Re: [PATCH 1/8] iommu: Lift and generalize the STE/CD update code from SMMUv3

Jason Gunthorpe
2026-03-30T13:00:37Z

On Mon, Mar 09, 2026 at 11:33:23PM +0000, Samiullah Khawaja wrote:
> > + for (i = 0; i != writer->num_quantas; i++) {
> > + /*
> > + * Check that masks are up to date, the make functions are not
>
> nit: "the make functions" looks like a typo.

the smmu drivers called all the functions that build STE and CD
structs 'arm_smmu_make_xxx' So they are the 'make functions'

> > + } else if (used_qword_diff) {
> > + /*
> > + * At least two quantas need their inuse bits to be changed.
> > + * This requires a breaking update, zero the V bit, write all
> > + * qwords but 0, then set qword 0
> > + */
> > + unused_update[writer->vbit_quanta] = 0;
> > + NS(entry_set)(writer, entry, unused_update, writer->vbit_quanta, 1);
> > +
> > + if (writer->vbit_quanta != 0)
> > + NS(entry_set)(writer, entry, target, 0,
> > + writer->vbit_quanta - 1);
>
> Looking at the definition of the entry_set below, the last argument is
> length. So if vbit_quanta 1 then it would write zero len. Shouldn't it
> be writing quantas before the vbit_quanta?
> > + if (writer->vbit_quanta != writer->num_quantas)
> > + NS(entry_set)(writer, entry, target,
> > + writer->vbit_quanta,
> > + writer->num_quantas - 1);
>
> Sami here, the last argument should not have "- 1".

Yeah, I probably botched this when I quickly drafted it

Jason