On CPU hot-unplug, fixup_irqs() re-injects interrupts that are still pending in the outgoing CPU's IRR via the irqchip's irq_retrigger() callback. The Hyper-V root partition PCI/MSI irqchip lost that callback when it was converted to msi_create_parent_irq_domain(), so such a pending interrupt is silently dropped, leading to lost interrupts, stalls and "No irq handler for vector" messages.
Patch 1 is the minimal, backportable fix (Fixes:/Cc: stable) that restores irq_chip_retrigger_hierarchy() on the Hyper-V root partition PCI/MSI chip. The equivalent guest pci-hyperv.c fix from the previous version is already merged, so it is dropped here. Patch 2 then switches fixup_irqs() to have a fallback call to irq_chip_retrigger_hierarchy() directly, if a chip does not define irq_retrigger callback. Patch 3 makes a similar change in msi_set_affinity() Patch 4 then drops the now-redundant irq_retrigger() initializations. This way, patch 2-4 do not need to be backported. Changes since v3: https://lore.kernel.org/all/[email protected]/ * Move irq_retrigger setting to hv_init_dev_msi_info() in patch 1 (Michael, Nam) * Add if-else fallback check in msi_set_affinity() in patch 3 (Michael) * Break patch 3 into two separate patches, while *keeping review tags*. Changes since v2: https://lore.kernel.org/all/[email protected]/ * Add a backportable fix for Hyper-V root partition irqchip (Wei) * Add a check for custom irq_retrigger implementations and add direct irq_chip_retrigger_hierarchy() calls as a fallback if it is not defined by a chip. (Sashiko, Michael) * Removed local loop variable change, and continue using the irq_desc accessor function (Michael) * Did not pick "Acked-by: Manivannan Sadhasivam" as it was on v1, and v3 is a functionally different to some extent, specially patch 2. Requesting you to please review again. Changes since v1: https://lore.kernel.org/all/[email protected]/#t * Added Review tags * Adding minor clarification in commit msg of patch 2 (Shradha) Original RFC: https://lore.kernel.org/all/87y0f3jhd6.ffs@fw13/ Naman Jain (4): x86/hyperv: Set irq_retrigger for root partition PCI/MSI irqchip x86/irq: Fall back to irq_chip_retrigger_hierarchy() in fixup_irqs() x86/irq: Fall back to irq_chip_retrigger_hierarchy() in msi_set_affinity() x86/irq, iommu/amd, x86/hyperv, PCI: Drop redundant irq_retrigger inits arch/x86/kernel/apic/io_apic.c | 2 -- arch/x86/kernel/apic/msi.c | 12 ++++++++---- arch/x86/kernel/hpet.c | 1 - arch/x86/kernel/irq.c | 19 +++++++++++-------- drivers/iommu/amd/init.c | 1 - drivers/pci/controller/pci-hyperv.c | 1 - 6 files changed, 19 insertions(+), 17 deletions(-) base-commit: 944a035ecca915ae947905dcfb03f2b9dc6d032c -- 2.43.0
