Re: [Xen-devel] [PATCH v12 3/3] iommu: add rmrr Xen command line option for extra rmrrs

[Elena Ufimtseva <elena.ufimtseva@xxxxxxxxxx>]

On Wed, Oct 28, 2015 at 10:05:31AM -0600, Jan Beulich wrote:
> >>> On 27.10.15 at 21:36, <elena.ufimtseva@xxxxxxxxxx> wrote:
> > +static void __init add_extra_rmrr(void)
> > +{
> > +    struct acpi_rmrr_unit *acpi_rmrr;
> > +    struct acpi_rmrr_unit *rmrru;
> > +    unsigned int dev, seg, i;
> > +    unsigned long pfn;
> > +    bool_t overlap;
> > +
> > +    for ( i = 0; i < nr_rmrr; i++ )
> > +    {
> > +        if ( extra_rmrr_units[i].base_pfn > extra_rmrr_units[i].end_pfn )
> > +        {
> > +            printk(XENLOG_ERR VTDPREFIX
> > +                   "Invalid RMRR Range "ERMRRU_FMT"\n",
> > +                   ERMRRU_ARG(extra_rmrr_units[i]));
> > +            continue;
> > +        }
> > +
> > +        if ( extra_rmrr_units[i].end_pfn - extra_rmrr_units[i].base_pfn >=
> > +             MAX_EXTRA_RMRR_PAGES )
> > +        {
> > +            printk(XENLOG_ERR VTDPREFIX
> > +                   "RMRR range "ERMRRU_FMT" exceeds 
> > "__stringify(MAX_EXTRA_RMRR_PAGES)" pages\n",
> > +                   ERMRRU_ARG(extra_rmrr_units[i]));
> > +            continue;
> > +        }
> > +
> > +        overlap = 0;
> > +        list_for_each_entry(rmrru, &acpi_rmrr_units, list)
> > +        {
> > +            if ( pfn_to_paddr(extra_rmrr_units[i].base_pfn) < 
> > rmrru->end_address &&
> > +                 rmrru->base_address < 
> > pfn_to_paddr(extra_rmrr_units[i].end_pfn + 1) )
> 
> Aren't both ranges inclusive? I.e. shouldn't the first one be <= (and
> the second one could be <= too when dropping the +1), matching
> the check acpi_parse_one_rmrr() does?

The end_address is not inclusive, while the start_address is.
These to from  rmrr_identity_mapping()
    ...
    ASSERT(rmrr->base_address < rmrr->end_address);                             
and:
    ...
    while ( base_pfn < end_pfn )
    {
        int err = set_identity_p2m_entry(d, base_pfn, p2m_access_rw, flag);
                                                                                
        if ( err )                                                              
            return err;                                                         
        base_pfn++;                                                             
    }
    ...

I think this condition should not be a problem. But yes, its not uniform with 
acpi_parse_one_rmrr.
I guess I should send another version then?
> 
> > +            {
> > +                printk(XENLOG_ERR VTDPREFIX
> > +                       "Overlapping RMRRs: "ERMRRU_FMT" and [%lx-%lx]\n",
> > +                       ERMRRU_ARG(extra_rmrr_units[i]),
> > +                       paddr_to_pfn(rmrru->base_address),
> > +                       paddr_to_pfn(rmrru->end_address));
> > +                overlap = 1;
> > +                break;
> > +            }
> > +        }
> > +        /* Don't add overlapping RMRR. */
> > +        if ( overlap )
> > +            continue;
> > +
> > +        pfn = extra_rmrr_units[i].base_pfn;
> > +        do
> > +        {
> > +            if ( !mfn_valid(pfn) )
> > +            {
> > +                printk(XENLOG_ERR VTDPREFIX
> > +                       "Invalid pfn in RMRR range "ERMRRU_FMT"\n",
> > +                       ERMRRU_ARG(extra_rmrr_units[i]));
> > +                break;
> > +            }
> > +        } while ( pfn++ < extra_rmrr_units[i].end_pfn );
> > +
> > +        /* Invalid pfn in range as the loop ended before end_pfn was 
> > reached. */
> > +        if ( pfn <= extra_rmrr_units[i].end_pfn )
> > +            continue;
> > +
> > +        acpi_rmrr = xzalloc(struct acpi_rmrr_unit);
> > +        if ( !acpi_rmrr )
> > +            return;
> > +
> > +        acpi_rmrr->scope.devices = xmalloc_array(u16,
> > +                                                 
> > extra_rmrr_units[i].dev_count);
> > +        if ( !acpi_rmrr->scope.devices )
> > +        {
> > +            xfree(acpi_rmrr);
> > +            return;
> > +        }
> > +
> > +        seg = 0;
> > +        for ( dev = 0; dev < extra_rmrr_units[i].dev_count; dev++ )
> > +        {
> > +            acpi_rmrr->scope.devices[dev] = extra_rmrr_units[i].sbdf[dev];
> > +            seg = seg | PCI_SEG(extra_rmrr_units[i].sbdf[dev]);
> 
> Once again - |= please.
> 

Missed this one.

> > +        }
> > +        if ( seg != PCI_SEG(extra_rmrr_units[i].sbdf[0]) )
> > +        {
> > +            printk(XENLOG_ERR VTDPREFIX
> > +                   "Segments are not equal for RMRR range "ERMRRU_FMT"\n",
> > +                   ERMRRU_ARG(extra_rmrr_units[i]));
> > +            scope_devices_free(&acpi_rmrr->scope);
> > +            xfree(acpi_rmrr);
> > +            continue;
> > +        }
> > +
> > +        acpi_rmrr->segment = seg;
> > +        acpi_rmrr->base_address = 
> > pfn_to_paddr(extra_rmrr_units[i].base_pfn);
> > +        acpi_rmrr->end_address = pfn_to_paddr(extra_rmrr_units[i].end_pfn 
> > + 1);
> 
> And this seems wrong too, unless I'm mistaken with the inclusive-ness.
>
The end_address is exclusive, see above.

> Jan
> 

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