Re: [Xen-devel] [PATCH v6 08/10] remove late (on-demand) construction of IOMMU page tables

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich <jbeulich@xxxxxxxx>
> Sent: 29 August 2019 14:39
> To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Julien Grall <julien.grall@xxxxxxx>; 
> Alexandru Isaila
> <aisaila@xxxxxxxxxxxxxxx>; Petre Pircalabu <ppircalabu@xxxxxxxxxxxxxxx>; 
> Razvan Cojocaru
> <rcojocaru@xxxxxxxxxxxxxxx>; Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>; Roger 
> Pau Monne
> <roger.pau@xxxxxxxxxx>; Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>; 
> George Dunlap
> <George.Dunlap@xxxxxxxxxx>; Ian Jackson <Ian.Jackson@xxxxxxxxxx>; Stefano 
> Stabellini
> <sstabellini@xxxxxxxxxx>; KonradRzeszutek Wilk <konrad.wilk@xxxxxxxxxx>; 
> Tamas K Lengyel
> <tamas@xxxxxxxxxxxxx>; Tim (Xen.org) <tim@xxxxxxx>; Wei Liu <wl@xxxxxxx>
> Subject: Re: [PATCH v6 08/10] remove late (on-demand) construction of IOMMU 
> page tables
> 
> On 16.08.2019 19:19, Paul Durrant wrote:
> > --- a/xen/drivers/passthrough/iommu.c
> > +++ b/xen/drivers/passthrough/iommu.c
> > @@ -146,6 +146,17 @@ static int __init parse_dom0_iommu_param(const char *s)
> >  }
> >  custom_param("dom0-iommu", parse_dom0_iommu_param);
> >
> > +static void __hwdom_init check_hwdom_reqs(struct domain *d)
> 
> This really should have const, but I realize ...
> 
> > +{
> > +    if ( iommu_hwdom_none || !paging_mode_translate(d) )
> > +        return;
> > +
> > +    arch_iommu_check_autotranslated_hwdom(d);
> 
> ... this one wants non-const (for - afaict - no reason).
> 
> > @@ -159,129 +170,44 @@ int iommu_domain_init(struct domain *d)
> >          return ret;
> >
> >      hd->platform_ops = iommu_get_ops();
> > -    return hd->platform_ops->init(d);
> > -}
> > +    ret = hd->platform_ops->init(d);
> > +    if ( ret )
> > +        return ret;
> >
> > -static void __hwdom_init check_hwdom_reqs(struct domain *d)
> > -{
> > -    if ( iommu_hwdom_none || !paging_mode_translate(d) )
> > -        return;
> > +    /*
> > +     * NB: 'relaxed' h/w domains don't need the IOMMU mappings to be kept
> > +     *     in-sync with their assigned pages because all host RAM will be
> > +     *     mapped during hwdom_init().
> > +     */
> 
> Doesn't this comment belong to ...
> 
> > +    if ( is_hardware_domain(d) )
> > +        check_hwdom_reqs(d); /* may modify iommu_hwdom_strict */
> >
> > -    arch_iommu_check_autotranslated_hwdom(d);
> > +    if ( !is_hardware_domain(d) || iommu_hwdom_strict )
> > +        hd->need_sync = !iommu_use_hap_pt(d);
> 
> ... this if()?

Yes, it's probably adrift from where it should be now.

> 
> > @@ -629,8 +552,7 @@ static void iommu_dump_p2m_table(unsigned char key)
> >      ops = iommu_get_ops();
> >      for_each_domain(d)
> >      {
> > -        if ( is_hardware_domain(d) ||
> > -             dom_iommu(d)->status < IOMMU_STATUS_initialized )
> > +        if ( !is_iommu_enabled(d) )
> >              continue;
> 
> Didn't you agree to retain the hwdom part of the condition here?
> 

Indeed I have as of today, but this was posted 2 weeks ago :-)

  Paul

> Jan
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