Re: [PATCH v8 04/25] iommu/arm-smmu-v3: Move IDR parsing to common functions

[Mostafa Saleh <smostafa@google.com>]

On Tue, Sep 22, 2026 at 06:48:18PM -0300, Jason Gunthorpe wrote:
> On Tue, Sep 22, 2026 at 12:45:20PM -0700, Nicolin Chen wrote:
> 
> > Also, Jason's suggestion in v7 was hyp_arm_smmu_v3_device, which
> > looks nicer than ARM_SMMU_OBJ...
> 
> I guess the point is to emphasis the substition technique, I don't
> mind.
> 
> > > +	if (coherent && !disable_msipolling &&
> > > +	    smmu->features & ARM_SMMU_FEAT_MSI)
> > > +		smmu->options |= ARM_SMMU_OPT_MSIPOLL;
> > 
> > Will pKVM ever use MSIPOLL?
> 
> Not sure I understood the approach in this patch, why was anything
> left behind? I imagined everything would be moved?
> 
> Maybe a few more remarks in the commit message?

As replied to Nicolin, because it is a module param, I am ok with
adding this in the commit message, or passing disable_msipolling
as a function arg and moving the logic.

> 
> > > +	if (smmu->features & ARM_SMMU_FEAT_HYP &&
> > > +	    cpus_have_cap(ARM64_HAS_VIRT_HOST_EXTN))
> > > +		smmu->features |= ARM_SMMU_FEAT_E2H;
> > 
> > Why is ARM64_HAS_VIRT_HOST_EXTN left behind?
> 
> +1
> 
> And the TT_LE/BE and S1/S2 checks, and ...
> 
> If kvm doesn't want to dev_err log that's fine, we should able to
> #define that away too shouldn't we? And maybe it does want to log?

The hypervisor can not print to the kernel console, so dev_err()
will not compile, I'd rather keep that outside and let the caller
decide what is a probe failure and print it's own message that keeping
the code and stubbing dev_err().

Thanks,
Mostafa

> 
> This seems pretty close otherwise
> 
> Jason