Re: [PATCH] vfio/pci: zap_vma_ptes() needs MMU

[Alex Williamson]

On Sat, 15 May 2021 12:08:56 -0700
Randy Dunlap <rdunlap@xxxxxxxxxxxxx> wrote:

> zap_vma_ptes() is only available when CONFIG_MMU is set/enabled.
> Without CONFIG_MMU, vfio_pci.o has build errors, so make
> VFIO_PCI depend on MMU.
> 
> riscv64-linux-ld: drivers/vfio/pci/vfio_pci.o: in function `vfio_pci_mmap_open':
> vfio_pci.c:(.text+0x1ec): undefined reference to `zap_vma_ptes'
> riscv64-linux-ld: drivers/vfio/pci/vfio_pci.o: in function `.L0 ':
> vfio_pci.c:(.text+0x165c): undefined reference to `zap_vma_ptes'
> 
> Fixes: 89e1f7d4c66d ("vfio: Add PCI device driver")
> Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Cc: Alex Williamson <alex.williamson@xxxxxxxxxx>
> Cc: Cornelia Huck <cohuck@xxxxxxxxxx>
> Cc: kvm@xxxxxxxxxxxxxxx
> Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
> Cc: Eric Auger <eric.auger@xxxxxxxxxx>
> ---
>  drivers/vfio/pci/Kconfig |    1 +
>  1 file changed, 1 insertion(+)
> 
> --- linux-next-20210514.orig/drivers/vfio/pci/Kconfig
> +++ linux-next-20210514/drivers/vfio/pci/Kconfig
> @@ -2,6 +2,7 @@
>  config VFIO_PCI
>  	tristate "VFIO support for PCI devices"
>  	depends on VFIO && PCI && EVENTFD
> +	depends on MMU
>  	select VFIO_VIRQFD
>  	select IRQ_BYPASS_MANAGER
>  	help


Yes, these !MMU configs are getting annoying and I don't know of any
demand for vfio in them.  I suspect we were ok with !MMU until
11c4cd07ba11 though, that's where we added zap_vma_ptes usage.  I
updated the Fixes: tag but I suspect either case would reach the same
set of stable trees.  Applied to vfio for-linus branch for v5.13.
Thanks!

Alex