RE: [PATCH 15/17] IOMMU: page table dumping adjustments

["Tian, Kevin" <kevin.tian@xxxxxxxxx>]

> From: Jan Beulich <jbeulich@xxxxxxxx>
> Sent: Tuesday, August 24, 2021 10:29 PM
> 
> On 24.08.2021 16:26, Jan Beulich wrote:
> > For one none of the three IOMMU implementations on Arm specify a
> dumping
> > hook. Generalize VT-d's "don't dump shared page tables" to cover for
> > this.
> >
> > Further in the past I was told that on Arm in principle there could be
> > multiple different IOMMUs, and hence different domains' platform_ops
> > pointers could differ. Use each domain's ops for calling the dump hook.
> > (In the long run all uses of iommu_get_ops() would likely need to
> > disappear for this reason.)
> >
> > Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Should have Cc-ed Kevin on this one as well; now added.
> 
> Jan

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>

> 
> > --- a/xen/drivers/passthrough/iommu.c
> > +++ b/xen/drivers/passthrough/iommu.c
> > @@ -640,12 +640,9 @@ bool_t iommu_has_feature(struct domain *
> >  static void iommu_dump_page_tables(unsigned char key)
> >  {
> >      struct domain *d;
> > -    const struct iommu_ops *ops;
> >
> >      ASSERT(iommu_enabled);
> >
> > -    ops = iommu_get_ops();
> > -
> >      rcu_read_lock(&domlist_read_lock);
> >
> >      for_each_domain(d)
> > @@ -653,7 +650,13 @@ static void iommu_dump_page_tables(unsig
> >          if ( is_hardware_domain(d) || !is_iommu_enabled(d) )
> >              continue;
> >
> > -        ops->dump_page_tables(d);
> > +        if ( iommu_use_hap_pt(d) )
> > +        {
> > +            printk("%pd sharing page tables\n", d);
> > +            continue;
> > +        }
> > +
> > +        dom_iommu(d)->platform_ops->dump_page_tables(d);
> >      }
> >
> >      rcu_read_unlock(&domlist_read_lock);
> > --- a/xen/drivers/passthrough/vtd/iommu.c
> > +++ b/xen/drivers/passthrough/vtd/iommu.c
> > @@ -2835,12 +2835,6 @@ static void vtd_dump_page_tables(struct
> >  {
> >      const struct domain_iommu *hd = dom_iommu(d);
> >
> > -    if ( iommu_use_hap_pt(d) )
> > -    {
> > -        printk(VTDPREFIX " %pd sharing EPT table\n", d);
> > -        return;
> > -    }
> > -
> >      printk(VTDPREFIX" %pd table has %d levels\n", d,
> >             agaw_to_level(hd->arch.vtd.agaw));
> >      vtd_dump_page_table_level(hd->arch.vtd.pgd_maddr,
> >
> >