From 56271303808fb86375ec33183d56c21fdeb836ea Mon Sep 17 00:00:00 2001 From: Sebastian Ott Date: Thu, 18 Apr 2019 21:39:06 +0200 Subject: [PATCH] s390/pci: add parameter to disable usage of MIO instructions Allow users to disable usage of MIO instructions by specifying pci=nomio at the kernel command line. Signed-off-by: Sebastian Ott Signed-off-by: Martin Schwidefsky --- Documentation/admin-guide/kernel-parameters.txt | 1 + arch/s390/pci/pci.c | 7 ++++++- 2 files changed, 7 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index abc1b6e305c4..055284c31e37 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -3395,6 +3395,7 @@ this removes isolation between devices and may put more devices in an IOMMU group. force_floating [S390] Force usage of floating interrupts. + nomio [S390] Do not use MIO instructions. pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power Management. diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c index dff8f4526c8d..0ebb7c405a25 100644 --- a/arch/s390/pci/pci.c +++ b/arch/s390/pci/pci.c @@ -850,6 +850,7 @@ static void zpci_mem_exit(void) } static unsigned int s390_pci_probe __initdata = 1; +static unsigned int s390_pci_no_mio __initdata; unsigned int s390_pci_force_floating __initdata; static unsigned int s390_pci_initialized; @@ -859,6 +860,10 @@ char * __init pcibios_setup(char *str) s390_pci_probe = 0; return NULL; } + if (!strcmp(str, "nomio")) { + s390_pci_no_mio = 1; + return NULL; + } if (!strcmp(str, "force_floating")) { s390_pci_force_floating = 1; return NULL; @@ -881,7 +886,7 @@ static int __init pci_base_init(void) if (!test_facility(69) || !test_facility(71)) return 0; - if (test_facility(153)) + if (test_facility(153) && !s390_pci_no_mio) static_branch_enable(&have_mio); rc = zpci_debug_init();