From d2d9c4a3d01c20f936f88e0c2793945e6632dab6 Mon Sep 17 00:00:00 2001 From: Sebastian Andrzej Siewior Date: Fri, 21 Oct 2016 10:44:49 +0200 Subject: x86/apic: Get rid of "warning: 'acpi_ioapic_lock' defined but not used" kbuild test robot reported this against the -RT tree: |>> arch/x86/kernel/acpi/boot.c:90:21: warning: 'acpi_ioapic_lock' defined but not used [-Wunused-variable] | static DEFINE_MUTEX(acpi_ioapic_lock); | ^ | include/linux/mutex_rt.h:27:15: note: in definition of macro 'DEFINE_MUTEX' | struct mutex mutexname = __MUTEX_INITIALIZER(mutexname) ^~~~~~~~~ which is also true (as in non-used) for !RT but the compiler does not emit a warning. Reported-by: kbuild test robot Signed-off-by: Sebastian Andrzej Siewior Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20161021084449.32523-1-bigeasy@linutronix.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/acpi/boot.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86/kernel') diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c index 8a5abaa7d453..066ceb7767b8 100644 --- a/arch/x86/kernel/acpi/boot.c +++ b/arch/x86/kernel/acpi/boot.c @@ -76,6 +76,7 @@ int acpi_fix_pin2_polarity __initdata; static u64 acpi_lapic_addr __initdata = APIC_DEFAULT_PHYS_BASE; #endif +#ifdef CONFIG_X86_IO_APIC /* * Locks related to IOAPIC hotplug * Hotplug side: @@ -88,6 +89,7 @@ static u64 acpi_lapic_addr __initdata = APIC_DEFAULT_PHYS_BASE; * ->ioapic_lock */ static DEFINE_MUTEX(acpi_ioapic_lock); +#endif /* -------------------------------------------------------------------------- Boot-time Configuration -- cgit v1.2.3 From 8ca225520e278e41396dab0524989f4848626f83 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Mon, 7 Nov 2016 11:13:40 +0800 Subject: x86/apic: Prevent tracing on apic_msr_write_eoi() The following RCU lockdep warning led to adding irq_enter()/irq_exit() into smp_reschedule_interrupt(): RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks = 0 RCU used illegally from extended quiescent state! no locks held by swapper/1/0. do_trace_write_msr native_write_msr native_apic_msr_eoi_write smp_reschedule_interrupt reschedule_interrupt As Peterz pointed out: | So now we're making a very frequent interrupt slower because of debug | code. | | The thing is, many many smp_reschedule_interrupt() invocations don't | actually execute anything much at all and are only sent to tickle the | return to user path (which does the actual preemption). | | Having to do the whole irq_enter/irq_exit dance just for this unlikely | debug case totally blows. Use the wrmsr_notrace() variant in native_apic_msr_write_eoi, annotate the kvm variant with notrace and add a native_apic_eoi callback to the apic structure so KVM guests are covered as well. This allows to revert the irq_enter/irq_exit dance in smp_reschedule_interrupt(). Suggested-by: Peter Zijlstra Suggested-by: Paolo Bonzini Signed-off-by: Wanpeng Li Acked-by: Paolo Bonzini Cc: kvm@vger.kernel.org Cc: Mike Galbraith Cc: Borislav Petkov Link: http://lkml.kernel.org/r/1478488420-5982-3-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Thomas Gleixner --- arch/x86/include/asm/apic.h | 3 ++- arch/x86/kernel/apic/apic.c | 1 + arch/x86/kernel/kvm.c | 4 ++-- arch/x86/kernel/smp.c | 2 -- 4 files changed, 5 insertions(+), 5 deletions(-) (limited to 'arch/x86/kernel') diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h index f5aaf6c83222..a5a0bcfde76a 100644 --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -196,7 +196,7 @@ static inline void native_apic_msr_write(u32 reg, u32 v) static inline void native_apic_msr_eoi_write(u32 reg, u32 v) { - wrmsr(APIC_BASE_MSR + (APIC_EOI >> 4), APIC_EOI_ACK, 0); + wrmsr_notrace(APIC_BASE_MSR + (APIC_EOI >> 4), APIC_EOI_ACK, 0); } static inline u32 native_apic_msr_read(u32 reg) @@ -332,6 +332,7 @@ struct apic { * on write for EOI. */ void (*eoi_write)(u32 reg, u32 v); + void (*native_eoi_write)(u32 reg, u32 v); u64 (*icr_read)(void); void (*icr_write)(u32 low, u32 high); void (*wait_icr_idle)(void); diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 88c657b057e2..2686894350a4 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -2263,6 +2263,7 @@ void __init apic_set_eoi_write(void (*eoi_write)(u32 reg, u32 v)) for (drv = __apicdrivers; drv < __apicdrivers_end; drv++) { /* Should happen once for each apic */ WARN_ON((*drv)->eoi_write == eoi_write); + (*drv)->native_eoi_write = (*drv)->eoi_write; (*drv)->eoi_write = eoi_write; } } diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index edbbfc854e39..aad52f1b0f9f 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -308,7 +308,7 @@ static void kvm_register_steal_time(void) static DEFINE_PER_CPU(unsigned long, kvm_apic_eoi) = KVM_PV_EOI_DISABLED; -static void kvm_guest_apic_eoi_write(u32 reg, u32 val) +static notrace void kvm_guest_apic_eoi_write(u32 reg, u32 val) { /** * This relies on __test_and_clear_bit to modify the memory @@ -319,7 +319,7 @@ static void kvm_guest_apic_eoi_write(u32 reg, u32 val) */ if (__test_and_clear_bit(KVM_PV_EOI_BIT, this_cpu_ptr(&kvm_apic_eoi))) return; - apic_write(APIC_EOI, APIC_EOI_ACK); + apic->native_eoi_write(APIC_EOI, APIC_EOI_ACK); } static void kvm_guest_cpu_init(void) diff --git a/arch/x86/kernel/smp.c b/arch/x86/kernel/smp.c index c00cb64bc0a1..68f8cc222f25 100644 --- a/arch/x86/kernel/smp.c +++ b/arch/x86/kernel/smp.c @@ -261,10 +261,8 @@ static inline void __smp_reschedule_interrupt(void) __visible void smp_reschedule_interrupt(struct pt_regs *regs) { - irq_enter(); ack_APIC_irq(); __smp_reschedule_interrupt(); - irq_exit(); /* * KVM uses this interrupt to force a cpu out of guest mode */ -- cgit v1.2.3