Re: [PATCH] vfio/pci: Some buggy virtual functions incorrectly report 1 for intx.

Raj, Ashok
2018-09-12T17:47:48Z

On Thu, Aug 09, 2018 at 01:44:17PM -0600, Alex Williamson wrote:
> On Thu, 9 Aug 2018 12:37:06 -0700
> Ashok Raj <ashok.raj@intel.com> wrote:
>
> > PCI_INTERRUPT_PIN should always read 0 for SRIOV Virtual Functions.
> >
> > Some SRIOV devices have some bugs in RTL and VF's end up reading 1
> > instead of 0 for the PIN.
>
> Hi Ashok,
>
> One question, can we identify which VFs are known to have this issue so
> that users (and downstreams) can know how to prioritize this patch?

Hi Alex

Sorry it took some time to hunt this down.

The offending VF has a device ID : 0x270C
The corresponding PF has a device ID: 0x270B.

> Thanks,
>
> Alex
>
> > Since this is a spec required value, rather than having a device specific
> > quirk, we could fix it permanently in vfio.
> >
> > Reworked suggestions from Alex https://lkml.org/lkml/2018/7/16/1052
> >
> > Reported-by: Gage Eads <gage.eads@intel.com>
> > Tested-by: Gage Eads <gage.eads@intel.com>
> > Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> > Cc: kvm@vger.kernel.org
> > Cc: linux-kernel@vger.kernel.org
> > Cc: iommu@lists.linux-foundation.org
> > Cc: Joerg Roedel <joro@8bytes.org>
> > Cc: Bjorn Helgaas <helgaas@kernel.org>
> > Cc: Gage Eads <gage.eads@intel.com>
> > ---
> > drivers/vfio/pci/vfio_pci.c | 12 +++++++++---
> > drivers/vfio/pci/vfio_pci_config.c | 3 ++-
> > 2 files changed, 11 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> > index b423a30..32943dd 100644
> > --- a/drivers/vfio/pci/vfio_pci.c
> > +++ b/drivers/vfio/pci/vfio_pci.c
> > @@ -433,10 +433,16 @@ static int vfio_pci_get_irq_count(struct vfio_pci_device *vdev, int irq_type)
> > {
> > if (irq_type == VFIO_PCI_INTX_IRQ_INDEX) {
> > u8 pin;
> > - pci_read_config_byte(vdev->pdev, PCI_INTERRUPT_PIN, &pin);
> > - if (IS_ENABLED(CONFIG_VFIO_PCI_INTX) && !vdev->nointx && pin)
> > - return 1;
> > + /*
> > + * INTx must be 0 for all VF's. Enforce that for all
> > + * VF's since this is a spec requirement.
> > + */
> > + if (!IS_ENABLED(CONFIG_VFIO_PCI_INTX) || vdev->nointx ||
> > + vdev->pdev->is_virtfn)
> > + return 0;
> >
> > + pci_read_config_byte(vdev->pdev, PCI_INTERRUPT_PIN, &pin);
> > + return (pin ? 1 : 0);
> > } else if (irq_type == VFIO_PCI_MSI_IRQ_INDEX) {
> > u8 pos;
> > u16 flags;
> > diff --git a/drivers/vfio/pci/vfio_pci_config.c b/drivers/vfio/pci/vfio_pci_config.c
> > index 115a36f..e36b7c3 100644
> > --- a/drivers/vfio/pci/vfio_pci_config.c
> > +++ b/drivers/vfio/pci/vfio_pci_config.c
> > @@ -1676,7 +1676,8 @@ int vfio_config_init(struct vfio_pci_device *vdev)
> > *(__le16 *)&vconfig[PCI_DEVICE_ID] = cpu_to_le16(pdev->device);
> > }
> >
> > - if (!IS_ENABLED(CONFIG_VFIO_PCI_INTX) || vdev->nointx)
> > + if (!IS_ENABLED(CONFIG_VFIO_PCI_INTX) || vdev->nointx ||
> > + pdev->is_virtfn)
> > vconfig[PCI_INTERRUPT_PIN] = 0;
> >
> > ret = vfio_cap_init(vdev);
>