On Wed, 12 Aug 2020 10:50:17 -0400 Matthew Rosato <[email protected]> wrote:
> s390x has the notion of providing VFs to the kernel in a manner > where the associated PF is inaccessible other than via firmware. > These are not treated as typical VFs and access to them is emulated > by underlying firmware which can still access the PF. After > abafbc55 however these detached VFs were no longer able to work > with vfio-pci as the firmware does not provide emulation of the > PCI_COMMAND_MEMORY bit. In this case, let's explicitly recognize > these detached VFs so that vfio-pci can allow memory access to > them again. > > Signed-off-by: Matthew Rosato <[email protected]> > Reviewed-by: Pierre Morel <[email protected]> > Reviewed-by: Niklas Schnelle <[email protected]> > --- > arch/s390/pci/pci.c | 8 ++++++++ > drivers/vfio/pci/vfio_pci_config.c | 3 ++- > include/linux/pci.h | 1 + > 3 files changed, 11 insertions(+), 1 deletion(-) > > diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c > index 3902c9f..04ac76d 100644 > --- a/arch/s390/pci/pci.c > +++ b/arch/s390/pci/pci.c > @@ -581,6 +581,14 @@ int pcibios_enable_device(struct pci_dev *pdev, int mask) > { > struct zpci_dev *zdev = to_zpci(pdev); > > + /* > + * If we have a VF on a non-multifunction bus, it must be a VF that is > + * detached from its parent PF. We rely on firmware emulation to > + * provide underlying PF details. > + */ > + if (zdev->vfn && !zdev->zbus->multifunction) > + pdev->detached_vf = 1; > + > zpci_debug_init_device(zdev, dev_name(&pdev->dev)); > zpci_fmb_enable_device(zdev); > > diff --git a/drivers/vfio/pci/vfio_pci_config.c > b/drivers/vfio/pci/vfio_pci_config.c > index d98843f..17845fc 100644 > --- a/drivers/vfio/pci/vfio_pci_config.c > +++ b/drivers/vfio/pci/vfio_pci_config.c > @@ -406,7 +406,8 @@ bool __vfio_pci_memory_enabled(struct vfio_pci_device > *vdev) > * PF SR-IOV capability, there's therefore no need to trigger > * faults based on the virtual value. > */ > - return pdev->is_virtfn || (cmd & PCI_COMMAND_MEMORY); > + return pdev->is_virtfn || pdev->detached_vf || > + (cmd & PCI_COMMAND_MEMORY); > } > > /* Wouldn't we also want to enable the is_virtfn related code in vfio_basic_config_read() and at least the initial setting of the command register in vfio_config_init()? Otherwise we're extending the incomplete emulation out to userspace. Thanks, Alex > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 8355306..23a6972 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -445,6 +445,7 @@ struct pci_dev { > unsigned int is_probed:1; /* Device probing in progress */ > unsigned int link_active_reporting:1;/* Device capable of reporting > link active */ > unsigned int no_vf_scan:1; /* Don't scan for VFs after IOV > enablement */ > + unsigned int detached_vf:1; /* VF without local PF access */ > pci_dev_flags_t dev_flags; > atomic_t enable_cnt; /* pci_enable_device has been called */ >
