Re: [Qemu-devel] [PATCH] libqos: Solve bug in interrupt checking when using MSIX in virtio-pci.c

[John Snow]

On 02/24/2015 01:09 PM, John Snow wrote:
> On 02/24/2015 11:34 AM, Marc Marí wrote:
> > The MSIX interrupt was always acked without checking its value, which
> > caused a
> > race condition. If the ISR was raised between the read and the acking,
> > the ISR
> > was never detected and it timed out.
> >
> > Signed-off-by: Marc Marí <address@hidden>
> > ---
> >   tests/libqos/virtio-pci.c |   16 ++++++++++++----
> >   1 file changed, 12 insertions(+), 4 deletions(-)
> >
> > diff --git a/tests/libqos/virtio-pci.c b/tests/libqos/virtio-pci.c
> > index 788ebaf..c74a669 100644
> > --- a/tests/libqos/virtio-pci.c
> > +++ b/tests/libqos/virtio-pci.c
> > @@ -140,8 +140,12 @@ static bool
> > qvirtio_pci_get_queue_isr_status(QVirtioDevice *d, QVirtQueue *vq)
> >               return qpci_msix_pending(dev->pdev, vqpci->msix_entry);
> >           } else {
> >               data = readl(vqpci->msix_addr);
> > -            writel(vqpci->msix_addr, 0);
> > -            return data == vqpci->msix_data;
> > +            if (data == vqpci->msix_data) {
> > +                writel(vqpci->msix_addr, 0);
> > +                return true;
> > +            } else {
> > +                return false;
> > +            }
> >           }
> >       } else {
> >           return qpci_io_readb(dev->pdev, dev->addr +
> > QVIRTIO_ISR_STATUS) & 1;
> > @@ -160,8 +164,12 @@ static bool
> > qvirtio_pci_get_config_isr_status(QVirtioDevice *d)
> >               return qpci_msix_pending(dev->pdev,
> > dev->config_msix_entry);
> >           } else {
> >               data = readl(dev->config_msix_addr);
> > -            writel(dev->config_msix_addr, 0);
> > -            return data == dev->config_msix_data;
> > +            if (data == dev->config_msix_data) {
> > +                writel(dev->config_msix_addr, 0);
> > +                return true;
> > +            } else {
> > +                return false;
> > +            }
> >           }
> >       } else {
> >           return qpci_io_readb(dev->pdev, dev->addr +
> > QVIRTIO_ISR_STATUS) & 2;
>
> 1,600+ runs and no hang, thanks :)
>
> Tested-by: John Snow <address@hidden>
> Reviewed-by: John Snow <address@hidden>

Ping?

Still hitting this failure upstream.