[Xen-changelog] [xen master] x86/HVM: correct segment register loading during task switch

[patchbot@xxxxxxx]

commit bdb860d01cac7bcbaebbdce29ae9e9c7e9582d03
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon Sep 26 17:27:34 2016 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Sep 26 17:27:34 2016 +0200

    x86/HVM: correct segment register loading during task switch
    
    Instead of #NP, #SS needs to be raised for a non-present %ss
    descriptor.
    
    Don't lose the low two selector bits on null selector loads.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 7bad845..73730d1 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2723,6 +2723,7 @@ static int hvm_load_segment_selector(
         if ( (seg == x86_seg_cs) || (seg == x86_seg_ss) )
             goto fail;
         memset(&segr, 0, sizeof(segr));
+        segr.sel = sel;
         hvm_set_segment_register(v, seg, &segr);
         return 0;
     }
@@ -2749,7 +2750,8 @@ static int hvm_load_segment_selector(
         /* Segment present in memory? */
         if ( !(desc.b & _SEGMENT_P) )
         {
-            fault_type = TRAP_no_segment;
+            fault_type = (seg != x86_seg_ss) ? TRAP_no_segment
+                                             : TRAP_stack_error;
             goto unmap_and_fail;
         }
 
--
generated by git-patchbot for /home/xen/git/xen.git#master

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