Commit-ID: 5fcee53ce705d49c766f8a302c7e93bdfc33c124
Gitweb: http://git.kernel.org/tip/5fcee53ce705d49c766f8a302c7e93bdfc33c124
Author: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
AuthorDate: Wed, 7 Jan 2015 15:31:38 +0800
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Thu, 15 Jan 2015 11:24:23 +0100
x86/apic: Only disable CPU x2apic mode when necessary
When interrupt remapping hardware is not in X2APIC, CPU X2APIC mode
will be disabled if:
1) Maximum CPU APIC ID is bigger than 255
2) hypervisior doesn't support x2apic mode.
But we should only check whether hypervisor supports X2APIC mode when
hypervisor(CONFIG_HYPERVISOR_GUEST) is enabled, otherwise X2APIC will
always be disabled when CONFIG_HYPERVISOR_GUEST is disabled and IR
doesn't work in X2APIC mode.
Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
Tested-by: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Cc: iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx>
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/1420615903-28253-12-git-send-email-jiang.liu@xxxxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/kernel/apic/apic.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 04aec6b..2f16116 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1601,7 +1601,8 @@ static __init void try_to_enable_x2apic(int ir_stat)
* under KVM
*/
if (max_physical_apicid > 255 ||
- !hypervisor_x2apic_available()) {
+ (IS_ENABLED(CONFIG_HYPERVISOR_GUEST) &&
+ !hypervisor_x2apic_available())) {
pr_info("IRQ remapping doesn't support X2APIC mode, disable x2apic.\n");
if (x2apic_preenabled)
disable_x2apic();
--
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