Re: [PATCH V10 04/11] iommu/vt-d: Use helper function to skip agaw for SL

[Lu Baolu]

On 2020/3/28 0:05, Auger Eric wrote:
> Hi Jacob,
>
> On 3/27/20 12:55 PM, Tian, Kevin wrote:
> > > From: Jacob Pan<jacob.jun.pan@xxxxxxxxxxxxxxx>
> > > Sent: Saturday, March 21, 2020 7:28 AM
> > >
> > > Signed-off-by: Jacob Pan<jacob.jun.pan@xxxxxxxxxxxxxxx>
> > > ---
> > >   drivers/iommu/intel-pasid.c | 14 ++++----------
> > >   1 file changed, 4 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/drivers/iommu/intel-pasid.c b/drivers/iommu/intel-pasid.c
> > > index 191508c7c03e..9bdb7ee228b6 100644
> > > --- a/drivers/iommu/intel-pasid.c
> > > +++ b/drivers/iommu/intel-pasid.c
> > > @@ -544,17 +544,11 @@ int intel_pasid_setup_second_level(struct
> > > intel_iommu *iommu,
> > >   		return -EINVAL;
> > >   	}
> > >
> > > -	/*
> > > -	 * Skip top levels of page tables for iommu which has less agaw
> > > -	 * than default. Unnecessary for PT mode.
> > > -	 */
> > >   	pgd = domain->pgd;
> > > -	for (agaw = domain->agaw; agaw > iommu->agaw; agaw--) {
> > > -		pgd = phys_to_virt(dma_pte_addr(pgd));
> > > -		if (!dma_pte_present(pgd)) {
> > > -			dev_err(dev, "Invalid domain page table\n");
> > > -			return -EINVAL;
> > > -		}
> > > +	agaw = iommu_skip_agaw(domain, iommu, &pgd);
> > > +	if (agaw < 0) {
> > > +		dev_err(dev, "Invalid domain page table\n");
> is the dev_err() really requested. I see in domain_setup_first_level(),
> there is none.
> > > +		return -EINVAL;
> > >   	}
> > ok, I see how it is used. possibly combine last and this one together since
> > it's mostly moving code...
> I tend to agree with Kevin. May be better squash the 2 patches. Also not
> sure the inline of iommu_skip_agaw() is meaningful then. Also Add commit
> messages on the resulting patch.
>
> Note domain_setup_first_level() also could use the helper while we are
> it (if declaration moved to common helper). Only the error code differs
> in case !dma_pte_present(pgd), ie. -ENOMEM. May be good to align.
>
> Otherwise those stuff may be done in a fixup patch.

Agreed. Will squash these 2 patches with a meaningful commit message. As
for using this helper in other files, like domain_setup_first_level(),
we need more review and test efforts, hence it's better to put it in a
followup patch.

Best regards,
baolu