* [BUG] Continuously increasing spurious interrupts inside pSeries guest on PowerNV host
@ 2026-08-14 14:56 Timothy Pearson
2026-08-14 15:14 ` Timothy Pearson
` (3 more replies)
0 siblings, 4 replies; 5+ messages in thread
From: Timothy Pearson @ 2026-08-14 14:56 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Ritesh Harjani
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.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [BUG] Continuously increasing spurious interrupts inside pSeries guest on PowerNV host
2026-08-14 14:56 [BUG] Continuously increasing spurious interrupts inside pSeries guest on PowerNV host Timothy Pearson
@ 2026-08-14 15:14 ` Timothy Pearson
2026-08-17 4:02 ` Madhavan Srinivasan
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Timothy Pearson @ 2026-08-14 15:14 UTC (permalink / raw)
To: linuxppc-dev; +Cc: Ritesh Harjani
----- Original Message -----
> From: "Timothy Pearson" <tpearson@raptorengineeringinc.com>
> To: "linuxppc-dev" <linuxppc-dev@lists.ozlabs.org>
> 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.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [BUG] Continuously increasing spurious interrupts inside pSeries guest on PowerNV host
2026-08-14 14:56 [BUG] Continuously increasing spurious interrupts inside pSeries guest on PowerNV host Timothy Pearson
2026-08-14 15:14 ` Timothy Pearson
@ 2026-08-17 4:02 ` Madhavan Srinivasan
2026-08-19 7:54 ` Gautam Menghani
2026-09-01 6:15 ` Gautam Menghani
3 siblings, 0 replies; 5+ messages in thread
From: Madhavan Srinivasan @ 2026-08-17 4:02 UTC (permalink / raw)
To: Timothy Pearson, linuxppc-dev; +Cc: Ritesh Harjani
On 8/14/26 8:26 PM, 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.
Thanks for the report Timothy, we will have a look at it.
Maddy
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [BUG] Continuously increasing spurious interrupts inside pSeries guest on PowerNV host
2026-08-14 14:56 [BUG] Continuously increasing spurious interrupts inside pSeries guest on PowerNV host Timothy Pearson
2026-08-14 15:14 ` Timothy Pearson
2026-08-17 4:02 ` Madhavan Srinivasan
@ 2026-08-19 7:54 ` Gautam Menghani
2026-09-01 6:15 ` Gautam Menghani
3 siblings, 0 replies; 5+ messages in thread
From: Gautam Menghani @ 2026-08-19 7:54 UTC (permalink / raw)
To: Timothy Pearson; +Cc: linuxppc-dev, Ritesh Harjani
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 am able to replicate this observation with KVM on PowerNV (XIVE):
1. Host and guest with kernel 6.19 (stock fedora kernels): Huge number of spurious interrupts
2. Host and guest with upstream kernel 5.19: A very small number of spurious
interrupts observed.
We'll look into this and post a fix.
Thanks,
Gautam
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [BUG] Continuously increasing spurious interrupts inside pSeries guest on PowerNV host
2026-08-14 14:56 [BUG] Continuously increasing spurious interrupts inside pSeries guest on PowerNV host Timothy Pearson
` (2 preceding siblings ...)
2026-08-19 7:54 ` Gautam Menghani
@ 2026-09-01 6:15 ` Gautam Menghani
3 siblings, 0 replies; 5+ messages in thread
From: Gautam Menghani @ 2026-09-01 6:15 UTC (permalink / raw)
To: Timothy Pearson; +Cc: linuxppc-dev, Ritesh Harjani
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
^ permalink raw reply [flat|nested] 5+ messages in thread
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2026-08-14 14:56 [BUG] Continuously increasing spurious interrupts inside pSeries guest on PowerNV host Timothy Pearson
2026-08-14 15:14 ` Timothy Pearson
2026-08-17 4:02 ` Madhavan Srinivasan
2026-08-19 7:54 ` Gautam Menghani
2026-09-01 6:15 ` Gautam Menghani
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