[xen stable-4.12] x86/S3: put data segment registers into known state upon resume

[patchbot@xxxxxxx]

commit 85ce36d12b43ed15e556265c6204858d3b52d747
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Aug 7 17:31:16 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Aug 7 17:31:16 2020 +0200

    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@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    master commit: 55f8c389d4348cc517946fdcb10794112458e81e
    master date: 2020-07-24 10:17:26 +0200
---
 xen/arch/x86/acpi/wakeup_prot.S | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/xen/arch/x86/acpi/wakeup_prot.S b/xen/arch/x86/acpi/wakeup_prot.S
index 361751d290..6dc9e2bd82 100644
--- 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
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.12