4.4-stable patches

added patches:
	x86-timer-skip-pit-initialization-on-modern-chipsets.patch

diff --git a/queue-4.4/series b/queue-4.4/series
index 5d7764d36eb40a1d8765b2b5a6997a376e3e43b8..07efd9ea72415867546a97938327128af92e0b17 100644 (file)
--- a/queue-4.4/series
+++ b/queue-4.4/series
@@ -97,3 +97,4 @@ fuse-use-read_once-on-congestion_threshold-and-max_b.patch
 bluetooth-hci_ldisc-fix-null-pointer-derefence-in-case-of-early-data.patch
 bluetooth-hci_ldisc-postpone-hci_uart_proto_ready-bit-set-in-hci_uart_set_proto.patch
 memfd-use-radix_tree_deref_slot_protected-to-avoid-the-warning.patch
+x86-timer-skip-pit-initialization-on-modern-chipsets.patch

diff --git a/queue-4.4/x86-timer-skip-pit-initialization-on-modern-chipsets.patch b/queue-4.4/x86-timer-skip-pit-initialization-on-modern-chipsets.patch
new file mode 100644 (file)
index 0000000..debe194
--- /dev/null
+++ b/queue-4.4/x86-timer-skip-pit-initialization-on-modern-chipsets.patch
@@ -0,0 +1,209 @@
+From c8c4076723daca08bf35ccd68f22ea1c6219e207 Mon Sep 17 00:00:00 2001
+From: Thomas Gleixner <tglx@linutronix.de>
+Date: Fri, 28 Jun 2019 15:23:07 +0800
+Subject: x86/timer: Skip PIT initialization on modern chipsets
+
+From: Thomas Gleixner <tglx@linutronix.de>
+
+commit c8c4076723daca08bf35ccd68f22ea1c6219e207 upstream.
+
+Recent Intel chipsets including Skylake and ApolloLake have a special
+ITSSPRC register which allows the 8254 PIT to be gated.  When gated, the
+8254 registers can still be programmed as normal, but there are no IRQ0
+timer interrupts.
+
+Some products such as the Connex L1430 and exone go Rugged E11 use this
+register to ship with the PIT gated by default. This causes Linux to fail
+to boot:
+
+  Kernel panic - not syncing: IO-APIC + timer doesn't work! Boot with
+  apic=debug and send a report.
+
+The panic happens before the framebuffer is initialized, so to the user, it
+appears as an early boot hang on a black screen.
+
+Affected products typically have a BIOS option that can be used to enable
+the 8254 and make Linux work (Chipset -> South Cluster Configuration ->
+Miscellaneous Configuration -> 8254 Clock Gating), however it would be best
+to make Linux support the no-8254 case.
+
+Modern sytems allow to discover the TSC and local APIC timer frequencies,
+so the calibration against the PIT is not required. These systems have
+always running timers and the local APIC timer works also in deep power
+states.
+
+So the setup of the PIT including the IO-APIC timer interrupt delivery
+checks are a pointless exercise.
+
+Skip the PIT setup and the IO-APIC timer interrupt checks on these systems,
+which avoids the panic caused by non ticking PITs and also speeds up the
+boot process.
+
+Thanks to Daniel for providing the changelog, initial analysis of the
+problem and testing against a variety of machines.
+
+Reported-by: Daniel Drake <drake@endlessm.com>
+Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
+Tested-by: Daniel Drake <drake@endlessm.com>
+Cc: bp@alien8.de
+Cc: hpa@zytor.com
+Cc: linux@endlessm.com
+Cc: rafael.j.wysocki@intel.com
+Cc: hdegoede@redhat.com
+Link: https://lkml.kernel.org/r/20190628072307.24678-1-drake@endlessm.com
+Cc: Kai-Heng Feng <kai.heng.feng@canonical.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ arch/x86/include/asm/apic.h    |    2 ++
+ arch/x86/include/asm/time.h    |    1 +
+ arch/x86/kernel/apic/apic.c    |   27 +++++++++++++++++++++++++++
+ arch/x86/kernel/apic/io_apic.c |    4 ++++
+ arch/x86/kernel/i8253.c        |   25 ++++++++++++++++++++++++-
+ arch/x86/kernel/time.c         |    7 +++++--
+ 6 files changed, 63 insertions(+), 3 deletions(-)
+
+--- a/arch/x86/include/asm/apic.h
++++ b/arch/x86/include/asm/apic.h
+@@ -157,6 +157,7 @@ static inline int apic_is_clustered_box(
+ #endif
+ 
+ extern int setup_APIC_eilvt(u8 lvt_off, u8 vector, u8 msg_type, u8 mask);
++extern bool apic_needs_pit(void);
+ 
