[RFC PATCH 5/6] x86/apic: Make the APIC mode setup earlier for UP system

[Dou Liyang]

The SMP-capable system has already enable and setup the APIC mode
as soon as possible.

Do it for UP system and make the code clear.

Signed-off-by: Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>
---
 arch/x86/include/asm/apic.h |  2 ++
 arch/x86/kernel/apic/apic.c | 81 +++++++++++++++++----------------------------
 arch/x86/kernel/smpboot.c   | 58 ++++----------------------------
 3 files changed, 38 insertions(+), 103 deletions(-)

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index be2abc3..fb06fe5 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -55,6 +55,8 @@ extern unsigned int lapic_timer_frequency;
 
 #ifdef CONFIG_SMP
 extern void __inquire_remote_apic(int apicid);
+extern int disable_smp_by_APIC;
+
 #else /* CONFIG_SMP */
 static inline void __inquire_remote_apic(int apicid)
 {
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index ce8f88d..c93c33d 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -169,6 +169,9 @@ __setup("apicpmtimer", setup_apicpmtimer);
 
 unsigned long mp_lapic_addr;
 int disable_apic;
+/* disable smp flag according to APIC configuration */
+int disable_smp_by_APIC;
+
 /* Disable local APIC timer from the kernel commandline or via dmi quirk */
 static int disable_apic_timer __initdata;
 /* Local APIC timer works in C2 */
@@ -1157,13 +1160,13 @@ enum apic_bsp_mode {
 	APIC_BSP_MODEL_PIC = 0,
 	APIC_BSP_MODEL_VIRTUAL_WIRE,
 	APIC_BSP_MODEL_SYMMETRIC_IO,
+	APIC_BSP_MODEL_SYMMETRIC_IO_NO_CONFIG,
 	APIC_BSP_MODEL_SYMMETRIC_IO_NO_ROUTING,
 	APIC_BSP_MODEL_COUNT
 };
 
-static int __init apic_bsp_mode_check(void)
+static int __init apic_bsp_mode_check(int *upmode)
 {
-
 	/* Check kernel option */
 	if (disable_apic) {
 		pr_info("APIC disabled by kernel option\n");
@@ -1200,8 +1203,11 @@ static int __init apic_bsp_mode_check(void)
 		disable_ioapic_support();
 
 		/* Check local APIC, if SMP_NO_CONFIG */
-		if (!acpi_lapic)
-			pr_info("SMP motherboard not detected\n");
+		if (!acpi_lapic) {
+			*upmode = true;
+			pr_info("SMP motherboard not detected.\n");
+			return APIC_BSP_MODEL_SYMMETRIC_IO_NO_CONFIG;
+		}
 
 		return APIC_BSP_MODEL_VIRTUAL_WIRE;
 	}
@@ -1229,7 +1235,13 @@ static int __init apic_bsp_mode_check(void)
 
 	return APIC_BSP_MODEL_SYMMETRIC_IO;
 #else
-	return APIC_BSP_MODEL_PIC;
+#ifdef CONFIG_UP_LATE_INIT
+		/* In UP system, If it supports late init */
+		*upmode = true;
+		return APIC_BSP_MODEL_SYMMETRIC_IO;
+#else
+		return APIC_BSP_MODEL_PIC;
+#endif
 #endif
 }
 
@@ -1285,9 +1297,12 @@ void apic_virture_wire_mode_setup(void)
 /* init the interrupt routing model for the BSP */
 void __init init_bsp_APIC(void)
 {
-	switch (apic_bsp_mode_check()) {
+	int upmode = false;
+
+	switch (apic_bsp_mode_check(&upmode)) {
 	case APIC_BSP_MODEL_PIC:
 		pr_info("Keep in PIC mode(8259)\n");
+		disable_smp_by_APIC = 1;
 		return;
 	case APIC_BSP_MODEL_VIRTUAL_WIRE:
 		pr_info("switch to virtual wire model.\n");
@@ -1295,13 +1310,17 @@ void __init init_bsp_APIC(void)
 	case APIC_BSP_MODEL_SYMMETRIC_IO:
 		pr_info("switch to symmectic I/O model.\n");
 		default_setup_apic_routing();
-		apic_bsp_setup(false);
-		return;
+		break;
+	case APIC_BSP_MODEL_SYMMETRIC_IO_NO_CONFIG:
+		pr_info("switch to symmectic I/O model with no SMP config.\n");
+		disable_smp_by_APIC = 2;
+		default_setup_apic_routing();
+		break;
 	case APIC_BSP_MODEL_SYMMETRIC_IO_NO_ROUTING:
 		pr_info("switch to symmectic I/O model with no apic routing.\n");
-		apic_bsp_setup(false);
-		return;
+		break;
 	}
+	apic_bsp_setup(upmode);
 }
 
