Re: [PATCH v9 21/25] iommu/io-pgtable-arm: Support io-pgtable-arm in the hypervisor

[Mostafa Saleh <smostafa@google.com>]

On Thu, Oct 15, 2026 at 08:26:45PM +0000, sashiko-bot@kernel.org wrote:
> Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
> - [Low] arch: layering violation by including SMMUv3 header in generic io-pgtable-arm.h
> --
> 
> commit 251567dd4618edfaa4984ef7282b71a0da331297
> Author: Mostafa Saleh <smostafa@google.com>
> 
> iommu/io-pgtable-arm: Support io-pgtable-arm in the hypervisor
> 
> To be able to populate the shadow stage-2 in the hypervisor, compile
> io-pgtable-arm object for the hypervisor. This requires the hypervisor
> to provide the iommu-pages allocator, redefine the address conversion
> helpers, and stub out the DMA API.
> 
> [ ... ]
> 
> > diff --git a/drivers/iommu/io-pgtable-arm.h b/drivers/iommu/io-pgtable-arm.h
> > index ba7cfdf7afa03..4278da41e406d 100644
> > --- a/drivers/iommu/io-pgtable-arm.h
> > +++ b/drivers/iommu/io-pgtable-arm.h
> > @@ -27,4 +27,13 @@
> >  #define ARM_LPAE_TCR_PS_48_BIT		0x5ULL
> >  #define ARM_LPAE_TCR_PS_52_BIT		0x6ULL
> >  
> > +#ifndef __KVM_NVHE_HYPERVISOR__
> > +#include "iommu-pages.h"
> > +#define arm_lpae_alloc_data(obj)	kmalloc_obj(obj)
> > +#define arm_lpae_free_data(p)		kfree(p)
> > +
> > +#else
> > +#include "arm/arm-smmu-v3/pkvm/io-pgtable-arm-hyp.h"
> 
> [Severity: Low]
> Is this an intended architecture layering violation? The generic ARM LPAE page
> table header drivers/iommu/io-pgtable-arm.h explicitly includes the
> driver-specific header arm/arm-smmu-v3/pkvm/io-pgtable-arm-hyp.h when
> compiled for the hypervisor. This tightly couples generic IOMMU framework code
> directly to the SMMUv3 driver path.
> 
> Should the hypervisor stubs be placed in a generic NVHE include directory
> (e.g., arch/arm64/kvm/hyp/include/nvhe/) to maintain subsystem independence,
> even if SMMUv3 is currently the only user?
> 

No strong opinion, I think keeping it anywhere under drivers/iommu is
fine.

Thanks,
Mostafa

> > +#endif
> > +
> >  #endif /* IO_PGTABLE_ARM_H_ */
> 
> -- 
> Sashiko AI review · https://sashiko.dev/#/patchset/20261015200903.2735565-1-smostafa@google.com?part=21