Re: [Xen-devel] [v10][PATCH 06/16] hvmloader/pci: Try to avoid placing BARs in RMRRs

["Chen, Tiejun" <tiejun.chen@xxxxxxxxx>]

> > > +/* Find the lowest RMRR higher than base. */
> > > +static int find_next_rmrr(uint32_t base)
> > > +{
> > > +    unsigned int i;
> > > +    int next_rmrr = -1;
> > > +    uint64_t min_base = (1ull << 32);
> > > +
> > > +    for ( i = 0; i < memory_map.nr_map ; i++ )
> > > +    {
> > > +        if ( memory_map.map[i].type == E820_RESERVED &&
> > > +             memory_map.map[i].addr > base &&
> > > +             memory_map.map[i].addr < min_base )
> > > +        {
> > > +            next_rmrr = i;
> > > +            min_base = memory_map.map[i].addr;
> > > +        }
> > > +    }
> > > +    return next_rmrr;
> > > +}
> > Considering _both_ callers, I think the function should actually return
> > the lowest RMRR higher than or equal to base.
> You mean instead of strictly greater than the base.
>
> > Or wait - we actually
> > need to find the lowest RMRR the _end_ of which is higher than base.
> Yes, you're right: there's always a risk that pci_mem_start will *start*
> in the middle of a range.  Looking for the next *end* is more robust.
Sorry this is not very clear to me so are you saying something like this?

    for ( i = 0; i < memory_map.nr_map ; i++ )
    {
        end = memory_map.map[i].addr + memory_map.map[i].size;

        if ( memory_map.map[i].type == E820_RESERVED &&
             end > base &&
             memory_map.map[i].addr < min_base )
        {
            next_rmrr = i;
            min_base = memory_map.map[i].addr;
        }
    }


Thanks
Tiejun

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