Re: [PATCH v5 1/3] x86/iommu: remove regions not to be mapped

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, Jan 25, 2024 at 09:34:40AM +0100, Jan Beulich wrote:
> On 24.01.2024 18:29, Roger Pau Monne wrote:
> > --- a/xen/arch/x86/hvm/io.c
> > +++ b/xen/arch/x86/hvm/io.c
> > @@ -369,6 +369,22 @@ bool vpci_is_mmcfg_address(const struct domain *d, 
> > paddr_t addr)
> >      return vpci_mmcfg_find(d, addr);
> >  }
> >  
> > +int __hwdom_init vpci_subtract_mmcfg(const struct domain *d, struct 
> > rangeset *r)
> > +{
> > +    const struct hvm_mmcfg *mmcfg;
> > +
> > +    list_for_each_entry ( mmcfg, &d->arch.hvm.mmcfg_regions, next )
> > +    {
> > +        int rc = rangeset_remove_range(r, PFN_DOWN(mmcfg->addr),
> > +                                       PFN_DOWN(mmcfg->addr + mmcfg->size 
> > - 1));
> 
> Along the lines of this, ...
> 
> > --- a/xen/arch/x86/setup.c
> > +++ b/xen/arch/x86/setup.c
> > @@ -2138,6 +2138,54 @@ int __hwdom_init xen_in_range(unsigned long mfn)
> >      return 0;
> >  }
> >  
> > +int __hwdom_init remove_xen_ranges(struct rangeset *r)
> > +{
> > +    paddr_t start, end;
> > +    int rc;
> > +
> > +    /* S3 resume code (and other real mode trampoline code) */
> > +    rc = rangeset_remove_range(r, PFN_DOWN(bootsym_phys(trampoline_start)),
> > +                               PFN_DOWN(bootsym_phys(trampoline_end)) - 1);
> 
> ... did you perhaps mean
> 
>                                PFN_DOWN(bootsym_phys(trampoline_end) - 1));
> 
> here (and then similarly below, except there the difference is benign I
> think, for the labels being page-aligned)?

They are all page aligned, so I didn't care much,  but now that you
point it might be safer to do the subtraction from the address instead
of the frame number, just in case.

Thanks, Roger.