Messages in this thread | | | Date | Tue, 18 Jan 2022 12:32:56 -0500 | Subject | Re: [PATCH v2 23/30] vfio/pci: re-introduce CONFIG_VFIO_PCI_ZDEV | From | Matthew Rosato <> |
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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.
> > 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).
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