On Wed, Oct 22, 2014 at 11:17:11AM -0600, Alex Williamson wrote:
> On Wed, 2014-10-22 at 17:13 +0200, Frank Blaschka wrote:
> > From: Frank Blaschka <frank.blasc...@de.ibm.com>
> >
> > Let the kernel announce if INTx is available. Yes, there are platforms
> > (e.g. s390) which do not support INTx.
> >
> > Signed-off-by: Frank Blaschka <frank.blasc...@de.ibm.com>
> > ---
> > hw/misc/vfio.c | 18 +++++++++++++++++-
> > 1 file changed, 17 insertions(+), 1 deletion(-)
> >
> > diff --git a/hw/misc/vfio.c b/hw/misc/vfio.c
> > index d66f3d2..3e9600b 100644
> > --- a/hw/misc/vfio.c
> > +++ b/hw/misc/vfio.c
> > @@ -109,6 +109,7 @@ typedef struct VFIOVGA {
> > } VFIOVGA;
> >
> > typedef struct VFIOINTx {
> > + bool available; /* intx available */
> > bool pending; /* interrupt pending */
> > bool kvm_accel; /* set when QEMU bypass through KVM enabled */
> > uint8_t pin; /* which pin to pull for qemu_set_irq */
> > @@ -554,7 +555,7 @@ static int vfio_enable_intx(VFIODevice *vdev)
> > struct vfio_irq_set *irq_set;
> > int32_t *pfd;
> >
> > - if (!pin) {
> > + if (!pin || !vdev->intx.available) {
> > return 0;
> > }
> >
> > @@ -4032,6 +4033,21 @@ static int vfio_get_device(VFIOGroup *group, const
> > char *name, VFIODevice *vdev)
> > vdev->host.function);
> > }
> >
> > + irq_info.index = VFIO_PCI_INTX_IRQ_INDEX;
> > + ret = ioctl(vdev->fd, VFIO_DEVICE_GET_IRQ_INFO, &irq_info);
> > + if (ret) {
> > + /*
> > + * This can fail for an old kernel or legacy PCI dev
> > + * we assume intx is available
> > + */
>
> Is this true? It's unfortunately from an ABI stability standpoint that
> we weren't calling this, but the ioctl should have always been there and
> worked. I'd rather error out here than add a fallback if this is just
ok
> paranoia. Note that SR-IOV VFs will also report count=0 but their IRQ
> pin register will read 0. We do also have the option to virtualize the
> IRQ pin register for s390 devices which would make them look the same as
sounds interesting, can you elaborate a little bit more on this?
At what point can we hook in and modify the pci device config space?
> an SR-IOV VF from an INTx perspective to the user. That may be the more
> consistent option so that the VFIO IRQ INFO aligns with config space.
> Thanks,
>
> Alex
>
> > + vdev->intx.available = true;
> > + ret = 0;
> > + } else if (irq_info.count == 0) {
> > + vdev->intx.available = false;
> > + } else {
> > + vdev->intx.available = true;
> > + }
> > +
> > error:
> > if (ret) {
> > QLIST_REMOVE(vdev, next);
>
>
>
>
