On Fri, Sep 04, 2026 at 10:13:18AM -0400, Andrew Stellman wrote:
> vp_interrupt() reads the ISR before dispatching config-change and
> vring handling. Reading the ISR also clears it, so once the read
> returns non-zero the interrupt was from this device and has already
> been consumed.
>
> Currently vp_interrupt() returns the result of vp_vring_interrupt().
> For a config-change interrupt with no vring work, that can return
> IRQ_NONE even though the ISR was non-zero and the interrupt was
> handled.
>
> Call vp_vring_interrupt() for any queue work, but once the ISR is
> non-zero return IRQ_HANDLED.
>
> Tested with QEMU virtio-blk-pci forced to INTx using vectors=0 and
> pci=nomsi. On an idle device, 200 config-change interrupts were
> generated using QMP block_resize.
>
> Before this change, irq_handler_exit reported ret=unhandled and
> /proc/irq/11/spurious increased from 0 to 200 unhandled interrupts.
> After this change, irq_handler_exit reported ret=handled and the
> unhandled count remained at 0.
>
> The issue was found during an LLM-assisted Quality Playbook review.
>
> Fixes: 77cf524654a8 ("virtio_pci: split up vp_interrupt")
this is still the wrong commit to blame.
> Suggested-by: Michael S. Tsirkin <[email protected]>
> Assisted-by: LLM
This is not the correct format. See Documentation.
> Signed-off-by: Andrew Stellman <[email protected]>
> ---
> Changes from v2:
> - Repost as a standalone patch in a new thread, per maintainer request.
> - Add LLM-assistance disclosure.
> - No code changes.
>
> Changes from v1:
> - Return IRQ_HANDLED for any non-zero ISR, as suggested by Michael.
> - Add Fixes and Suggested-by tags.
> - Test the change with virtio-blk forced to legacy INTx under QEMU.
>
> Full red/green test logs and the tested v2 patch:
> https://github.com/andrewstellman/quality-playbook/tree/11ba61d/evidence/virtio-pci-intx
>
> drivers/virtio/virtio_pci_common.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/virtio/virtio_pci_common.c
> b/drivers/virtio/virtio_pci_common.c
> index 10371ecbc054..b90c174450b2 100644
> --- a/drivers/virtio/virtio_pci_common.c
> +++ b/drivers/virtio/virtio_pci_common.c
> @@ -120,7 +120,9 @@ static irqreturn_t vp_interrupt(int irq, void *opaque)
> if (isr & VIRTIO_PCI_ISR_CONFIG)
> vp_config_changed(irq, opaque);
>
> - return vp_vring_interrupt(irq, opaque);
> + vp_vring_interrupt(irq, opaque);
> +
> + return IRQ_HANDLED;
> }
>
> static int vp_request_msix_vectors(struct virtio_device *vdev, int nvectors,
> base-commit: bc35965f6940a9bf834d54187b6088b8eb09206d
I already did exactly this in my tree, no further action is necessary,
but I will add your tested by tag.
Thanks!
> --
> 2.43.0
