virtio-pci: return IRQ_HANDLED after non-zero ISR

Browse source

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: 77cf524654 ("virtio_pci: split up vp_interrupt")
Suggested-by: Michael S. Tsirkin <mst@redhat.com>
Assisted-by: LLM
Signed-off-by: Andrew Stellman <astellman@stellman-greene.com>
Message-ID: <20260904141318.30278-1-astellman@stellman-greene.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

...

This commit is contained in:

Andrew Stellman 2026-09-04 10:13:18 -04:00 • committed by Michael S. Tsirkin

parent 8dd505a45d

commit 93fa09455f

1 changed files with 3 additions and 1 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

4

drivers/virtio/virtio_pci_common.c

View file