 static void lapic_setup_esr(void)
@@ -2392,50 +2411,10 @@ 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);
-	apic_bsp_timer_setup();
-	return 0;
-}
-
 #ifdef CONFIG_UP_LATE_INIT
 void __init up_late_init(void)
 {
-	APIC_init_uniprocessor();
+	apic_bsp_timer_setup();
 }
 #endif
 
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index a556281..b7a810c 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1183,17 +1183,10 @@ static __init void disable_smp(void)
 	cpumask_set_cpu(0, topology_core_cpumask(0));
 }
 
-enum {
-	SMP_OK,
-	SMP_NO_CONFIG,
-	SMP_NO_APIC,
-	SMP_FORCE_UP,
-};
-
 /*
  * Various sanity checks.
  */
-static int __init smp_sanity_check(unsigned max_cpus)
+static void __init smp_sanity_check(void)
 {
 	preempt_disable();
 
@@ -1231,16 +1224,6 @@ static int __init smp_sanity_check(unsigned max_cpus)
 	}
 
 	/*
-	 * If we couldn't find an SMP configuration at boot time,
-	 * get out of here now!
-	 */
-	if (!smp_found_config && !acpi_lapic) {
-		preempt_enable();
-		pr_notice("SMP motherboard not detected\n");
-		return SMP_NO_CONFIG;
-	}
-
-	/*
 	 * Should not be necessary because the MP table should list the boot
 	 * CPU too, but we do it for the sake of robustness anyway.
 	 */
@@ -1251,28 +1234,6 @@ static int __init smp_sanity_check(unsigned max_cpus)
 	}
 	preempt_enable();
 
-	/*
-	 * If we couldn't find a local APIC, then get out of here now!
-	 */
-	if (APIC_INTEGRATED(boot_cpu_apic_version) &&
-	    !boot_cpu_has(X86_FEATURE_APIC)) {
-		if (!disable_apic) {
-			pr_err("BIOS bug, local APIC #%d not detected!...\n",
-				boot_cpu_physical_apicid);
-			pr_err("... forcing use of dummy APIC emulation (tell your hw vendor)\n");
-		}
-		return SMP_NO_APIC;
-	}
-
-	/*
-	 * If SMP should be disabled, then really disable it!
-	 */
-	if (!max_cpus) {
-		pr_info("SMP mode deactivated\n");
-		return SMP_FORCE_UP;
-	}
-
-	return SMP_OK;
 }
 
 static void __init smp_cpu_index_default(void)
@@ -1321,20 +1282,13 @@ void __init native_smp_prepare_cpus(unsigned int max_cpus)
 
 	set_cpu_sibling_map(0);
 
-	switch (smp_sanity_check(max_cpus)) {
-	case SMP_NO_CONFIG:
-		disable_smp();
-		if (APIC_init_uniprocessor())
-			pr_notice("Local APIC not detected. Using dummy APIC emulation.\n");
-		return;
-	case SMP_NO_APIC:
-		disable_smp();
-		return;
-	case SMP_FORCE_UP:
+	smp_sanity_check();
+
+	if (disable_smp_by_APIC) {
+		if (disable_smp_by_APIC == 2)
+			apic_bsp_timer_setup();
 		disable_smp();
 		return;
-	case SMP_OK:
-		break;
 	}
 
 	cpu0_logical_apicid = apic_bsp_timer_setup();
-- 
2.5.5