Re: [BUG] Continuously increasing spurious interrupts inside pSeries guest on PowerNV host

[Gautam Menghani <gautam@linux.ibm.com>]

On Fri, Aug 14, 2026 at 09:56:30AM -0500, Timothy Pearson wrote:
> With kernel 6.12 (Debian stable) we see a continuously increasing spurious interrupt count inside a pSeries guest running on a PowerNV host:
> 
> cat /proc/interrupts
>            CPU0
>  16:          0  XIVE-IPI   0 Edge      IPI-0
>  17:          0  XIVE-IRQ 4096 Edge      RAS_EPOW
>  21:          2  XIVE-IRQ 4353 Edge      hvc_console
>  23:          0  XIVE-IRQ 4097 Edge      RAS_HOTPLUG
>  24:          0  pSeries-PCI-MSI   0 Edge      virtio0-config
>  25:      50995  pSeries-PCI-MSI   1 Edge      virtio0-input.0
>  26:      45569  pSeries-PCI-MSI   2 Edge      virtio0-output.0
>  27:          0  pSeries-PCI-MSI 16384 Edge      virtio1-config
>  28:          6  pSeries-PCI-MSI 16385 Edge      virtio1-input
> LOC:       5781   Local timer interrupts for timer event device
> BCT:          0   Broadcast timer interrupts for timer event device
> LOC:          2   Local timer interrupts for others
> SPU:     449927   Spurious interrupts
> PMI:          0   Performance monitoring interrupts
> MCE:          0   Machine check exceptions
> NMI:          0   System Reset interrupts
> WDG:          0   Watchdog soft-NMI interrupts
> DBL:          0   Doorbell interrupts
> 
> The spurious interrupts are apparently from the virtio0-[input|output] devices.
> 

I was able to narrow it down to commit ecd10702baae5 ('KVM: PPC: Book3S HV: Handle pending exceptions on guest entry with MSR_EE')

Reverting the changes in this commit reduces the spurious interrupts
observed considerably. I'll try to root cause the issue and send a fix.

Thanks,
Gautam