linux-kernel - Re: lapic-related boot crash in 4.15-rc1

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Date:   Thu, 11 Jan 2018 11:10:03 +0800
From:   Dou Liyang <douly.fnst@...fujitsu.com>
To:     Thomas Gleixner <tglx@...utronix.de>, Meelis Roos <mroos@...ux.ee>
CC:     Ingo Molnar <mingo@...nel.org>,
        Linux Kernel list <linux-kernel@...r.kernel.org>,
        <x86@...nel.org>, Ville Syrjala <ville.syrjala@...ux.intel.com>
Subject: Re: lapic-related boot crash in 4.15-rc1

Hi Thomas, Meelis

At 01/11/2018 02:34 AM, Thomas Gleixner wrote:
> On Wed, 10 Jan 2018, Meelis Roos wrote:
>> On 3 of my test computers, boot hangs with 4.15 git kernels. So far I
>> have traced it down to 4.14.0 being good and 4.15-rc1 being bad (bisect
>> is slow because the computers are somwehat remote). Also because of
>> trying to find when it started, I have not tries newer than rc5
>> kernels.
>>
>> The hang happens after Performance Events feature table has been printed
>> but before APIC initialization messages normally appear ("Enabling APIC
>> mode:  Flat.  Using 0 I/O APICs" or something like that).
>>
>> It happens on at least 3 distinct computers:
>> * AMD Athlon with AMD 750 chipset
>> * P3 1 GHz with i815 chipset
>> * P4 1.7 GHz with SiS chipset
>>
>> They all have have "lapic" parameter because they were telling me that
>> lapic has been disabled by BIOS and I re-enabled it with the parameter
>> to get apic timer interrupts. This worked up until 4.14.
>>
>> None of the computers have IO-APICs.
> 
> Oh. Then it possibly falls into Dou's realm.
> 
> Dou?
> 

Ah, This problem looks like what Ville reported[1].

Revert the commit b371ae0d4a19 ("x86/apic: Remove init_bsp_APIC()") may
make it work again.

But, I don't know the true reason.

In Linux v4.15-rc1+, apic->setup_apic_routing() has been called earlier,
So, I guess kernel may hang in some early initcall fuctions. we can add
"initcall_debug" option in the kernel command line for tracing initcalls
as they are executed.

[1] https://marc.info/?l=linux-kernel&m=151188084018443&w=2

Thanks,
	dou.
--------------------------->8-----------------------------------

From: Ville Syrjälä <ville.syrjala@...ux.intel.com>

This reverts commit b371ae0d4a194b178817b0edfb6a7395c7aec37a.

Causes my P3 UP machine to hang at boot with "lapic".

Cc: Dou Liyang <douly.fnst@...fujitsu.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: yinghai@...nel.org
Cc: bhe@...hat.com
Cc: Ingo Molnar <mingo@...hat.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@...ux.intel.com>
---
  arch/x86/include/asm/apic.h |  1 +
  arch/x86/kernel/apic/apic.c | 49 
+++++++++++++++++++++++++++++++++++++++++++++
  arch/x86/kernel/irqinit.c   |  3 +++
  3 files changed, 53 insertions(+)

diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h
index a9e57f08bfa6..98722773391d 100644
--- a/arch/x86/include/asm/apic.h
+++ b/arch/x86/include/asm/apic.h
@@ -136,6 +136,7 @@ extern void disconnect_bsp_APIC(int virt_wire_setup);
  extern void disable_local_APIC(void);
  extern void lapic_shutdown(void);
  extern void sync_Arb_IDs(void);
+extern void init_bsp_APIC(void);
  extern void apic_intr_mode_init(void);
  extern void setup_local_APIC(void);
  extern void init_apic_mappings(void);
diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
index 6e272f3ea984..cec9aaea7f9d 100644
--- a/arch/x86/kernel/apic/apic.c
+++ b/arch/x86/kernel/apic/apic.c
@@ -1286,6 +1286,55 @@ static int __init apic_intr_mode_select(void)
  	return APIC_SYMMETRIC_IO;
  }

+/*
+ * An initial setup of the virtual wire mode.
+ */
+void __init init_bsp_APIC(void)
+{
+	unsigned int value;
+
+	/*
+	 * Don't do the setup now if we have a SMP BIOS as the
+	 * through-I/O-APIC virtual wire mode might be active.
+	 */
+	if (smp_found_config || !boot_cpu_has(X86_FEATURE_APIC))
+		return;
+
+	/*
+	 * Do not trust the local APIC being empty at bootup.
+	 */
+	clear_local_APIC();
+
+	/*
+	 * Enable APIC.
+	 */
+	value = apic_read(APIC_SPIV);
+	value &= ~APIC_VECTOR_MASK;
+	value |= APIC_SPIV_APIC_ENABLED;
+
+#ifdef CONFIG_X86_32
+	/* This bit is reserved on P4/Xeon and should be cleared */
+	if ((boot_cpu_data.x86_vendor == X86_VENDOR_INTEL) &&
+	    (boot_cpu_data.x86 == 15))
+		value &= ~APIC_SPIV_FOCUS_DISABLED;
+	else
+#endif
+		value |= APIC_SPIV_FOCUS_DISABLED;
+	value |= SPURIOUS_APIC_VECTOR;
+	apic_write(APIC_SPIV, value);
+
+	/*
+	 * Set up the virtual wire mode.
+	 */
+	apic_write(APIC_LVT0, APIC_DM_EXTINT);
+	value = APIC_DM_NMI;
+	if (!lapic_is_integrated())		/* 82489DX */
+		value |= APIC_LVT_LEVEL_TRIGGER;
+	if (apic_extnmi == APIC_EXTNMI_NONE)
+		value |= APIC_LVT_MASKED;
+	apic_write(APIC_LVT1, value);
+}
+
  /* Init the interrupt delivery mode for the BSP */
  void __init apic_intr_mode_init(void)
  {
diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
index 8da3e909e967..a539410c4ea9 100644
--- a/arch/x86/kernel/irqinit.c
+++ b/arch/x86/kernel/irqinit.c
@@ -61,6 +61,9 @@ void __init init_ISA_irqs(void)
  	struct irq_chip *chip = legacy_pic->chip;
  	int i;

+#if defined(CONFIG_X86_64) || defined(CONFIG_X86_LOCAL_APIC)
+	init_bsp_APIC();
+#endif
  	legacy_pic->init(0);

  	for (i = 0; i < nr_legacy_irqs(); i++)
-- 
> Thanks,
> 
> 	tglx
> 
> 
>