From 86bdd16e8f390d51bae9e77a4bc4164ca2f580fe Mon Sep 17 00:00:00 2001 From: Naman Jain Date: Mon, 10 Aug 2026 09:07:13 +0000 Subject: [PATCH] PCI: hv: Set irq_retrigger callback for the Hyper-V PCI MSI irqchip The Hyper-V vPCI MSI irqchip never installs an irq_retrigger() callback. On CPU hot-unplug fixup_irqs() migrates the interrupts which are affine to the outgoing CPU to a new target. If an interrupt still has its pending bit set in the outgoing CPU's IRR at that point, fixup_irqs() resends it on the new target through the irqchip's irq_retrigger() callback. As the Hyper-V PCI/MSI chip does not provide that callback, the pending interrupt is silently dropped, which can result in lost interrupts, stalls and "No irq handler for vector" messages during CPU hotplug. Install irq_chip_retrigger_hierarchy() as the irq_retrigger() callback for the Hyper-V PCI/MSI irqchip, so that a pending interrupt is resent on its new target CPU via the parent x86 vector domain. Fixes: 4daace0d8ce85 ("PCI: hv: Add paravirtual PCI front-end for Microsoft Hyper-V VMs") Cc: stable@vger.kernel.org Suggested-by: Long Li Suggested-by: Thomas Gleixner Reviewed-by: Aditya Garg Reviewed-by: Shradha Gupta Signed-off-by: Naman Jain Reviewed-by: Michael Kelley Signed-off-by: Wei Liu --- drivers/pci/controller/pci-hyperv.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index cfc8fa403dad..89816a2bd7cd 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -2119,6 +2119,7 @@ static bool hv_pcie_init_dev_msi_info(struct device *dev, struct irq_domain *dom info->ops->msi_prepare = hv_msi_prepare; chip->irq_set_affinity = irq_chip_set_affinity_parent; + chip->irq_retrigger = irq_chip_retrigger_hierarchy; if (IS_ENABLED(CONFIG_X86)) chip->flags |= IRQCHIP_MOVE_DEFERRED;