[patch 01/23] x86/apic: Avoid open coded x2apic detection

[Thomas Gleixner]

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 <tglx@xxxxxxxxxxxxx>
---
 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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