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b4706d8149
During machine kexec, machine_kexec_mask_interrupts() is responsible for
disabling or masking all interrupts. While the irq_disable() is only
invoked when the interrupt is not yet disabled, it unconditionally invokes
the irq_mask() callback for every interrupt descriptor, even when the
interrupt is already masked or not even started up yet.
A specific issue was observed in the crash kernel flow after unbinding a
device (prior to kexec) that used a GPIO as an IRQ source. The warning was
triggered by the gpiochip_disable_irq() function, which attempts to clear
the FLAG_IRQ_IS_ENABLED flag when FLAG_USED_AS_IRQ was not set.
This issue surfaced after commit a8173820f4 ("gpio: gpiolib: Allow GPIO
IRQs to lazy disable") introduced lazy disablement for GPIO IRQs. It
replaced disable/enable hooks with mask/unmask hooks. Unlike the disable
hook, the mask hook doesn't handle already-masked IRQs.
When a GPIO-IRQ driver is unbound, the IRQ is released, triggering
__irq_disable() and irq_state_set_masked(). A subsequent call to
machine_kexec_mask_interrupts() re-invokes chip->irq_mask(). This results
in a call chain, including gpiochip_irq_mask() and gpiochip_disable_irq().
Since FLAG_USED_AS_IRQ was cleared earlier, the warning is triggered.
Replace the direct invocation of the irq_mask() and irq_disable() callbacks
invoking to irq_shutdown(), which handles the cases correct and avoid it
all together when the interrupt has never been started up.
Signed-off-by: Eliav Farber <farbere@amazon.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241204142003.32859-3-farbere@amazon.com
37 lines
870 B
C
37 lines
870 B
C
// SPDX-License-Identifier: GPL-2.0
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/irqdesc.h>
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#include <linux/irqnr.h>
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#include "internals.h"
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void machine_kexec_mask_interrupts(void)
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{
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struct irq_desc *desc;
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unsigned int i;
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for_each_irq_desc(i, desc) {
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struct irq_chip *chip;
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int check_eoi = 1;
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chip = irq_desc_get_chip(desc);
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if (!chip || !irqd_is_started(&desc->irq_data))
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continue;
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if (IS_ENABLED(CONFIG_GENERIC_IRQ_KEXEC_CLEAR_VM_FORWARD)) {
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/*
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* First try to remove the active state from an interrupt which is forwarded
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* to a VM. If the interrupt is not forwarded, try to EOI the interrupt.
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*/
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check_eoi = irq_set_irqchip_state(i, IRQCHIP_STATE_ACTIVE, false);
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}
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if (check_eoi && chip->irq_eoi && irqd_irq_inprogress(&desc->irq_data))
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chip->irq_eoi(&desc->irq_data);
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irq_shutdown(desc);
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}
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}
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