+ #else /* !CONFIG_X86_LOCAL_APIC */
+ static inline void lapic_shutdown(void) { }
+@@ -165,6 +166,7 @@ static inline void init_apic_mappings(vo
+ static inline void disable_local_APIC(void) { }
+ # define setup_boot_APIC_clock x86_init_noop
+ # define setup_secondary_APIC_clock x86_init_noop
++static inline bool apic_needs_pit(void) { return true; }
+ #endif /* !CONFIG_X86_LOCAL_APIC */
+ 
+ #ifdef CONFIG_X86_X2APIC
+--- a/arch/x86/include/asm/time.h
++++ b/arch/x86/include/asm/time.h
+@@ -6,6 +6,7 @@
+ 
+ extern void hpet_time_init(void);
+ extern void time_init(void);
++extern bool pit_timer_init(void);
+ 
+ extern struct clock_event_device *global_clock_event;
+ 
+--- a/arch/x86/kernel/apic/apic.c
++++ b/arch/x86/kernel/apic/apic.c
+@@ -674,6 +674,33 @@ calibrate_by_pmtimer(long deltapm, long
+       return 0;
+ }
+ 
++bool __init apic_needs_pit(void)
++{
++      /*
++       * If the frequencies are not known, PIT is required for both TSC
++       * and apic timer calibration.
++       */
++      if (!tsc_khz || !cpu_khz)
++              return true;
++
++      /* Is there an APIC at all? */
++      if (!boot_cpu_has(X86_FEATURE_APIC))
++              return true;
++
++      /* Deadline timer is based on TSC so no further PIT action required */
++      if (boot_cpu_has(X86_FEATURE_TSC_DEADLINE_TIMER))
++              return false;
++
++      /* APIC timer disabled? */
++      if (disable_apic_timer)
++              return true;
++      /*
++       * The APIC timer frequency is known already, no PIT calibration
++       * required. If unknown, let the PIT be initialized.
++       */
++      return lapic_timer_period == 0;
++}
++
+ static int __init calibrate_APIC_clock(void)
+ {
+       struct clock_event_device *levt = this_cpu_ptr(&lapic_events);
+--- a/arch/x86/kernel/apic/io_apic.c
++++ b/arch/x86/kernel/apic/io_apic.c
+@@ -57,6 +57,7 @@
+ #include <asm/acpi.h>
+ #include <asm/dma.h>
+ #include <asm/timer.h>
++#include <asm/time.h>
+ #include <asm/i8259.h>
+ #include <asm/setup.h>
+ #include <asm/irq_remapping.h>
+@@ -2057,6 +2058,9 @@ static inline void __init check_timer(vo
+       unsigned long flags;
+       int no_pin1 = 0;
+ 
++      if (!global_clock_event)
++              return;
++
+       local_irq_save(flags);
+ 
+       /*
+--- a/arch/x86/kernel/i8253.c
++++ b/arch/x86/kernel/i8253.c
+@@ -7,6 +7,7 @@
+ #include <linux/timex.h>
+ #include <linux/i8253.h>
+ 
++#include <asm/apic.h>
+ #include <asm/hpet.h>
+ #include <asm/time.h>
+ #include <asm/smp.h>
+@@ -17,10 +18,32 @@
+  */
+ struct clock_event_device *global_clock_event;
+ 
+-void __init setup_pit_timer(void)
++/*
++ * Modern chipsets can disable the PIT clock which makes it unusable. It
++ * would be possible to enable the clock but the registers are chipset
++ * specific and not discoverable. Avoid the whack a mole game.
++ *
++ * These platforms have discoverable TSC/CPU frequencies but this also
++ * requires to know the local APIC timer frequency as it normally is
++ * calibrated against the PIT interrupt.
++ */
++static bool __init use_pit(void)
+ {
++      if (!IS_ENABLED(CONFIG_X86_TSC) || !boot_cpu_has(X86_FEATURE_TSC))
++              return true;
++
++      /* This also returns true when APIC is disabled */
++      return apic_needs_pit();
++}
++
++bool __init pit_timer_init(void)
++{
++      if (!use_pit())
++              return false;
++
+       clockevent_i8253_init(true);
+       global_clock_event = &i8253_clockevent;
++      return true;
+ }
+ 
+ #ifndef CONFIG_X86_64
+--- a/arch/x86/kernel/time.c
++++ b/arch/x86/kernel/time.c
+@@ -76,8 +76,11 @@ void __init setup_default_timer_irq(void
+ /* Default timer init function */
+ void __init hpet_time_init(void)
+ {
+-      if (!hpet_enable())
+-              setup_pit_timer();
++      if (!hpet_enable()) {
++              if (!pit_timer_init())
++                      return;
++      }
++
+       setup_default_timer_irq();
+ }
+