enable_IR_x2apic() grew a open coded x2apic detection. Implement a
proper helper function which shares the code with the already existing
x2apic_enabled().

Signed-off-by: Thomas Gleixner <t...@linutronix.de>
---
 arch/x86/include/asm/apic.h |   18 +++++++++---------
 arch/x86/kernel/apic/apic.c |    5 +----
 2 files changed, 10 insertions(+), 13 deletions(-)

Index: tip/arch/x86/include/asm/apic.h
===================================================================
--- tip.orig/arch/x86/include/asm/apic.h
+++ tip/arch/x86/include/asm/apic.h
@@ -108,6 +108,14 @@ extern u64 native_apic_icr_read(void);
 
 extern int x2apic_mode;
 
+static inline bool apic_is_x2apic_enabled(void)
+{
+       u64 msr;
+
+       rdmsrl(MSR_IA32_APICBASE, msr);
+       return msr & X2APIC_ENABLE;
+}
+
 #ifdef CONFIG_X86_X2APIC
 /*
  * Make previous memory operations globally visible before
@@ -175,15 +183,7 @@ extern void check_x2apic(void);
 extern void enable_x2apic(void);
 static inline int x2apic_enabled(void)
 {
-       u64 msr;
-
-       if (!cpu_has_x2apic)
-               return 0;
-
-       rdmsrl(MSR_IA32_APICBASE, msr);
-       if (msr & X2APIC_ENABLE)
-               return 1;
-       return 0;
+       return cpu_has_x2apic && apic_is_x2apic_enabled();
 }
 
 #define x2apic_supported()     (cpu_has_x2apic)
Index: tip/arch/x86/kernel/apic/apic.c
===================================================================
--- tip.orig/arch/x86/kernel/apic/apic.c
+++ tip/arch/x86/kernel/apic/apic.c
@@ -1625,10 +1625,7 @@ void __init enable_IR_x2apic(void)
        int ret, ir_stat;
 
        if (!IS_ENABLED(CONFIG_X86_X2APIC)) {
-               u64 msr;
-
-               rdmsrl(MSR_IA32_APICBASE, msr);
-               if (msr & X2APIC_ENABLE)
+               if (apic_is_x2apic_enabled())
                        panic("BIOS has enabled x2apic but kernel doesn't 
support x2apic, please disable x2apic in BIOS.\n");
        }
 


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