[PATCH kernel v5 14/20] powerpc/powernv/npu: Add compound IOMMU groups

[Michael Ellerman]

Alexey Kardashevskiy <aik at ozlabs.ru> writes:
> On 19/12/2018 21:00, Michael Ellerman wrote:
>> Alexey Kardashevskiy <aik at ozlabs.ru> writes:
>>> On 19/12/2018 11:17, Michael Ellerman wrote:
>>>> Alexey Kardashevskiy <aik at ozlabs.ru> writes:
>>>>> diff --git a/arch/powerpc/platforms/powernv/npu-dma.c b/arch/powerpc/platforms/powernv/npu-dma.c
>>>>> index dc629ee..3468eaa 100644
>>>>> --- a/arch/powerpc/platforms/powernv/npu-dma.c
>>>>> +++ b/arch/powerpc/platforms/powernv/npu-dma.c
>>>>> @@ -372,8 +358,263 @@ struct npu {
>>>> ...
>>>>> +
>>>>> +static void pnv_comp_attach_table_group(struct npu_comp *npucomp,
>>>>> +		struct pnv_ioda_pe *pe)
>>>>> +{
>>>>> +	if (WARN_ON(npucomp->pe_num == NV_NPU_MAX_PE_NUM))
>>>>> +		return;
>>>>> +
>>>>> +	npucomp->pe[npucomp->pe_num] = pe;
>>>>> +	++npucomp->pe_num;
>>>>> +}
>>>>> +
>>>>> +struct iommu_table_group *pnv_try_setup_npu_table_group(struct pnv_ioda_pe *pe)
>>>>> +{
>>>>> +	struct iommu_table_group *table_group;
>>>>> +	struct npu_comp *npucomp;
>>>>> +	struct pci_dev *gpdev = NULL;
>>>>> +	struct pci_controller *hose;
>>>>> +	struct pci_dev *npdev;
>>>>> +
>>>>> +	list_for_each_entry(gpdev, &pe->pbus->devices, bus_list) {
>>>>> +		npdev = pnv_pci_get_npu_dev(gpdev, 0);
>>>>> +		if (npdev)
>>>>> +			break;
>>>>> +	}
>>>>> +
>>>>> +	if (!npdev)
>>>>> +		/* It is not an NPU attached device, skip */
>>>>> +		return NULL;
>>>>
>>>> This breaks some configs with:
>>>>
>>>>   arch/powerpc/platforms/powernv/npu-dma.c:550:5: error: 'npdev' may be used uninitialized in this function [-Werror=uninitialized]
>>>
>>>
>>> gcc 5, 7 and 8 do not warn about this, I have to disable
>>> list_for_each_entry() above to recreate this.
>>>
>>> I even compiled gcc 5.5 which some of your buildmachines use and yet no
>>> error on this:
>>>
>>> make O=/home/aik/pbuild/kernel-le/ KCFLAGS=-Werror=all ARCH=powerpc
>>> CROSS_COMPILE=/opt/cross/gcc-powerpc64le-linux-5.5.0-nolibc/bin/powerpc64le-linux-
>>> arch/powerpc/platforms/powernv/npu-dma.o
>> 
>> Odd. That error is from kisskb like the others.
>> 
>> http://kisskb.ellerman.id.au/kisskb/buildresult/13622793/
>> 
>> Seems it's GCC 4.6.3 that is producing that one. Not sure why newer
>> compilers aren't warning about it.
>> 
>> 
>> It's pretty obviously correct though, unless you can prove that the list
>> is never empty?
>
> I know these are correct and I want to catch these before I post patches :-/
>
> Can I get that gcc 4.6.3? It does not compile on my ubuntu for whatever
> reason.

It's the old korg one, it's on the ka's in /opt/cross.

It's this one:

https://mirrors.edge.kernel.org/pub/tools/crosstool/files/bin/x86_64/4.6.3/x86_64-gcc-4.6.3-nolibc_powerpc64-linux.tar.xz

cheers