[tip:x86/apic] x86/apic: Handle XAPIC remap mode proper.

[tip-bot for Jiang Liu]

Commit-ID:  ef1b2b8ad13858ab2f87c05261b8ce3253f90af9
Gitweb:     http://git.kernel.org/tip/ef1b2b8ad13858ab2f87c05261b8ce3253f90af9
Author:     Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
AuthorDate: Wed, 7 Jan 2015 15:31:34 +0800
Committer:  Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Thu, 15 Jan 2015 11:24:23 +0100

x86/apic: Handle XAPIC remap mode proper.

If remapping is in XAPIC mode, the setup code just skips X2APIC
initialization without checking max CPU APIC ID in system, which may
cause problem if system has a CPU with APIC ID bigger than 255.

Handle IR in XAPIC mode the same way as if remapping is disabled.

[ tglx: Split out from previous patch ]

Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Yinghai Lu <yinghai@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: HATAYAMA Daisuke <d.hatayama@xxxxxxxxxxxxxx>
Cc: Jan Beulich <JBeulich@xxxxxxxx>
Cc: Richard Weinberger <richard@xxxxxx>
Cc: Oren Twaig <oren@xxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1420615903-28253-8-git-send-email-jiang.liu@xxxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 arch/x86/kernel/apic/apic.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index fa77be8..04aec6b 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1596,7 +1596,7 @@ static __init void try_to_enable_x2apic(int ir_stat)
 	if (!x2apic_supported())
 		return;
 
-	if (ir_stat < 0) {
+	if (ir_stat != IRQ_REMAP_X2APIC_MODE) {
 		/* IR is required if there is APIC ID > 255 even when running
 		 * under KVM
 		 */
@@ -1613,10 +1613,6 @@ static __init void try_to_enable_x2apic(int ir_stat)
 		 * only in physical mode
 		 */
 		x2apic_force_phys();
-
-	} else if (ir_stat == IRQ_REMAP_XAPIC_MODE) {
-		pr_info("x2apic not enabled, IRQ remapping is in xapic mode\n");
-		return;
 	}
 
 	if (!x2apic_mode) {
--
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