From 08306ce61d6848e6fbf74fa4cc693c3fb29e943f Mon Sep 17 00:00:00 2001 From: Cyrill Gorcunov Date: Sun, 12 Apr 2009 20:47:41 +0400 Subject: [PATCH] x86: apic - introduce dummy apic operations Impact: refactor, speed up and robustize code In case if apic was disabled by kernel option or by hardware limits we can use dummy operations in apic->write to simplify the ack_APIC_irq() code. At the lame time the patch fixes the missed EOI in do_IRQ function (which has place if kernel is compiled as X86-32 and interrupt without handler happens where apic was not asked to be disabled via kernel option). Note that native_apic_write_dummy() consists of WARN_ON_ONCE to catch any buggy writes on enabled APICs. Could be removed after some time of testing. Signed-off-by: Cyrill Gorcunov LKML-Reference: <20090412165058.724788431@openvz.org> Signed-off-by: Ingo Molnar --- arch/x86/include/asm/apic.h | 3 ++- arch/x86/kernel/apic/apic.c | 24 ++++++++++++++++++++++++ arch/x86/kernel/irq.c | 10 ++-------- 3 files changed, 28 insertions(+), 9 deletions(-) diff --git a/arch/x86/include/asm/apic.h b/arch/x86/include/asm/apic.h index 42f2f837742..2bd5a463fd1 100644 --- a/arch/x86/include/asm/apic.h +++ b/arch/x86/include/asm/apic.h @@ -212,6 +212,7 @@ static inline void ack_x2APIC_irq(void) } #endif +extern void apic_disable(void); extern int lapic_get_maxlvt(void); extern void clear_local_APIC(void); extern void connect_bsp_APIC(void); @@ -252,7 +253,7 @@ static inline void lapic_shutdown(void) { } #define local_apic_timer_c2_ok 1 static inline void init_apic_mappings(void) { } static inline void disable_local_APIC(void) { } - +static inline void apic_disable(void) { } #endif /* !CONFIG_X86_LOCAL_APIC */ #ifdef CONFIG_X86_64 diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index c3be10f5773..9b849d4957d 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -232,6 +232,24 @@ static int modern_apic(void) return lapic_get_version() >= 0x14; } +/* + * bare function to substitute write operation + * and it's _that_ fast :) + */ +void native_apic_write_dummy(u32 reg, u32 v) +{ + WARN_ON_ONCE((cpu_has_apic || !disable_apic)); +} + +/* + * right after this call apic->write doesn't do anything + * note that there is no restore operation it works one way + */ +void apic_disable(void) +{ + apic->write = native_apic_write_dummy; +} + void native_apic_wait_icr_idle(void) { while (apic_read(APIC_ICR) & APIC_ICR_BUSY) @@ -1582,6 +1600,12 @@ void __init init_apic_mappings(void) */ if (boot_cpu_physical_apicid == -1U) boot_cpu_physical_apicid = read_apic_id(); + + /* lets check if we may to NOP'ify apic operations */ + if (!cpu_has_apic) { + pr_info("APIC: disable apic facility\n"); + apic_disable(); + } } /* diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 6603492e8b7..fd57bf35d0f 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -27,7 +27,6 @@ void ack_bad_irq(unsigned int irq) if (printk_ratelimit()) pr_err("unexpected IRQ trap at vector %02x\n", irq); -#ifdef CONFIG_X86_LOCAL_APIC /* * Currently unexpected vectors happen only on SMP and APIC. * We _must_ ack these because every local APIC has only N @@ -37,9 +36,7 @@ void ack_bad_irq(unsigned int irq) * completely. * But only ack when the APIC is enabled -AK */ - if (cpu_has_apic) - ack_APIC_irq(); -#endif + ack_APIC_irq(); } #define irq_stats(x) (&per_cpu(irq_stat, x)) @@ -214,10 +211,7 @@ unsigned int __irq_entry do_IRQ(struct pt_regs *regs) irq = __get_cpu_var(vector_irq)[vector]; if (!handle_irq(irq, regs)) { -#ifdef CONFIG_X86_64 - if (!disable_apic) - ack_APIC_irq(); -#endif + ack_APIC_irq(); if (printk_ratelimit()) pr_emerg("%s: %d.%d No irq handler for vector (irq %d)\n", -- 2.39.3