ACPI, PCI, irq: Do not share PCI IRQ with ISA IRQ
Avoid IRQs occupied by ISA IRQs when allocating IRQs for PCI link devices,
otherwise it may cause interrupt storm due to incompatible pin attributes.
This issue was triggered on a KVM virtual machine, which
1) uses IRQ9 for SCI in high level mode.
2) defines an PCI interrupt link device (LNKS) with IRQ9 as the only
possible irq.
3) has an PCI device referring to link device LNKS.
So it causes interrupt storm when enabling the PCI device because PCI IRQ
works in low level mode.
Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
diff --git a/drivers/acpi/pci_irq.c b/drivers/acpi/pci_irq.c
index 6da0f9b..c933675 100644
--- a/drivers/acpi/pci_irq.c
+++ b/drivers/acpi/pci_irq.c
@@ -372,6 +372,7 @@
/* Interrupt Line values above 0xF are forbidden */
if (dev->irq > 0 && (dev->irq <= 0xF) &&
+ acpi_isa_irq_available(dev->irq) &&
(acpi_isa_irq_to_gsi(dev->irq, &dev_gsi) == 0)) {
dev_warn(&dev->dev, "PCI INT %c: no GSI - using ISA IRQ %d\n",
pin_name(dev->pin), dev->irq);