Changeset 96882 in vbox

Timestamp:

Sep 26, 2022 6:56:21 PM (2 years ago)

Author:

vboxsync

Message:

IEM: Only zap the high half of 64-bit destination register actually used by CMPXCHG, not both possible registers.

File:

• trunk/src/VBox/VMM/VMMAll/IEMAllInstructionsTwoByte0f.cpp.h (modified) (1 diff)

trunk/src/VBox/VMM/VMMAll/IEMAllInstructionsTwoByte0f.cpp.h

@@ -9769 +9769 @@
                     IEM_MC_CALL_VOID_AIMPL_4(iemAImpl_cmpxchg_u32_locked, pu32Dst, pu32Eax, u32Src, pEFlags);
 
-                IEM_MC_CLEAR_HIGH_GREG_U64_BY_REF(pu32Eax);
-                IEM_MC_CLEAR_HIGH_GREG_U64_BY_REF(pu32Dst);
+                IEM_MC_IF_EFL_BIT_SET(X86_EFL_ZF) {
+                    IEM_MC_CLEAR_HIGH_GREG_U64_BY_REF(pu32Dst);
+                } IEM_MC_ELSE() {
+                    IEM_MC_CLEAR_HIGH_GREG_U64_BY_REF(pu32Eax);
+                } IEM_MC_ENDIF();
+
                 IEM_MC_ADVANCE_RIP();
                 IEM_MC_END();