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

["Raj, Ashok" <ashok.raj@intel.com>]

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);
>