Re: [PATCH v20 2/3] vfio-pci/zdev: Add a device feature for error information

[Farhan Ali]

On 7/17/2026 2:26 PM, Alex Williamson wrote:
> On Tue, 30 Jun 2026 09:55:52 -0700
> Farhan Ali <alifm@xxxxxxxxxxxxx> wrote:
>
> > For zPCI devices, we have platform specific error information. The platform
> > firmware provides this error information to the operating system in an
> > architecture specific mechanism. To enable recovery from userspace for
> > these devices, we want to expose this error information to userspace. Add a
> > new device feature to expose this information.
> >
> > Userspace needs to be provide a buffer of fixed size. This size is provided
> > to userspace via the VFIO_DEVICE_INFO_CAP_ZPCI_BASE capability.
> >
> > Reviewed-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
> > Reviewed-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
> > Signed-off-by: Farhan Ali <alifm@xxxxxxxxxxxxx>
> > ---
> >   arch/s390/include/asm/pci.h      |  2 ++
> >   arch/s390/pci/pci_event.c        | 19 ++++++++++++++
> >   drivers/vfio/pci/vfio_pci_core.c |  2 ++
> >   drivers/vfio/pci/vfio_pci_priv.h |  9 +++++++
> >   drivers/vfio/pci/vfio_pci_zdev.c | 45 ++++++++++++++++++++++++++++++--
> >   include/uapi/linux/vfio.h        | 23 ++++++++++++++++
> >   include/uapi/linux/vfio_zdev.h   |  2 ++
> >   7 files changed, 100 insertions(+), 2 deletions(-)
> >
> > diff --git a/arch/s390/include/asm/pci.h b/arch/s390/include/asm/pci.h
> > index 016386f7ef4a..88a125b92bdd 100644
> > --- a/arch/s390/include/asm/pci.h
> > +++ b/arch/s390/include/asm/pci.h
> > @@ -364,6 +364,8 @@ int zpci_clear_error_state(struct zpci_dev *zdev);
> >   int zpci_reset_load_store_blocked(struct zpci_dev *zdev);
> >   void zpci_start_mediated_recovery(struct zpci_dev *zdev);
> >   void zpci_stop_mediated_recovery(struct zpci_dev *zdev);
> > +int zpci_get_pending_error(struct zpci_dev *zdev,
> > +			   struct zpci_ccdf_err *ccdf);
> >   
> >   #ifdef CONFIG_NUMA
> >   
> > diff --git a/arch/s390/pci/pci_event.c b/arch/s390/pci/pci_event.c
> > index 8934b640a095..3ad16038e005 100644
> > --- a/arch/s390/pci/pci_event.c
> > +++ b/arch/s390/pci/pci_event.c
> > @@ -77,6 +77,25 @@ static int zpci_store_pci_error(struct pci_dev *pdev,
> >   	return 0;
> >   }
> >   
> > +int zpci_get_pending_error(struct zpci_dev *zdev,
> > +			   struct zpci_ccdf_err *ccdf)
> > +{
> > +	int head = 0;
> Nit, unnecessary initialization.
>
> Otherwise LGTM and I can drop the initialization on commit if there's
> no other reason for respin.  I think we just need a branch from Bjorn
> to base this on once he's happy with the PCI series.  Thanks,
>
> Alex

Hi Alex,

Bjorn has accepted the PCI patches and merged it to his pci/slot 
tree[1]. Would you be able to merge the vfio patches? I was able to 
apply these patches on 7.2-rc7 and didn't have any conflicts. But let me 
know if you need me to respin.

Thanks again for all your help reviewing this series.

Thanks

Farhan



> > +
> > +	guard(mutex)(&zdev->pending_errs_lock);
> > +
> > +	if (!zdev->pending_errs.count)
> > +		return -ENOMSG;
> > +
> > +	head = zdev->pending_errs.head % ZPCI_ERR_PENDING_MAX;
> > +	memcpy(ccdf, &zdev->pending_errs.err[head],
> > +	       sizeof(struct zpci_ccdf_err));
> > +	zdev->pending_errs.head++;
> > +	zdev->pending_errs.count--;
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(zpci_get_pending_error);
> > +
> >   void zpci_start_mediated_recovery(struct zpci_dev *zdev)
> >   {
> >   	guard(mutex)(&zdev->pending_errs_lock);