Re: [PATCH] iommu: spapr_tce: Disable compile testing to fix build on book3s_32 config

[Michael Ellerman]

Christophe Leroy <christophe.leroy@xxxxxx> writes:
> On 04/14/2020 02:26 PM, Krzysztof Kozlowski wrote:
>> Although SPAPR_TCE_IOMMU itself can be compile tested on certain PowerPC
>> configurations, its presence makes arch/powerpc/kvm/Makefile to select
>> modules which do not build in such configuration.
>> 
>> The arch/powerpc/kvm/ modules use kvm_arch.spapr_tce_tables which exists
>> only with CONFIG_PPC_BOOK3S_64.  However these modules are selected when
>> COMPILE_TEST and SPAPR_TCE_IOMMU are chosen leading to build failures:
>> 
>>      In file included from arch/powerpc/include/asm/book3s/64/mmu-hash.h:20:0,
>>                       from arch/powerpc/kvm/book3s_64_vio_hv.c:22:
>>      arch/powerpc/include/asm/book3s/64/pgtable.h:17:0: error: "_PAGE_EXEC" redefined [-Werror]
>>       #define _PAGE_EXEC  0x00001 /* execute permission */
>> 
>>      In file included from arch/powerpc/include/asm/book3s/32/pgtable.h:8:0,
>>                       from arch/powerpc/include/asm/book3s/pgtable.h:8,
>>                       from arch/powerpc/include/asm/pgtable.h:18,
>>                       from include/linux/mm.h:95,
>>                       from arch/powerpc/include/asm/io.h:29,
>>                       from include/linux/io.h:13,
>>                       from include/linux/irq.h:20,
>>                       from arch/powerpc/include/asm/hardirq.h:6,
>>                       from include/linux/hardirq.h:9,
>>                       from include/linux/kvm_host.h:7,
>>                       from arch/powerpc/kvm/book3s_64_vio_hv.c:12:
>>      arch/powerpc/include/asm/book3s/32/hash.h:29:0: note: this is the location of the previous definition
>>       #define _PAGE_EXEC 0x200 /* software: exec allowed */
>> 
>> Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
>> Fixes: e93a1695d7fb ("iommu: Enable compile testing for some of drivers")
>> Signed-off-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx>
>> ---
>>   drivers/iommu/Kconfig | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
>> index 58b4a4dbfc78..3532b1ead19d 100644
>> --- a/drivers/iommu/Kconfig
>> +++ b/drivers/iommu/Kconfig
>> @@ -362,7 +362,7 @@ config IPMMU_VMSA
>>   
>>   config SPAPR_TCE_IOMMU
>>   	bool "sPAPR TCE IOMMU Support"
>> -	depends on PPC_POWERNV || PPC_PSERIES || (PPC && COMPILE_TEST)
>> +	depends on PPC_POWERNV || PPC_PSERIES
>>   	select IOMMU_API
>>   	help
>>   	  Enables bits of IOMMU API required by VFIO. The iommu_ops
>> 
>
> Should it be fixed the other way round, something like:

That doesn't actually fix this specific issue, the code will build but
then not link:

  ld: arch/powerpc/../../virt/kvm/vfio.o: in function `.kvm_spapr_tce_release_vfio_group':
  vfio.c:(.text.kvm_spapr_tce_release_vfio_group+0xb0): undefined reference to `.kvm_spapr_tce_release_iommu_group'
  ld: arch/powerpc/../../virt/kvm/vfio.o: in function `.kvm_vfio_set_group':
  vfio.c:(.text.kvm_vfio_set_group+0x7f4): undefined reference to `.kvm_spapr_tce_attach_iommu_group'
  ld: arch/powerpc/kvm/powerpc.o: in function `.kvm_arch_vm_ioctl':
  (.text.kvm_arch_vm_ioctl+0x1a4): undefined reference to `.kvm_vm_ioctl_create_spapr_tce'
  ld: (.text.kvm_arch_vm_ioctl+0x230): undefined reference to `.kvm_vm_ioctl_create_spapr_tce'
  make[1]: *** [/home/michael/linux/Makefile:1106: vmlinux] Error 1

> diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile
> index 2bfeaa13befb..906707d15810 100644
> --- a/arch/powerpc/kvm/Makefile
> +++ b/arch/powerpc/kvm/Makefile
> @@ -135,4 +135,4 @@ obj-$(CONFIG_KVM_BOOK3S_32) += kvm.o
>   obj-$(CONFIG_KVM_BOOK3S_64_PR) += kvm-pr.o
>   obj-$(CONFIG_KVM_BOOK3S_64_HV) += kvm-hv.o
>
> -obj-y += $(kvm-book3s_64-builtin-objs-y)
> +obj-$(CONFIG_KVM_BOOK3S_64) += $(kvm-book3s_64-builtin-objs-y)

But this is probably still a good thing to do, as it would have made the
error messages clearer in this case I think.

cheers