On 21.05.2021 15:12, Boris Ostrovsky wrote: > > On 5/21/21 3:45 AM, Juergen Gross wrote: >> On 21.05.21 09:26, Jan Beulich wrote: >>> On 21.05.2021 09:18, Juergen Gross wrote: >>>> On 20.05.21 14:08, Jan Beulich wrote: >>>>> On 20.05.2021 13:57, Juergen Gross wrote: >>>>>> On 20.05.21 13:42, Jan Beulich wrote: >>>>>>> xen_setup_gdt(), via xen_load_gdt_boot(), wants to adjust page tables. >>>>>>> For this to work when NX is not available, x86_configure_nx() needs >> to >>>>>>> be called first. >>>>>>> >>>>>>> Reported-by: Olaf Hering <o...@aepfle.de> >>>>>>> Signed-off-by: Jan Beulich <jbeul...@suse.com> >>>>>> >>>>>> Reviewed-by: Juergen Gross <jgr...@suse.com> >>>>> >>>>> Thanks. I guess I forgot >>>>> >>>>> Cc: sta...@vger.kernel.org >>>>> >>>>> If you agree, can you please add this before pushing to Linus? >>>> >>>> Uh, just had a look why x86_configure_nx() was called after >>>> xen_setup_gdt(). >>>> >>>> Upstream your patch will be fine, but before kernel 5.9 it will >>>> break running as 32-bit PV guest (see commit 36104cb9012a82e7). >>> >>> Oh, indeed. That commit then actually introduced the issue here, >>> and hence a Fixes: tag may be warranted. >> >> Added it already. :-) >> >> And I've limited the backport to happen not for 5.8 and older, of >> course. > > > Did something changed recently that this became a problem? That commit has > been there for 3 years.
He happened to try on a system where NX was turned off in the BIOS. That's not a setting you would usually find in use. > Didn't Olaf report this to be a problem only on SLES kernels? Which I assume have backports of the problematic change. Jan
