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, 30 insertions, 1 deletions

diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
index 19381b90e619..db3dcaf4ddf0 100644
--- a/drivers/iommu/irq_remapping.c
+++ b/drivers/iommu/irq_remapping.c
@@ -1,3 +1,4 @@
+#include <linux/cpumask.h>
 #include <linux/kernel.h>
 #include <linux/string.h>
 #include <linux/cpumask.h>
@@ -6,6 +7,9 @@
 
 #include <asm/hw_irq.h>
 #include <asm/irq_remapping.h>
+#include <asm/processor.h>
+#include <asm/x86_init.h>
+#include <asm/apic.h>
 
 #include "irq_remapping.h"
 
@@ -17,6 +21,24 @@ int no_x2apic_optout;
 
 static struct irq_remap_ops *remap_ops;
 
+static void irq_remapping_disable_io_apic(void)
+{
+        /*
+         * 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 (cpu_has_apic || apic_from_smp_config())
+                disconnect_bsp_APIC(0);
+}
+
+static void __init irq_remapping_modify_x86_ops(void)
+{
+        x86_io_apic_ops.disable =       irq_remapping_disable_io_apic;
+}
+
 static __init int setup_nointremap(char *str)
 {
         disable_irq_remap = 1;
@@ -79,10 +101,17 @@ int __init irq_remapping_prepare(void)
 
 int __init irq_remapping_enable(void)
 {
+        int ret;
+
         if (!remap_ops || !remap_ops->enable)
                 return -ENODEV;
 
-        return remap_ops->enable();
+        ret = remap_ops->enable();
+
+        if (irq_remapping_enabled)
+                irq_remapping_modify_x86_ops();
+
+        return ret;
 }
 
 void irq_remapping_disable(void)