x86/Xen: swap NX determination and GDT setup on BSP

stable inclusion
from stable-5.10.40
commit e2c26ddd4e8565c54068d827da09bfabdf9d82de
bugzilla: 51882
CVE: NA

--------------------------------

commit ae897fda upstream.

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.

[jgross] Note that this is a revert of 36104cb9 ("x86/xen:
Delay get_cpu_cap until stack canary is established"), which is possible
now that we no longer support running as PV guest in 32-bit mode.

Cc: <stable.vger.kernel.org> # 5.9
Fixes: 36104cb9 ("x86/xen: Delay get_cpu_cap until stack canary is established")
Reported-by: Olaf Hering <olaf@aepfle.de>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Link: https://lore.kernel.org/r/12a866b0-9e89-59f7-ebeb-a2a6cec0987a@suse.com


Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Chen Jun <chenjun102@huawei.com>
Acked-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com>