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? 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." ?
