git-commit: fbfe07d440f2c55070a0358f66560bb4f9fb92e7
Patch-mainline: v5.2-rc1
References: jsc#SLE-5789 FATE#327042 bsc#1134730 LTC#173388

Provide a kernel parameter to force the usage of floating interrupts.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 Documentation/admin-guide/kernel-parameters.txt |    1 +
 arch/s390/include/asm/pci.h                     |    1 +
 arch/s390/pci/pci.c                             |    5 +++++
 arch/s390/pci/pci_irq.c                         |    3 +++
 4 files changed, 10 insertions(+)

--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3199,6 +3199,7 @@
 				Adding the window is slightly risky (it may
 				conflict with unreported devices), so this
 				taints the kernel.
+		force_floating	[S390] Force usage of floating interrupts.
 
 	pcie_aspm=	[PCIE] Forcibly enable or disable PCIe Active State Power
 			Management.
--- a/arch/s390/include/asm/pci.h
+++ b/arch/s390/include/asm/pci.h
@@ -157,6 +157,7 @@ static inline bool zdev_enabled(struct z
 }
 
 extern const struct attribute_group *zpci_attr_groups[];
+extern unsigned int s390_pci_force_floating __initdata;
 
 /* -----------------------------------------------------------------------------
   Prototypes
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -714,6 +714,7 @@ static void zpci_mem_exit(void)
 }
 
 static unsigned int s390_pci_probe __initdata = 1;
+unsigned int s390_pci_force_floating __initdata;
 static unsigned int s390_pci_initialized;
 
 char * __init pcibios_setup(char *str)
@@ -722,6 +723,10 @@ char * __init pcibios_setup(char *str)
 		s390_pci_probe = 0;
 		return NULL;
 	}
+	if (!strcmp(str, "force_floating")) {
+		s390_pci_force_floating = 1;
+		return NULL;
+	}
 	return str;
 }
 
--- a/arch/s390/pci/pci_irq.c
+++ b/arch/s390/pci/pci_irq.c
@@ -433,6 +433,9 @@ int __init zpci_irq_init(void)
 	int rc;
 
 	irq_delivery = sclp.has_dirq ? DIRECTED : FLOATING;
+	if (s390_pci_force_floating)
+		irq_delivery = FLOATING;
+
 	if (irq_delivery == DIRECTED)
 		zpci_airq.handler = zpci_directed_irq_handler;