[PATCH v5.15 0/2] x86/irq: Plug vector setup race
There is 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. Fixes: 9345005f4eed ("x86/irq: Fix do_IRQ() interrupt warning for cpu hotplug retriggered irqs") Cc: stable@vger.kernel.org#5.15.x Cc: gregkh@linuxfoundation.org Jacob Pan (1): x86/irq: Factor out handler invocation from common_interrupt() Thomas Gleixner (1): x86/irq: Plug vector setup race arch/x86/kernel/irq.c | 70 ++++++++++++++++++++++++++++++++++--------- 1 file changed, 56 insertions(+), 14 deletions(-) -- 2.34.1
From: Jacob Pan <jacob.jun.pan@linux.intel.com> Prepare for calling external interrupt handlers directly from the posted MSI demultiplexing loop. Extract the common code from common_interrupt() to avoid code duplication. Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Link: https://lore.kernel.org/r/20240423174114.526704-8-jacob.jun.pan@linux.intel.... Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com> --- arch/x86/kernel/irq.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 439fdb3f5fdf..11d7233397df 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -235,18 +235,10 @@ static __always_inline void handle_irq(struct irq_desc *desc, __handle_irq(desc, regs); } -/* - * common_interrupt() handles all normal device IRQ's (the special SMP - * cross-CPU interrupts have their own entry points). - */ -DEFINE_IDTENTRY_IRQ(common_interrupt) +static __always_inline void call_irq_handler(int vector, struct pt_regs *regs) { - struct pt_regs *old_regs = set_irq_regs(regs); struct irq_desc *desc; - /* entry code tells RCU that we're not quiescent. Check it. */ - RCU_LOCKDEP_WARN(!rcu_is_watching(), "IRQ failed to wake up RCU"); - desc = __this_cpu_read(vector_irq[vector]); if (likely(!IS_ERR_OR_NULL(desc))) { handle_irq(desc, regs); @@ -261,7 +253,20 @@ DEFINE_IDTENTRY_IRQ(common_interrupt) __this_cpu_write(vector_irq[vector], VECTOR_UNUSED); } } +} + +/* + * common_interrupt() handles all normal device IRQ's (the special SMP + * cross-CPU interrupts have their own entry points). + */ +DEFINE_IDTENTRY_IRQ(common_interrupt) +{ + struct pt_regs *old_regs = set_irq_regs(regs); + + /* 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); set_irq_regs(old_regs); } -- 2.34.1
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#6.6.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 | 63 ++++++++++++++++++++++++++++++++++--------- 1 file changed, 50 insertions(+), 13 deletions(-) diff --git a/arch/x86/kernel/irq.c b/arch/x86/kernel/irq.c index 11d7233397df..27c4b47ff6c4 100644 --- a/arch/x86/kernel/irq.c +++ b/arch/x86/kernel/irq.c @@ -235,24 +235,59 @@ static __always_inline void handle_irq(struct irq_desc *desc, __handle_irq(desc, regs); } +static struct irq_desc *reevaluate_vector(int vector) +{ + 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 void call_irq_handler(int vector, struct pt_regs *regs) { - struct irq_desc *desc; + 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; } /* @@ -266,7 +301,9 @@ 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); } -- 2.34.1
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Jinjie Ruan