From: Thomas Gleixner <tglx@linutronix.de>
commit ce0b5eedcb753697d43f61dd2e27d68eb5d3150f upstream.
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#5.15.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.
Conflicts 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 11d7233397df..065251fa3e40 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 __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;
}
/*
@@ -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);
}
--
2.34.1On Fri, Aug 22, 2025 at 03:36:08AM +0000, Jinjie Ruan wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
>
> commit ce0b5eedcb753697d43f61dd2e27d68eb5d3150f upstream.
>
> 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#5.15.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.
> Conflicts 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 11d7233397df..065251fa3e40 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 __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;
> }
>
> /*
> @@ -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);
> }
Same question here with this hunk, it seems like you are missing
something :(
thanks,
greg k-h
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