From 62a08ae2a5763aabeee98264605236b001503e0c Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 24 Apr 2014 09:50:53 +0200 Subject: [PATCH] genirq: x86: Ensure that dynamic irq allocation does not conflict On x86 the allocation of irq descriptors may allocate interrupts which are in the range of the GSI interrupts. That's wrong as those interrupts are hardwired and we don't have the irq domain translation like PPC. So one of these interrupts can be hooked up later to one of the devices which are hard wired to it and the io_apic init code for that particular interrupt line happily reuses that descriptor with a completely different configuration so hell breaks lose. Inside x86 we allocate dynamic interrupts from above nr_gsi_irqs, except for a few usage sites which have not yet blown up in our face for whatever reason. But for drivers which need an irq range, like the GPIO drivers, we have no limit in place and we don't want to expose such a detail to a driver. To cure this introduce a function which an architecture can implement to impose a lower bound on the dynamic interrupt allocations. Implement it for x86 and set the lower bound to nr_gsi_irqs, which is the end of the hardwired interrupt space, so all dynamic allocations happen above. That not only allows the GPIO driver to work sanely, it also protects the bogus callsites of create_irq_nr() in hpet, uv, irq_remapping and htirq code. They need to be cleaned up as well, but that's a separate issue. Reported-by: Jin Yao Signed-off-by: Thomas Gleixner Tested-by: Mika Westerberg Cc: Mathias Nyman Cc: Linus Torvalds Cc: Grant Likely Cc: H. Peter Anvin Cc: Rafael J. Wysocki Cc: Andy Shevchenko Cc: Krogerus Heikki Cc: Linus Walleij Link: http://lkml.kernel.org/r/alpine.DEB.2.02.1404241617360.28206@ionos.tec.linutronix.de Signed-off-by: Thomas Gleixner --- arch/x86/kernel/apic/io_apic.c | 5 +++++ include/linux/irq.h | 2 ++ kernel/irq/irqdesc.c | 7 +++++++ kernel/softirq.c | 5 +++++ 4 files changed, 19 insertions(+) diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c index 6ad4658de705..d23aa82e7a7b 100644 --- a/arch/x86/kernel/apic/io_apic.c +++ b/arch/x86/kernel/apic/io_apic.c @@ -3425,6 +3425,11 @@ int get_nr_irqs_gsi(void) return nr_irqs_gsi; } +unsigned int arch_dynirq_lower_bound(unsigned int from) +{ + return from < nr_irqs_gsi ? nr_irqs_gsi : from; +} + int __init arch_probe_nr_irqs(void) { int nr; diff --git a/include/linux/irq.h b/include/linux/irq.h index 10a0b1ac4ea0..5c57efb863d0 100644 --- a/include/linux/irq.h +++ b/include/linux/irq.h @@ -603,6 +603,8 @@ static inline u32 irq_get_trigger_type(unsigned int irq) return d ? irqd_get_trigger_type(d) : 0; } +unsigned int arch_dynirq_lower_bound(unsigned int from); + int __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node, struct module *owner); diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c index a7174617616b..bb07f2928f4b 100644 --- a/kernel/irq/irqdesc.c +++ b/kernel/irq/irqdesc.c @@ -363,6 +363,13 @@ __irq_alloc_descs(int irq, unsigned int from, unsigned int cnt, int node, if (from > irq) return -EINVAL; from = irq; + } else { + /* + * For interrupts which are freely allocated the + * architecture can force a lower bound to the @from + * argument. x86 uses this to exclude the GSI space. + */ + from = arch_dynirq_lower_bound(from); } mutex_lock(&sparse_irq_lock); diff --git a/kernel/softirq.c b/kernel/softirq.c index b50990a5bea0..33e4648ae0e7 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -779,3 +779,8 @@ int __init __weak arch_early_irq_init(void) { return 0; } + +unsigned int __weak arch_dynirq_lower_bound(unsigned int from) +{ + return from; +}