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

[patchbot@xxxxxxx]

commit 55f8c389d4348cc517946fdcb10794112458e81e
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri Jul 24 10:17:26 2020 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri Jul 24 10:17:26 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>
---
 xen/arch/x86/acpi/wakeup_prot.S | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/xen/arch/x86/acpi/wakeup_prot.S b/xen/arch/x86/acpi/wakeup_prot.S
index dcc7e2327d..a2c41c4f3f 100644
--- a/xen/arch/x86/acpi/wakeup_prot.S
+++ b/xen/arch/x86/acpi/wakeup_prot.S
@@ -49,6 +49,10 @@ ENTRY(s3_resume)
         mov     %rax, %cr0
 
         mov     $__HYPERVISOR_DS64, %eax
+        mov     %eax, %ds
+        mov     %eax, %es
+        mov     %eax, %fs
+        mov     %eax, %gs
         mov     %eax, %ss
         mov     saved_rsp(%rip), %rsp
 
--
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