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

[Julien Grall <julien@xxxxxxx>]

Hi Rahul,

On 02/12/2020 14:34, Rahul Singh wrote:
> > >         dev_info(smmu->dev, "ias %lu-bit, oas %lu-bit (features 0x%08x)\n",
> > > @@ -2595,9 +2208,6 @@ static int arm_smmu_device_dt_probe(struct 
> > > platform_device *pdev,
> > >
> > >         parse_driver_options(smmu);
> > >
> > > -       if (of_dma_is_coherent(dev->of_node))
> > > -               smmu->features |= ARM_SMMU_FEAT_COHERENCY;
> > > -
> > Why this change? The ARM_SMMU_FEAT_COHERENCY flag is still used in
> > arm_smmu_device_hw_probe.
> I remove this as this is linux specific.  I will remove ARM_SMMU_FEAT_COHERENCY 
> flag  used in arm_smmu_device_hw_probe
From my understanding, ARM_SMMU_FEAT_COHERENCY indicate whether the 
SMMU page table walker will snoop the cache. If the flag is not set, 
then Xen will have to clean to PoC every entry updated in the p2m.
Therefore, I think we need to keep this code.

In the case we don't need to keep the code, then I think the reason 
should be explained in the commit message.
Cheers,

--
Julien Grall