x86, pci: introduce pci=ioapicreroute kernel cmdline option

Introduce pci=ioapicreroute kernel cmdline option to enable rerouting of boot
interrupts to the primary io-apic.
Signed-off-by: Stefan Assmann <sassmann@suse.de>
Signed-off-by: Olaf Dabrunz <od@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Documentation/kernel-parameters.txt

@@ -1521,6 +1521,10 @@ and is between 256 and 4096 characters. It is defined in the file
 		noioapicquirk	[APIC] Disable all boot interrupt quirks.
 				Safety option to keep boot IRQs enabled. This
 				should never be necessary.
+		ioapicreroute	[APIC] Enable rerouting of boot IRQs to the
+				primary IO-APIC for bridges that cannot disable
+				boot IRQs. This fixes a source of spurious IRQs
+				when the system masks IRQs.
 		biosirq		[X86-32] Use PCI BIOS calls to get the interrupt
 				routing table. These calls are known to be buggy
 				on several machines and they hang the machine

arch/x86/pci/common.c

@@ -23,6 +23,7 @@ unsigned int pci_probe = PCI_PROBE_BIOS | PCI_PROBE_CONF1 | PCI_PROBE_CONF2 |
 static int pci_bf_sort;
 int pci_routeirq;
 int noioapicquirk;
+int noioapicreroute = 1;
 int pcibios_last_bus = -1;
 unsigned long pirq_table_addr;
 struct pci_bus *pci_root_bus;
@@ -499,6 +500,10 @@ char * __devinit  pcibios_setup(char *str)
 	} else if (!strcmp(str, "noioapicquirk")) {
 		noioapicquirk = 1;
 		return NULL;
+	} else if (!strcmp(str, "ioapicreroute")) {
+		if (noioapicreroute != -1)
+			noioapicreroute = 0;
+		return NULL;
 	}
 	return str;
 }

include/asm-x86/io_apic.h

@@ -160,12 +160,16 @@ extern int skip_ioapic_setup;
 /* 1 if "noapic" boot option passed */
 extern int noioapicquirk;
 
+/* -1 if "noapic" boot option passed */
+extern int noioapicreroute;
+
 /* 1 if the timer IRQ uses the '8259A Virtual Wire' mode */
 extern int timer_through_8259;
 
 static inline void disable_ioapic_setup(void)
 {
 	noioapicquirk = 1;
+	noioapicreroute = -1;
 	skip_ioapic_setup = 1;
 }
 

include/asm-x86/pci.h

@@ -20,6 +20,7 @@ struct pci_sysdata {
 
 extern int pci_routeirq;
 extern int noioapicquirk;
+extern int ioapicreroute;
 
 /* scan a bus after allocating a pci_sysdata for it */
 extern struct pci_bus *pci_scan_bus_on_node(int busno, struct pci_ops *ops,