linux-kernel - [RFC PATCH v2 10/12] x86/apic: Make the interrupt mode setup earlier for UP system

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Date:   Wed, 19 Apr 2017 17:05:24 +0800
From:   Dou Liyang <douly.fnst@...fujitsu.com>
To:     <x86@...nel.org>, <linux-kernel@...r.kernel.org>
CC:     <tglx@...utronix.de>, <mingo@...nel.org>, <hpa@...or.com>,
        <ebiederm@...ssion.com>, <bhe@...hat.com>,
        <izumi.taku@...fujitsu.com>, Dou Liyang <douly.fnst@...fujitsu.com>
Subject: [RFC PATCH v2 10/12] x86/apic: Make the interrupt mode setup earlier for UP system

In UniProcessor kernel with UP_LATE_INIT=y, enable and setup the
interrupt delivery mode in smp_init() which almost be called at the
end of start_kernel().

But, calibrate delay needs the timer interrupt which may be disabled
in dump-capture kernel.

Due to the MP table or ACPI has been read earlier, setup the interrupt
mode as soon as possible to cleanup the disabled situation for UP
kernel and remove the original setup code.

Signed-off-by: Dou Liyang <douly.fnst@...fujitsu.com>
---
 arch/x86/kernel/apic/apic.c | 49 ++++++---------------------------------------
 1 file changed, 6 insertions(+), 43 deletions(-)

diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index a915f09..5d27a24 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1224,9 +1224,12 @@ static int __init apic_bsp_mode_check(int *upmode)
 		pr_info("SMP mode deactivated\n");
 		return APIC_SYMMETRIC_IO_NO_ROUTING;
 	}
+#else
+	/* UP_LATE_INIT is true */
+	*upmode = true;
 #endif
-
 	return APIC_SYMMETRIC_IO;
+
 }
 
 /*
@@ -2375,51 +2378,11 @@ void __init apic_bsp_setup(bool upmode)
 	setup_IO_APIC();
 }
 
-/*
- * This initializes the IO-APIC and APIC hardware if this is
- * a UP kernel.
- */
-int __init APIC_init_uniprocessor(void)
-{
-	if (disable_apic) {
-		pr_info("Apic disabled\n");
-		return -1;
-	}
-#ifdef CONFIG_X86_64
-	if (!boot_cpu_has(X86_FEATURE_APIC)) {
-		disable_apic = 1;
-		pr_info("Apic disabled by BIOS\n");
-		return -1;
-	}
-#else
-	if (!smp_found_config && !boot_cpu_has(X86_FEATURE_APIC))
-		return -1;
-
-	/*
-	 * Complain if the BIOS pretends there is one.
-	 */
-	if (!boot_cpu_has(X86_FEATURE_APIC) &&
-	    APIC_INTEGRATED(boot_cpu_apic_version)) {
-		pr_err("BIOS bug, local APIC 0x%x not detected!...\n",
-			boot_cpu_physical_apicid);
-		return -1;
-	}
-#endif
-
-	if (!smp_found_config)
-		disable_ioapic_support();
-
-	default_setup_apic_routing();
-	apic_bsp_setup(true);
-	/* Setup local timer */
-	x86_init.timers.setup_percpu_clockev();
-	return 0;
-}
-
 #ifdef CONFIG_UP_LATE_INIT
 void __init up_late_init(void)
 {
-	APIC_init_uniprocessor();
+	/* Setup local APIC timer */
+	x86_init.timers.setup_percpu_clockev();
 }
 #endif
 
-- 
2.5.5