path: root/kernel
diff options
authorThomas Gleixner <>2014-04-24 09:50:53 +0200
committerThomas Gleixner <>2014-04-28 12:20:00 +0200
commit62a08ae2a5763aabeee98264605236b001503e0c (patch)
tree9de35dba4bfaaece70e0963b0ef0d8845ae1b134 /kernel
parentdef5f1273c5f18abf8fcaee03a115d3e907ad407 (diff)
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: Signed-off-by: Thomas Gleixner <>
Diffstat (limited to 'kernel')
2 files changed, 12 insertions, 0 deletions
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index a7174617..bb07f29 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);
diff --git a/kernel/softirq.c b/kernel/softirq.c
index b50990a..33e4648 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;