6.15-stable review patch. If anyone has any objections, please let me know.
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From: Thomas Gleixner tglx@linutronix.de
[ Upstream commit ce0b5eedcb753697d43f61dd2e27d68eb5d3150f ]
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") 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 Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/include/asm/hw_irq.h | 12 ++++--- arch/x86/kernel/irq.c | 63 ++++++++++++++++++++++++++--------- 2 files changed, 55 insertions(+), 20 deletions(-)
diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h index 162ebd73a698..cbe19e669080 100644 --- a/arch/x86/include/asm/hw_irq.h +++ b/arch/x86/include/asm/hw_irq.h @@ -92,8 +92,6 @@ struct irq_cfg {
extern struct irq_cfg *irq_cfg(unsigned int irq); extern struct irq_cfg *irqd_cfg(struct irq_data *irq_data); -extern void lock_vector_lock(void); -extern void unlock_vector_lock(void); #ifdef CONFIG_SMP extern void vector_schedule_cleanup(struct irq_cfg *); extern void irq_complete_move(struct irq_cfg *cfg); @@ -101,12 +99,16 @@ extern void irq_complete_move(struct irq_cfg *cfg); static inline void vector_schedule_cleanup(struct irq_cfg *c) { } static inline void irq_complete_move(struct irq_cfg *c) { } #endif - extern void apic_ack_edge(struct irq_data *data); -#else /* CONFIG_IRQ_DOMAIN_HIERARCHY */ +#endif /* CONFIG_IRQ_DOMAIN_HIERARCHY */ + +#ifdef CONFIG_X86_LOCAL_APIC +extern void lock_vector_lock(void); +extern void unlock_vector_lock(void); +#else static inline void lock_vector_lock(void) {} static inline void unlock_vector_lock(void) {} -#endif /* CONFIG_IRQ_DOMAIN_HIERARCHY */ +#endif
/* Statistics */ extern atomic_t irq_err_count; diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 6cd5d2d6c58a..3bdf9f9003c7 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -256,26 +256,59 @@ static __always_inline void handle_irq(struct irq_desc *desc, __handle_irq(desc, regs); }
-static __always_inline int call_irq_handler(int vector, struct pt_regs *regs) +static struct irq_desc *reevaluate_vector(int vector) { - struct irq_desc *desc; - int ret = 0; + 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 { - ret = -EINVAL; - 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; }
- return ret; + /* + * 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; }
/* @@ -289,7 +322,7 @@ 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");
- if (unlikely(call_irq_handler(vector, regs))) + if (unlikely(!call_irq_handler(vector, regs))) apic_eoi();
set_irq_regs(old_regs);