Re: [PATCH v2 7/8] xen/arm: Remove Linux specific code that is not usable in XEN

[Julien Grall <julien@xen.org>]

Hi Rahul,

On 03/12/2020 14:33, Rahul Singh wrote:
>> On 2 Dec 2020, at 2:45 pm, Julien Grall <julien@xen.org> wrote:
>>> -
>>> -static struct iommu_device *arm_smmu_probe_device(struct device *dev)
>>> -{
>>
>> Most of the code here looks useful to Xen. I think you want to keep the code and re-use it afterwards.
> 
> Ok. I removed the code here and added the XEN compatible code to add devices in next patch.
> I will keep it in this patch and will modifying the code to make XEN compatible.

In general, it is prefer if the code the code rather than dropping in 
patch A and then add it again differently patch B. This makes easier to 
check that the code outcome of the function is mostly the same.

>>> -static struct iommu_ops arm_smmu_ops = {
>>> -	.capable		= arm_smmu_capable,
>>> -	.domain_alloc		= arm_smmu_domain_alloc,
>>> -	.domain_free		= arm_smmu_domain_free,
>>> -	.attach_dev		= arm_smmu_attach_dev,
>>> -	.map			= arm_smmu_map,
>>> -	.unmap			= arm_smmu_unmap,
>>> -	.flush_iotlb_all	= arm_smmu_flush_iotlb_all,
>>> -	.iotlb_sync		= arm_smmu_iotlb_sync,
>>> -	.iova_to_phys		= arm_smmu_iova_to_phys,
>>> -	.probe_device		= arm_smmu_probe_device,
>>> -	.release_device		= arm_smmu_release_device,
>>> -	.device_group		= arm_smmu_device_group,
>>> -	.domain_get_attr	= arm_smmu_domain_get_attr,
>>> -	.domain_set_attr	= arm_smmu_domain_set_attr,
>>> -	.of_xlate		= arm_smmu_of_xlate,
>>> -	.get_resv_regions	= arm_smmu_get_resv_regions,
>>> -	.put_resv_regions	= generic_iommu_put_resv_regions,
>>> -	.pgsize_bitmap		= -1UL, /* Restricted during device attach */
>>> -};
>>> -
>>>   /* Probing and initialisation functions */
>>>   static int arm_smmu_init_one_queue(struct arm_smmu_device *smmu,
>>>   				   struct arm_smmu_queue *q,
>>> @@ -2406,7 +2032,6 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
>>>   	switch (FIELD_GET(IDR0_STALL_MODEL, reg)) {
>>>   	case IDR0_STALL_MODEL_FORCE:
>>>   		smmu->features |= ARM_SMMU_FEAT_STALL_FORCE;
>>> -		fallthrough;
>>
>> We should keep all the fallthrough documented. So I think we want to introduce the fallthrough in Xen as well.
> 
> Ok I will keep fallthrough documented in this patch.
> 
> fallthrough implementation in XEN should be another patch. I am not sure when we can implement but we will try to implement.

Yes, I didn't ask to implement "fallthrough" in this patch, but instead 
as a pre-requirement patch.

I would implement it in include/xen/compiler.h.

Cheers,

-- 
Julien Grall