From: Yinghai Lu <yhlu.kernel@gmail.com>
Subject: x2apic: fix reserved APIC register accesses in print_local_APIC()
References: fate #303948 and fate #303984
Patch-Mainline: queued for .28
Commit-ID: 2c72d93f6593f386f5760ca8e7ac7026948c31d7

Signed-off-by: Thomas Renninger <trenn@suse.de>

APIC_ARBPRI is a reserved register for XAPIC and beyond.
APIC_RRR is a reserved register except for 82489DX, APIC for Pentium processors.
APIC_EOI is a write only register.
APIC_DFR is reserved in x2apic mode.

Access to these registers in x2apic will result in #GP fault. Fix these
apic register accesses.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

---
 arch/x86/kernel/io_apic_32.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

Index: linux-2.6.26/arch/x86/kernel/io_apic_32.c
===================================================================
--- linux-2.6.26.orig/arch/x86/kernel/io_apic_32.c
+++ linux-2.6.26/arch/x86/kernel/io_apic_32.c
@@ -1500,9 +1500,11 @@ void /*__init*/ print_local_APIC(void *d
 	printk(KERN_DEBUG "... APIC TASKPRI: %08x (%02x)\n", v, v & APIC_TPRI_MASK);
 
 	if (APIC_INTEGRATED(ver)) {			/* !82489DX */
-		v = apic_read(APIC_ARBPRI);
-		printk(KERN_DEBUG "... APIC ARBPRI: %08x (%02x)\n", v,
-			v & APIC_ARBPRI_MASK);
+		if (!APIC_XAPIC(ver)) {
+			v = apic_read(APIC_ARBPRI);
+			printk(KERN_DEBUG "... APIC ARBPRI: %08x (%02x)\n", v,
+			       v & APIC_ARBPRI_MASK);
+		}
 		v = apic_read(APIC_PROCPRI);
 		printk(KERN_DEBUG "... APIC PROCPRI: %08x\n", v);
 	}