From 8d80696060eedf49c080c0f2cf39a20ae7e787f9 Mon Sep 17 00:00:00 2001
From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 15 Jan 2015 21:22:09 +0000
Subject: [PATCH] x86/apic: Avoid open coded x2apic detection
enable_IR_x2apic() grew a open coded x2apic detection. Implement a
proper helper function which shares the code with the already existing
x2apic_enabled().
Made it use rdmsrl_safe as suggested by Boris.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Tony Luck <tony.luck@intel.com>
Link: http://lkml.kernel.org/r/20150115211702.285038186@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/include/asm/apic.h | 19 ++++++++++---------
arch/x86/kernel/apic/apic.c | 5 +----
2 files changed, 11 insertions(+), 13 deletions(-)
diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index 465b309af254..1a8ba26c2fbd 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -108,6 +108,15 @@ extern u64 native_apic_icr_read(void);
extern int x2apic_mode;
+static inline bool apic_is_x2apic_enabled(void)
+{
+ u64 msr;
+
+ if (rdmsrl_safe(MSR_IA32_APICBASE, &msr))
+ return false;
+ return msr & X2APIC_ENABLE;
+}
+
#ifdef CONFIG_X86_X2APIC
/*
* Make previous memory operations globally visible before
@@ -175,15 +184,7 @@ 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)
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 35e6d09294ed..7ecfce13be05 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/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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