On 9/20/19 10:26 AM, Cornelia Huck wrote: > On Thu, 19 Sep 2019 16:57:10 -0400 > Matthew Rosato <mjrosato@xxxxxxxxxxxxx> wrote: > >> On 9/19/19 11:25 AM, Cornelia Huck wrote: >>> On Fri, 6 Sep 2019 20:13:51 -0400 >>> Matthew Rosato <mjrosato@xxxxxxxxxxxxx> wrote: >>> >>>> From: Pierre Morel <pmorel@xxxxxxxxxxxxx> >>>> >>>> We define a new configuration entry for VFIO/PCI, VFIO_PCI_ZDEV >>>> >>>> When the VFIO_PCI_ZDEV feature is configured we initialize >>>> a new device region, VFIO_REGION_SUBTYPE_ZDEV_CLP, to hold >>>> the information from the ZPCI device the use >>>> >>>> Signed-off-by: Pierre Morel <pmorel@xxxxxxxxxxxxx> >>>> Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx> >>>> --- >>>> drivers/vfio/pci/Kconfig | 7 +++ >>>> drivers/vfio/pci/Makefile | 1 + >>>> drivers/vfio/pci/vfio_pci.c | 9 ++++ >>>> drivers/vfio/pci/vfio_pci_private.h | 10 +++++ >>>> drivers/vfio/pci/vfio_pci_zdev.c | 85 +++++++++++++++++++++++++++++++++++++ >>>> 5 files changed, 112 insertions(+) >>>> create mode 100644 drivers/vfio/pci/vfio_pci_zdev.c >>>> >>>> diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig >>>> index ac3c1dd..d4562a8 100644 >>>> --- a/drivers/vfio/pci/Kconfig >>>> +++ b/drivers/vfio/pci/Kconfig >>>> @@ -45,3 +45,10 @@ config VFIO_PCI_NVLINK2 >>>> depends on VFIO_PCI && PPC_POWERNV >>>> help >>>> VFIO PCI support for P9 Witherspoon machine with NVIDIA V100 GPUs >>>> + >>>> +config VFIO_PCI_ZDEV >>>> + bool "VFIO PCI Generic for ZPCI devices" >>>> + depends on VFIO_PCI && S390 >>>> + default y >>>> + help >>>> + VFIO PCI support for S390 Z-PCI devices >>> >>> >From that description, I'd have no idea whether I'd want that or not. >>> Is there any downside to enabling it? >>> >> >> :) Not really, you're just getting information from the hardware vs >> using hard-coded defaults. The only reason I could think of to turn it >> off would be if you wanted/needed to restore this hard-coded behavior. > > I'm not really sure whether that's worth adding a Kconfig switch for. > Won't older versions simply ignore the new region anyway? > Yes, you have a point here... This switch showed up in v3 of this series when Pierre changed to using a region to pass this info and I haven't yet found a 'why' he decided to add the Kconfig switch. If I can't convince myself of a reason to keep it, I'll just remove it from the next version. > Also, I don't think we have any migration compatibility issues, as > vfio-pci devices are not (yet) migrateable anyway. > >> >> bool "VFIO PCI support for generic ZPCI devices" ? > > "Support zPCI-specific configuration for VFIO PCI" ? > >> >> "Support for sharing ZPCI hardware device information between the host >> and guests." ? > > "Enabling this options exposes a region containing hardware > configuration for zPCI devices. This enables userspace (e.g. QEMU) to > supply proper configuration values instead of hard-coded defaults for > zPCI devices passed through via VFIO on s390. > > Say Y here." > > ? > Your descriptions are much better - thanks for the feedback!
