x86/S3: put data segment registers into known state upon resume

wakeup_32 sets %ds and %es to BOOT_DS, while leaving %fs at what
wakeup_start did set it to, and %gs at whatever BIOS did load into it.
All of this may end up confusing the first load_segments() to run on
the BSP after resume, in particular allowing a non-nul selector value
to be left in %fs.

Alongside %ss, also put all other data segment registers into the same
state that the boot and CPU bringup paths put them in.

Reported-by: M. Vefa Bicakci <m.v.b@runbox.com>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 55f8c389d4348cc517946fdcb10794112458e81e
master date: 2020-07-24 10:17:26 +0200

diff --git a/xen/arch/x86/acpi/wakeup_prot.S b/xen/arch/x86/acpi/wakeup_prot.S
index 361751d290c3e4a685a10bd52c7bf423fafd42fe..6dc9e2bd82d11d9115f091dd03b5391329105dcc 100644 (file)
--- a/xen/arch/x86/acpi/wakeup_prot.S
+++ b/xen/arch/x86/acpi/wakeup_prot.S
@@ -84,6 +84,12 @@ ENTRY(__ret_point)
         mov     REF(saved_ss), %ss
         LOAD_GREG(sp)
 
+        mov     $__HYPERVISOR_DS64, %eax
+        mov     %eax, %ds
+        mov     %eax, %es
+        mov     %eax, %fs
+        mov     %eax, %gs
+
         /* Reload code selector */
         pushq   $(__HYPERVISOR_CS64)
         leaq    1f(%rip),%rax