[Xen-changelog] [xen master] x86emul: check for CMPXCHG8B availability

[patchbot@xxxxxxx]

commit bfe67e80b2dabb29e0b40d89d91023f0d75934be
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Dec 20 09:51:08 2016 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Dec 20 09:51:08 2016 +0100

    x86emul: check for CMPXCHG8B availability
    
    We can't exclude someone wanting to hide the instruction from guests.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/x86_emulate/x86_emulate.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c 
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 165eebb..be6904f 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -1290,6 +1290,7 @@ static bool vcpu_has(
 
 #define vcpu_has_fpu()         vcpu_has(         1, EDX,  0, ctxt, ops)
 #define vcpu_has_sep()         vcpu_has(         1, EDX, 11, ctxt, ops)
+#define vcpu_has_cx8()         vcpu_has(         1, EDX,  8, ctxt, ops)
 #define vcpu_has_cmov()        vcpu_has(         1, EDX, 15, ctxt, ops)
 #define vcpu_has_clflush()     vcpu_has(         1, EDX, 19, ctxt, ops)
 #define vcpu_has_mmx()         vcpu_has(         1, EDX, 23, ctxt, ops)
@@ -5427,7 +5428,10 @@ x86_emulate(
             op_bytes = 16;
         }
         else
+        {
+            vcpu_must_have(cx8);
             op_bytes = 8;
+        }
 
         old = container_of(&mmvalp->ymm[0], typeof(*old), u64[0]);
         aux = container_of(&mmvalp->ymm[2], typeof(*aux), u64[0]);
--
generated by git-patchbot for /home/xen/git/xen.git#master

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