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

----- Original Message -----

From: "Timothy Pearson" <redacted>
To: "linuxppc-dev" <redacted>
Cc: "Ritesh Harjani" <ritesh.list@gmail.com>
Sent: Friday, August 14, 2026 9:56:30 AM
Subject: [BUG] Continuously increasing spurious interrupts inside pSeries guest on PowerNV host

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.

Actually, I don't know where the spurious interrupts are coming from.  This is in XIVE mode.  Switching to XICS mode via -M pseries,ic-mode=xics greatly reduces the rate of spurious interrupts, but does not eliminate them.

I don't recall this being an issue on the 5.x series kernels, but do not have the ability to test either those or the 7.x series at the moment.