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x86/apic: Refine enable_IR_x2apic() and related functions

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Refine enable_IR_x2apic() and related functions for better readability.

[ tglx: Removed the XAPIC mode change and split it out into a seperate
  	patch. Added comments. ]

Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: iommu@lists.linux-foundation.org
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David Rientjes <rientjes@google.com>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Jan Beulich <JBeulich@suse.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Oren Twaig <oren@scalemp.com>
Link: http://lkml.kernel.org/r/1420615903-28253-8-git-send-email-jiang.liu@linux.intel.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Jiang Liu 2015-01-07 15:31:34 +08:00 committed by Thomas Gleixner
parent 89356cf20e
commit 07806c50bd
1 changed files with 48 additions and 46 deletions
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94
arch/x86/kernel/apic/apic.c
View File

@ -1573,7 +1573,7 @@ void enable_x2apic(void)
}
#endif /* CONFIG_X86_X2APIC */
int __init enable_IR(void)
static int __init try_to_enable_IR(void)
{
#ifdef CONFIG_IRQ_REMAP
if (!irq_remapping_supported()) {
@ -1586,17 +1586,51 @@ int __init enable_IR(void)
"io-apic setup\n");
return -1;
}
return irq_remapping_enable();
#endif
return -1;
return irq_remapping_enable();
}
static __init void try_to_enable_x2apic(int ir_stat)
{
#ifdef CONFIG_X86_X2APIC
if (!x2apic_supported())
return;
if (ir_stat < 0) {
/* IR is required if there is APIC ID > 255 even when running
* under KVM
*/
if (max_physical_apicid > 255 ||
!hypervisor_x2apic_available()) {
pr_info("IRQ remapping doesn't support X2APIC mode, disable x2apic.\n");
if (x2apic_preenabled)
disable_x2apic();
return;
}
/*
* without IR all CPUs can be addressed by IOAPIC/MSI
* 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) {
x2apic_mode = 1;
enable_x2apic();
pr_info("Enabled x2apic\n");
}
#endif
}
void __init enable_IR_x2apic(void)
{
unsigned long flags;
int ret;
int hardware_init_ret;
int ret, ir_stat;
if (!IS_ENABLED(CONFIG_X86_X2APIC)) {
u64 msr;
@ -1606,8 +1640,8 @@ void __init enable_IR_x2apic(void)
panic("BIOS has enabled x2apic but kernel doesn't support x2apic, please disable x2apic in BIOS.\n");
}
hardware_init_ret = irq_remapping_prepare();
if (hardware_init_ret && !x2apic_supported())
ir_stat = irq_remapping_prepare();
if (ir_stat < 0 && !x2apic_supported())
return;
ret = save_ioapic_entries();
@ -1622,45 +1656,13 @@ void __init enable_IR_x2apic(void)
if (x2apic_preenabled && nox2apic)
disable_x2apic();
/* If irq_remapping_prepare() succeded, try to enable it */
if (ir_stat >= 0)
ir_stat = try_to_enable_IR();
/* ir_stat contains the remap mode or an error code */
try_to_enable_x2apic(ir_stat);
if (hardware_init_ret)
ret = -1;
else
ret = enable_IR();
if (!x2apic_supported())
goto skip_x2apic;
if (ret < 0) {
/* IR is required if there is APIC ID > 255 even when running
* under KVM
*/
if (max_physical_apicid > 255 ||
!hypervisor_x2apic_available()) {
if (x2apic_preenabled)
disable_x2apic();
goto skip_x2apic;
}
/*
* without IR all CPUs can be addressed by IOAPIC/MSI
* only in physical mode
*/
x2apic_force_phys();
}
if (ret == IRQ_REMAP_XAPIC_MODE) {
pr_info("x2apic not enabled, IRQ remapping is in xapic mode\n");
goto skip_x2apic;
}
if (x2apic_supported() && !x2apic_mode) {
x2apic_mode = 1;
enable_x2apic();
pr_info("Enabled x2apic\n");
}
skip_x2apic:
if (ret < 0) /* IR enabling failed */
if (ir_stat < 0)
restore_ioapic_entries();
legacy_pic->restore_mask();
local_irq_restore(flags);