x2APIC: improve enabling logic

This patch masks PIC and IOAPIC RTE's before x2APIC enabling, unmask
and restore them after x2APIC enabling. It also really enables
interrupt remapping before x2APIC enabling instead of just checking
interrupt remapping setting. This patch also handles all x2APIC
configuration including BIOS settings and command line
settings. Especially, it handles that BIOS hands over in x2APIC mode
(when there is apic id > 255). It checks if x2APIC is already enabled
by BIOS. If already enabled, it will disable interrupt remapping and
queued invalidation first, then enable them again.

Signed-off-by: Weidong Han <weidong.han@intel.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/xen/arch/x86/i8259.c b/xen/arch/x86/i8259.c
index 2474f7864d..bd9c956ef2 100644
--- a/xen/arch/x86/i8259.c
+++ b/xen/arch/x86/i8259.c
@@ -175,6 +175,26 @@ int i8259A_irq_pending(unsigned int irq)
     return ret;
 }
 
+void mask_8259A(void)
+{
+    unsigned long flags;
+
+    spin_lock_irqsave(&i8259A_lock, flags);
+    outb(0xff, 0xA1);
+    outb(0xff, 0x21);
+    spin_unlock_irqrestore(&i8259A_lock, flags);
+}
+
+void unmask_8259A(void)
+{
+    unsigned long flags;
+
+    spin_lock_irqsave(&i8259A_lock, flags);
+    outb(cached_A1, 0xA1);
+    outb(cached_21, 0x21);
+    spin_unlock_irqrestore(&i8259A_lock, flags);
+}
+
 /*
  * This function assumes to be called rarely. Switching between
  * 8259A registers is slow.