x86, io_apic: Introduce x86_io_apic_ops.disable()

This function pointer is used to call a system-specific
function for disabling the IO-APIC. Currently this is used
for IRQ remapping which has its own disable routine.

Also introduce the necessary infrastructure in the interrupt
remapping code to overwrite this and other function pointers
as necessary by interrupt remapping.

Signed-off-by: Joerg Roedel <joro@8bytes.org>
Acked-by: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

1 files changed, 19 insertions, 22 deletions

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 2016f9dabd72..cd5f4d7cc163 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1921,30 +1921,14 @@ void __init enable_IO_APIC(void)
 	clear_IO_APIC();
 }
 
-/*
- * Not an __init, needed by the reboot code
- */
-void disable_IO_APIC(void)
+void native_disable_io_apic(void)
 {
 	/*
-	 * Clear the IO-APIC before rebooting:
-	 */
-	clear_IO_APIC();
-
-	if (!legacy_pic->nr_legacy_irqs)
-		return;
-
-	/*
 	 * If the i8259 is routed through an IOAPIC
 	 * Put that IOAPIC in virtual wire mode
 	 * so legacy interrupts can be delivered.
-	 *
-	 * With interrupt-remapping, for now we will use virtual wire A mode,
-	 * as virtual wire B is little complex (need to configure both
-	 * IOAPIC RTE as well as interrupt-remapping table entry).
-	 * As this gets called during crash dump, keep this simple for now.
 	 */
-	if (ioapic_i8259.pin != -1 && !irq_remapping_enabled) {
+	if (ioapic_i8259.pin != -1) {
 		struct IO_APIC_route_entry entry;
 
 		memset(&entry, 0, sizeof(entry));
@@ -1964,12 +1948,25 @@ void disable_IO_APIC(void)
 		ioapic_write_entry(ioapic_i8259.apic, ioapic_i8259.pin, entry);
 	}
 
+	if (cpu_has_apic || apic_from_smp_config())
+		disconnect_bsp_APIC(ioapic_i8259.pin != -1);
+
+}
+
+/*
+ * Not an __init, needed by the reboot code
+ */
+void disable_IO_APIC(void)
+{
 	/*
-	 * Use virtual wire A mode when interrupt remapping is enabled.
+	 * Clear the IO-APIC before rebooting:
 	 */
-	if (cpu_has_apic || apic_from_smp_config())
-		disconnect_bsp_APIC(!irq_remapping_enabled &&
-				ioapic_i8259.pin != -1);
+	clear_IO_APIC();
+
+	if (!legacy_pic->nr_legacy_irqs)
+		return;
+
+	x86_io_apic_ops.disable();
 }
 
 #ifdef CONFIG_X86_32