Re: [PATCH v2 1/3] 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: [email protected]
> Suggested-by: Long Li <[email protected]>
> Suggested-by: Thomas Gleixner <[email protected]>
> Reviewed-by: Aditya Garg <[email protected]>
> Reviewed-by: Shradha Gupta <[email protected]>
> Signed-off-by: Naman Jain <[email protected]>

Sashiko has reviewed this patch and found no issues. It looks great!

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