Re: [Xen-devel] [PATCH v3] x86/dom0: improve PVH initrd and metadata placement

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

On Wed, Mar 04, 2020 at 11:31:23AM +0100, Jan Beulich wrote:
> On 04.03.2020 11:25, Roger Pau Monne wrote:
> > Don't assume there's going to be enough space at the tail of the
> > loaded kernel and instead try to find a suitable memory area where the
> > initrd and metadata can be loaded.
> > 
> > Reported-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> > Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> 
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> preferably with, as Andrew suggested, ...
> 
> > --- a/xen/arch/x86/hvm/dom0_build.c
> > +++ b/xen/arch/x86/hvm/dom0_build.c
> > @@ -490,6 +490,45 @@ static int __init pvh_populate_p2m(struct domain *d)
> >  #undef MB1_PAGES
> >  }
> >  
> > +static paddr_t find_memory(const struct domain *d, const struct elf_binary 
> > *elf,
> > +                           size_t size)
> > +{
> > +    paddr_t kernel_start = (paddr_t)elf->dest_base & PAGE_MASK;
> > +    paddr_t kernel_end = ROUNDUP((paddr_t)elf->dest_base + elf->dest_size,
> > +                                 PAGE_SIZE);
> > +    unsigned int i;
> > +
> > +    /*
> > +     * The memory map is sorted and all RAM regions starts and sizes are
> > +     * aligned to page boundaries.
> > +     */
> > +    for ( i = 0; i < d->arch.nr_e820; i++ )
> > +    {
> > +        paddr_t start, end = d->arch.e820[i].addr + d->arch.e820[i].size;
> > +
> > +        /* Don't use memory below 1MB, as it could overwrite the BDA/EBDA. 
> > */
> 
> ... IBFT added here (I'm not worried so much about whether BDA remains
> here or gets dropped). This could of course be done while committing.

Sure, thanks.

Roger.

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