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

From: Dou Liyang
Date: Wed Mar 29 2017 - 10:56:18 EST


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