* [PATCH v5.15 1/2] x86/irq: Factor out handler invocation from common_interrupt()
2025-08-21 13:10 [PATCH v5.15 0/2] x86/irq: Plug vector setup race Jinjie Ruan
@ 2025-08-21 13:10 ` Jinjie Ruan
2025-08-21 13:10 ` [PATCH v5.15 2/2] x86/irq: Plug vector setup race Jinjie Ruan
1 sibling, 0 replies; 4+ messages in thread
From: Jinjie Ruan @ 2025-08-21 13:10 UTC (permalink / raw)
To: tglx, mingo, bp, dave.hansen, hpa, prarit, rui.y.wang, gregkh,
x86, stable, linux-kernel
Cc: ruanjinjie
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.com
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
^ permalink raw reply related [flat|nested] 4+ messages in thread* [PATCH v5.15 2/2] x86/irq: Plug vector setup race
2025-08-21 13:10 [PATCH v5.15 0/2] x86/irq: Plug vector setup race Jinjie Ruan
2025-08-21 13:10 ` [PATCH v5.15 1/2] x86/irq: Factor out handler invocation from common_interrupt() Jinjie Ruan
@ 2025-08-21 13:10 ` Jinjie Ruan
2025-08-21 13:21 ` kernel test robot
1 sibling, 1 reply; 4+ messages in thread
From: Jinjie Ruan @ 2025-08-21 13:10 UTC (permalink / raw)
To: tglx, mingo, bp, dave.hansen, hpa, prarit, rui.y.wang, gregkh,
x86, stable, linux-kernel
Cc: ruanjinjie
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#5.15.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.
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 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);
}
--
2.34.1
^ permalink raw reply related [flat|nested] 4+ messages in thread