Messages in this thread | | | Date | Tue, 18 Jan 2022 18:45:04 +0100 | Subject | Re: [PATCH v2 23/30] vfio/pci: re-introduce CONFIG_VFIO_PCI_ZDEV | From | Pierre Morel <> |
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On 1/18/22 18:32, Matthew Rosato wrote: > On 1/18/22 12:20 PM, Pierre Morel wrote: >> >> >> On 1/14/22 21:31, Matthew Rosato wrote: >>> This was previously removed as unnecessary; while that was true, >>> subsequent >>> changes will make KVM an additional required component for >>> vfio-pci-zdev. >>> Let's re-introduce CONFIG_VFIO_PCI_ZDEV as now there is actually a >>> reason >>> to say 'n' for it (when not planning to CONFIG_KVM). >>> >>> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com> >>> --- >>> drivers/vfio/pci/Kconfig | 11 +++++++++++ >>> drivers/vfio/pci/Makefile | 2 +- >>> include/linux/vfio_pci_core.h | 2 +- >>> 3 files changed, 13 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig >>> index 860424ccda1b..fedd1d4cb592 100644 >>> --- a/drivers/vfio/pci/Kconfig >>> +++ b/drivers/vfio/pci/Kconfig >>> @@ -42,5 +42,16 @@ config VFIO_PCI_IGD >>> and LPC bridge config space. >>> To enable Intel IGD assignment through vfio-pci, say Y. >>> + >>> +config VFIO_PCI_ZDEV >>> + bool "VFIO PCI extensions for s390x KVM passthrough" >>> + depends on S390 && KVM >>> + default y >>> + help >>> + Support s390x-specific extensions to enable support for >>> enhancements >>> + to KVM passthrough capabilities, such as interpretive >>> execution of >>> + zPCI instructions. >>> + >>> + To enable s390x KVM vfio-pci extensions, say Y. >> >> In several patches we check on CONFIG_PCI (14,15,16,17 and 22) but we >> may have PCI without VFIO_PCI, wouldn't it be a problem? >> >> Here we define a new CONFIG entry and I have two questions: >> >> 1- there is no dependency on VFIO_PCI while the functionality is >> obviously based on VFIO_PCI > > It's not obvious from this diff, but this 'config VFIO_PCI_ZDEV' > statement is within an 'if VFIO_PCI' statement, just like VFIO_PCI_IGD > above -- so the dependency is there.
sorry, I remember now you already answered this to Christian last time.
> >> >> 2- Wouldn't it be possible to use this item and the single condition >> for the different checks we need through the new VFIO interpretation >> functionality. > > Possibly, but 1) we'd have to make linking arch/s390/kvm/pci.o dependent > on CONFIG_VFIO_PCI instead of CONFIG_PCI in patch 14 and 2) if the > relationship between CONFIG_VFIO_PCI and CONFIG_PCI were to ever change > (though I don't see why it would..), we would be broken because the > symbols we are referencing really require CONFIG_PCI (as they are > located in s390 PCI). >
Yes but VFIO_PCI_ZDEV depends on KVM, PCI and on VFIO_PCI Wouldn't a single config item for this new code be easier to manage and understand?
-- Pierre Morel IBM Lab Boeblingen
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