From: Thomas Gleixner tglx@linutronix.de
Hogan reported a vector setup race, which overwrites the interrupt descriptor in the per CPU vector array resulting in a disfunctional device.
CPU0 CPU1 interrupt is raised in APIC IRR but not handled free_irq() per_cpu(vector_irq, CPU1)[vector] = VECTOR_SHUTDOWN;
request_irq() common_interrupt() d = this_cpu_read(vector_irq[vector]);
per_cpu(vector_irq, CPU1)[vector] = desc;
if (d == VECTOR_SHUTDOWN) this_cpu_write(vector_irq[vector], VECTOR_UNUSED);
free_irq() cannot observe the pending vector in the CPU1 APIC as there is no way to query the remote CPUs APIC IRR.
This requires that request_irq() uses the same vector/CPU as the one which was freed, but this also can be triggered by a spurious interrupt.
Interestingly enough this problem managed to be hidden for more than a decade.
Prevent this by reevaluating vector_irq under the vector lock, which is held by the interrupt activation code when vector_irq is updated.
To avoid ifdeffery or IS_ENABLED() nonsense, move the [un]lock_vector_lock() declarations out under the CONFIG_IRQ_DOMAIN_HIERARCHY guard as it's only provided when CONFIG_X86_LOCAL_APIC=y.
The current CONFIG_IRQ_DOMAIN_HIERARCHY guard is selected by CONFIG_X86_LOCAL_APIC, but can also be selected by other parts of the Kconfig system, which makes 32-bit UP builds with CONFIG_X86_LOCAL_APIC=n fail.
Can we just get rid of this !APIC nonsense once and forever?
Fixes: 9345005f4eed ("x86/irq: Fix do_IRQ() interrupt warning for cpu hotplug retriggered irqs") Cc: stable@vger.kernel.org#5.10.x Cc: gregkh@linuxfoundation.org Reported-by: Hogan Wang hogan.wang@huawei.com Signed-off-by: Thomas Gleixner tglx@linutronix.de Tested-by: Hogan Wang hogan.wang@huawei.com Link: https://lore.kernel.org/all/draft-87ikjhrhhh.ffs@tglx [ Conflicts in arch/x86/kernel/irq.c because call_irq_handler() has been refactored to do apic_eoi() according to the return value. Conflincts in arch/x86/include/asm/hw_irq.h because (un)lock_vector_lock() are already controlled by CONFIG_X86_LOCAL_APIC. ] Signed-off-by: Jinjie Ruan ruanjinjie@huawei.com --- arch/x86/kernel/irq.c | 65 +++++++++++++++++++++++++++++++++---------- 1 file changed, 51 insertions(+), 14 deletions(-)
diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 89e85664cb6d..344b2199d5b3 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -234,24 +234,59 @@ static __always_inline void handle_irq(struct irq_desc *desc, __handle_irq(desc, regs); }
-static __always_inline void call_irq_handler(int vector, struct pt_regs *regs) +static struct irq_desc *reevaluate_vector(int vector) { - struct irq_desc *desc; + struct irq_desc *desc = __this_cpu_read(vector_irq[vector]); + + if (!IS_ERR_OR_NULL(desc)) + return desc; + + if (desc == VECTOR_UNUSED) + pr_emerg_ratelimited("No irq handler for %d.%u\n", smp_processor_id(), vector); + else + __this_cpu_write(vector_irq[vector], VECTOR_UNUSED); + return NULL; +} + +static __always_inline bool call_irq_handler(int vector, struct pt_regs *regs) +{ + struct irq_desc *desc = __this_cpu_read(vector_irq[vector]);
- desc = __this_cpu_read(vector_irq[vector]); if (likely(!IS_ERR_OR_NULL(desc))) { handle_irq(desc, regs); - } else { - ack_APIC_irq(); - - if (desc == VECTOR_UNUSED) { - pr_emerg_ratelimited("%s: %d.%u No irq handler for vector\n", - __func__, smp_processor_id(), - vector); - } else { - __this_cpu_write(vector_irq[vector], VECTOR_UNUSED); - } + return true; } + + /* + * Reevaluate with vector_lock held to prevent a race against + * request_irq() setting up the vector: + * + * CPU0 CPU1 + * interrupt is raised in APIC IRR + * but not handled + * free_irq() + * per_cpu(vector_irq, CPU1)[vector] = VECTOR_SHUTDOWN; + * + * request_irq() common_interrupt() + * d = this_cpu_read(vector_irq[vector]); + * + * per_cpu(vector_irq, CPU1)[vector] = desc; + * + * if (d == VECTOR_SHUTDOWN) + * this_cpu_write(vector_irq[vector], VECTOR_UNUSED); + * + * This requires that the same vector on the same target CPU is + * handed out or that a spurious interrupt hits that CPU/vector. + */ + lock_vector_lock(); + desc = reevaluate_vector(vector); + unlock_vector_lock(); + + if (!desc) + return false; + + handle_irq(desc, regs); + return true; }
/* @@ -265,7 +300,9 @@ DEFINE_IDTENTRY_IRQ(common_interrupt) /* entry code tells RCU that we're not quiescent. Check it. */ RCU_LOCKDEP_WARN(!rcu_is_watching(), "IRQ failed to wake up RCU");
- call_irq_handler(vector, regs); + if (unlikely(!call_irq_handler(vector, regs))) + ack_APIC_irq(); + set_irq_regs(old_regs); }