[PATCH kvmtool 3/4] virtio/pci: Deassert IRQ line on ISR read

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

Since commit 2108c86d0623 ("virtio/pci: Signal INTx interrupts as level
instead of edge"), virtio uses level-triggered IRQs. Bring the modern
device up to date, by deasserting the IRQ line when the guest reads the
interrupt status register.

Fixes: 3bf79498e6d5 ("virtio: Add support for modern virtio-pci")
Reported-by: Sami Mujawar <sami.mujawar@arm.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 virtio/pci-modern.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/virtio/pci-modern.c b/virtio/pci-modern.c
index 753e95bd..c5b4bc50 100644
--- a/virtio/pci-modern.c
+++ b/virtio/pci-modern.c
@@ -245,10 +245,7 @@ static bool virtio_pci__isr_read(struct virtio_device *vdev,
 		return false;
 
 	ioport__write8(data, vpci->isr);
-	/*
-	 * Interrupts are edge triggered (yes, going against the PCI and virtio
-	 * specs), so no need to deassert the IRQ line.
-	 */
+	kvm__irq_line(vpci->kvm, vpci->legacy_irq_line, VIRTIO_IRQ_LOW);
 	vpci->isr = 0;
 
 	return 0;
-- 
2.37.1