x86emul: SYSRET must change CPL

The special AMD behavior of leaving SS mostly alone wasn't really
complete: We need to adjust CPL aka SS.DPL.

Signed-off-by: Jan Beulich <jbeulich@suse.com>

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c b/xen/arch/x86/x86_emulate/x86_emulate.c
index 3ed64c13ea85f093c45b7ff6c297f421e4fbb5a6..1959fc227a708cf8b0fe58e848ed008fc5dd6e2b 100644 (file)
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -6022,6 +6022,8 @@ x86_emulate(
 
             /* There's explicitly no RPL adjustment here. */
             sreg.sel = (msr_val >> 48) + 8;
+            /* But DPL needs adjustment, for the new CPL to be correct. */
+            sreg.dpl = 3;
         }
 
 #ifdef __x86_64__