On 30.11.2021 12:14, Andrew Cooper wrote:
> On 30/11/2021 10:33, Jan Beulich wrote:
>> On 30.11.2021 11:04, Andrew Cooper wrote:
>>> It has been 4 years since the default load address changed from 1M to 2M,
>>> and
>>> _stext ceased residing in l2_xenmap[0]. We should not be inserting an
>>> unused
>>> mapping.
>>>
>>> To ensure we don't create mappings accidentally, loop from 0 and obey
>>> _PAGE_PRESENT on all entries.
>>>
>>> Fixes: 7ed93f3a0dff ("x86: change default load address from 1 MiB to 2 MiB")
>>> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
>> Reviewed-by: Jan Beulich <jbeul...@suse.com>
>>
>> I guess this may be worth backporting despite not having any immediate
>> adverse effect.
>
> I'd say so, yes. I too can't see an adverse effect right now, but I'm
> definitely wary of stray executable mappings lying around.
>
>
> In principle, it would be nice to reclaim the 2M of space (which only
> exists for the MB1 path IIRC), but then we're getting into a position
> where xen_phys_start isn't really that any more.
Well, xen_phys_base might be slightly more accurate, but apart from that
I do think that we reclaim that space (as much as we did reclaim the 1Mb
before the change of the default load address):
if ( efi_boot_mem_unused(&eb_start, &eb_end) )
{
reserve_e820_ram(&boot_e820, __pa(_stext), __pa(eb_start));
reserve_e820_ram(&boot_e820, __pa(eb_end), __pa(__2M_rwdata_end));
}
else
reserve_e820_ram(&boot_e820, __pa(_stext), __pa(__2M_rwdata_end));
Jan
