[tip:x86/apic] x86/x2apic: Add proper state tracking

From: tip-bot for Thomas Gleixner
Date: Thu Jan 22 2015 - 09:27:51 EST


Commit-ID: 12e189d3cfa4c64de758bde18626184bf32c65fc
Gitweb: http://git.kernel.org/tip/12e189d3cfa4c64de758bde18626184bf32c65fc
Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
AuthorDate: Thu, 15 Jan 2015 21:22:22 +0000
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Thu, 22 Jan 2015 15:10:55 +0100

x86/x2apic: Add proper state tracking

Having 3 different variables to track the state is just silly and
error prone. Add a proper state tracking variable which covers the
three possible states: ON/OFF/DISABLED.

We cannot use x2apic_mode for this as this would require to change all
users of x2apic_mode with explicit comparisons for a state value
instead of treating it as boolean.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Acked-by: Borislav Petkov <bp@xxxxxxxxx>
Cc: Jiang Liu <jiang.liu@xxxxxxxxxxxxxxx>
Cc: Joerg Roedel <joro@xxxxxxxxxx>
Cc: Tony Luck <tony.luck@xxxxxxxxx>
Link: http://lkml.kernel.org/r/20150115211702.955392443@xxxxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
arch/x86/kernel/apic/apic.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 06b7521..b374b0d 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1480,6 +1480,14 @@ static bool nox2apic __initdata;
#ifdef CONFIG_X86_X2APIC
int x2apic_mode;
static int x2apic_disabled;
+
+enum {
+ X2APIC_OFF,
+ X2APIC_ON,
+ X2APIC_DISABLED,
+};
+static int x2apic_state;
+
static int __init setup_nox2apic(char *str)
{
if (x2apic_enabled()) {
@@ -1496,7 +1504,7 @@ static int __init setup_nox2apic(char *str)
setup_clear_cpu_cap(X86_FEATURE_X2APIC);

nox2apic = true;
-
+ x2apic_state = X2APIC_DISABLED;
return 0;
}
early_param("nox2apic", setup_nox2apic);
@@ -1539,6 +1547,7 @@ static __init void disable_x2apic(void)
}

x2apic_disabled = 1;
+ x2apic_state = X2APIC_DISABLED;
}

void enable_x2apic(void)
@@ -1559,6 +1568,7 @@ void enable_x2apic(void)
printk_once(KERN_INFO "Enabling x2apic\n");
wrmsrl(MSR_IA32_APICBASE, msr | X2APIC_ENABLE);
}
+ x2apic_state = X2APIC_ON;
}

static __init void try_to_enable_x2apic(int remap_mode)
@@ -1597,6 +1607,9 @@ void __init check_x2apic(void)
if (x2apic_enabled()) {
pr_info("x2apic: enabled by BIOS, switching to x2apic ops\n");
x2apic_mode = 1;
+ x2apic_state = X2APIC_ON;
+ } else if (!cpu_has_x2apic) {
+ x2apic_state = X2APIC_DISABLED;
}
}
#else /* CONFIG_X86_X2APIC */
--
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