The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ae897fda4f507e4b239f0bdfd578b3688ca96fb4 Mon Sep 17 00:00:00 2001

From: Jan Beulich jbeulich@suse.com Date: Thu, 20 May 2021 13:42:42 +0200 Subject: [PATCH] x86/Xen: swap NX determination and GDT setup on BSP

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 36104cb9012a82e73 ("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: 36104cb9012a82e73 ("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

Link: https://lore.kernel.org/r/12a866b0-9e89-59f7-ebeb-a2a6cec0987a@suse.com Signed-off-by: Juergen Gross jgross@suse.com

diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index 17503fed2017..e87699aa2dc8 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -1273,16 +1273,16 @@ asmlinkage __visible void __init xen_start_kernel(void) /* Get mfn list */ xen_build_dynamic_phys_to_machine();

+ /* Work out if we support NX */ + get_cpu_cap(&boot_cpu_data); + x86_configure_nx(); + /* * Set up kernel GDT and segment registers, mainly so that * -fstack-protector code can be executed. */ xen_setup_gdt(0);

- /* Work out if we support NX */ - get_cpu_cap(&boot_cpu_data); - x86_configure_nx(); - /* Determine virtual and physical address sizes */ get_cpu_address_sizes(&boot_cpu_data);