enable_x2apic() is a convoluted unreadable mess because it is used for
both enablement in early boot and for setup in cpu_init().
Split the code into x2apic_enable() for enablement and x2apic_setup()
for setup of (secondary cpus). Make use of the new state tracking to
simplify the logic.
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
---
arch/x86/include/asm/apic.h | 4 +--
arch/x86/kernel/apic/apic.c | 55 +++++++++++++++++++++++++------------------
arch/x86/kernel/cpu/common.c | 2 -
3 files changed, 36 insertions(+), 25 deletions(-)
Index: tip/arch/x86/include/asm/apic.h
===================================================================
--- tip.orig/arch/x86/include/asm/apic.h
+++ tip/arch/x86/include/asm/apic.h
@@ -177,7 +177,7 @@ static inline u64 native_x2apic_icr_read
extern int x2apic_mode;
extern int x2apic_phys;
-extern void enable_x2apic(void);
+extern void x2apic_setup(void);
static inline int x2apic_enabled(void)
{
return cpu_has_x2apic && apic_is_x2apic_enabled();
@@ -185,7 +185,7 @@ static inline int x2apic_enabled(void)
#define x2apic_supported() (cpu_has_x2apic)
#else
-static inline void enable_x2apic(void) { }
+static inline void x2apic_setup(void) { }
static inline int x2apic_enabled(void) { return 0; }
#define x2apic_mode (0)
Index: tip/arch/x86/kernel/apic/apic.c
===================================================================
--- tip.orig/arch/x86/kernel/apic/apic.c
+++ tip/arch/x86/kernel/apic/apic.c
@@ -1497,6 +1497,17 @@ static inline void disable_x2apic(void)
printk_once(KERN_INFO "x2apic disabled\n");
}
+static inline void enable_x2apic(void)
+{
+ u64 msr;
+
+ rdmsrl(MSR_IA32_APICBASE, msr);
+ if (msr & X2APIC_ENABLE)
+ return;
+ wrmsrl(MSR_IA32_APICBASE, msr | X2APIC_ENABLE);
+ printk_once(KERN_INFO "x2apic enabled\n");
+}
+
static int __init setup_nox2apic(char *str)
{
if (x2apic_enabled()) {
@@ -1517,6 +1528,21 @@ static int __init setup_nox2apic(char *s
}
early_param("nox2apic", setup_nox2apic);
+/* Called from cpu_init() to enable x2apic on (secondary) cpus */
+void x2apic_setup(void)
+{
+ /*
+ * If x2apic is not in ON state, disable it if already enabled
+ * from BIOS.
+ */
+ if (x2apic_state != X2APIC_ON) {
+ if (cpu_has_apic)
+ disable_x2apic();
+ return;
+ }
+ enable_x2apic();
+}
+
static __init void x2apic_disable(void)
{
u64 msr;
@@ -1541,30 +1567,19 @@ static __init void x2apic_disable(void)
x2apic_state = X2APIC_DISABLED;
}
-void enable_x2apic(void)
+static __init void x2apic_enable(void)
{
- u64 msr;
-
- if (x2apic_state == X2APIC_DISABLED) {
- disable_x2apic();
- x2apic_mode = 0;
+ if (x2apic_state != X2APIC_OFF)
return;
- }
- if (!x2apic_mode)
- return;
-
- rdmsrl(MSR_IA32_APICBASE, msr);
- if (!(msr & X2APIC_ENABLE)) {
- printk_once(KERN_INFO "Enabling x2apic\n");
- wrmsrl(MSR_IA32_APICBASE, msr | X2APIC_ENABLE);
- }
+ x2apic_mode = 1;
x2apic_state = X2APIC_ON;
+ enable_x2apic();
}
static __init void try_to_enable_x2apic(int remap_mode)
{
- if (!x2apic_supported())
+ if (x2apic_state == X2APIC_DISABLED)
return;
if (remap_mode != IRQ_REMAP_X2APIC_MODE) {
@@ -1585,12 +1600,7 @@ static __init void try_to_enable_x2apic(
*/
x2apic_phys = 1;
}
-
- if (!x2apic_mode) {
- x2apic_mode = 1;
- enable_x2apic();
- pr_info("Enabled x2apic\n");
- }
+ x2apic_enable();
}
void __init check_x2apic(void)
@@ -1614,6 +1624,7 @@ void __init check_x2apic(void)
panic("BIOS has enabled x2apic but kernel doesn't support x2apic,
please disable x2apic in BIOS.\n");
}
static inline void try_to_enable_x2apic(int remap_mode) { }
+static inline void enable_x2apic(void) { }
#endif /* !CONFIG_X86_X2APIC */
static int __init try_to_enable_IR(void)
Index: tip/arch/x86/kernel/cpu/common.c
===================================================================
--- tip.orig/arch/x86/kernel/cpu/common.c
+++ tip/arch/x86/kernel/cpu/common.c
@@ -1332,7 +1332,7 @@ void cpu_init(void)
barrier();
x86_configure_nx();
- enable_x2apic();
+ x2apic_setup();
/*
* set up and load the per-CPU TSS
--
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