x86/ioapic: Cleanup the timer_works() irqflags mess
From: Thomas Gleixner <hidden>
Date: 2020-12-10 20:16:26
Also in:
lkml, xen-devel
Mark tripped over the creative irqflags handling in the IO-APIC timer
delivery check which ends up doing:
local_irq_save(flags);
local_irq_enable();
local_irq_restore(flags);
which triggered a new consistency check he's working on required for
replacing the POPF based restore with a conditional STI.
That code is a historical mess and none of this is needed. Make it
straightforward use local_irq_disable()/enable() as that's all what is
required. It is invoked from interrupt enabled code nowadays.
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Thomas Gleixner <redacted>
Tested-by: Mark Rutland <mark.rutland@arm.com>
---
arch/x86/kernel/apic/io_apic.c | 22 ++++++----------------
1 file changed, 6 insertions(+), 16 deletions(-)
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c@@ -1618,21 +1618,16 @@ static void __init delay_without_tsc(voi static int __init timer_irq_works(void) { unsigned long t1 = jiffies; - unsigned long flags; if (no_timer_check) return 1; - local_save_flags(flags); local_irq_enable(); - if (boot_cpu_has(X86_FEATURE_TSC)) delay_with_tsc(); else delay_without_tsc(); - local_irq_restore(flags); - /* * Expect a few ticks at least, to be sure some possible * glue logic does not lock up after one or two first
@@ -1641,10 +1636,10 @@ static int __init timer_irq_works(void) * least one tick may be lost due to delays. */ - /* jiffies wrap? */ - if (time_after(jiffies, t1 + 4)) - return 1; - return 0; + local_irq_disable(); + + /* Did jiffies advance? */ + return time_after(jiffies, t1 + 4); } /*
@@ -2117,13 +2112,12 @@ static inline void __init check_timer(vo struct irq_cfg *cfg = irqd_cfg(irq_data); int node = cpu_to_node(0); int apic1, pin1, apic2, pin2; - unsigned long flags; int no_pin1 = 0; if (!global_clock_event) return; - local_irq_save(flags); + local_irq_disable(); /* * get/set the timer IRQ vector:
@@ -2191,7 +2185,6 @@ static inline void __init check_timer(vo goto out; } panic_if_irq_remap("timer doesn't work through Interrupt-remapped IO-APIC"); - local_irq_disable(); clear_IO_APIC_pin(apic1, pin1); if (!no_pin1) apic_printk(APIC_QUIET, KERN_ERR "..MP-BIOS bug: "
@@ -2215,7 +2208,6 @@ static inline void __init check_timer(vo /* * Cleanup, just in case ... */ - local_irq_disable(); legacy_pic->mask(0); clear_IO_APIC_pin(apic2, pin2); apic_printk(APIC_QUIET, KERN_INFO "....... failed.\n");
@@ -2232,7 +2224,6 @@ static inline void __init check_timer(vo apic_printk(APIC_QUIET, KERN_INFO "..... works.\n"); goto out; } - local_irq_disable(); legacy_pic->mask(0); apic_write(APIC_LVT0, APIC_LVT_MASKED | APIC_DM_FIXED | cfg->vector); apic_printk(APIC_QUIET, KERN_INFO "..... failed.\n");
@@ -2251,7 +2242,6 @@ static inline void __init check_timer(vo apic_printk(APIC_QUIET, KERN_INFO "..... works.\n"); goto out; } - local_irq_disable(); apic_printk(APIC_QUIET, KERN_INFO "..... failed :(.\n"); if (apic_is_x2apic_enabled()) apic_printk(APIC_QUIET, KERN_INFO
@@ -2260,7 +2250,7 @@ static inline void __init check_timer(vo panic("IO-APIC + timer doesn't work! Boot with apic=debug and send a " "report. Then try booting with the 'noapic' option.\n"); out: - local_irq_restore(flags); + local_irq_enable(); } /*
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