From ea6a659adc14fac94fc6a2fce95b3ede32ef27ae Mon Sep 17 00:00:00 2001
From: Gabe Black <gabe.black@gmail.com>
Date: Sun, 23 Jan 2022 06:17:15 -0800
Subject: [PATCH] arch-x86: Detect when entering virtual 8086 mode.

If we're entering virtual 8086 mode, panic. Some aspects of that mode
may actually work, but since it's essentially untested, lets be extra
cautious.

Change-Id: I78bbfcb75db8370f4271c75caabc0ec53f75a884
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/55810
Reviewed-by: Matthew Poremba <matthew.poremba@amd.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
---
 src/arch/x86/isa.cc | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/arch/x86/isa.cc b/src/arch/x86/isa.cc
index 713346e618..f426137ec1 100644
--- a/src/arch/x86/isa.cc
+++ b/src/arch/x86/isa.cc
@@ -318,6 +318,12 @@ ISA::setMiscReg(int miscReg, RegVal val)
         break;
       case MISCREG_CR8:
         break;
+      case MISCREG_RFLAGS:
+        {
+            RFLAGS rflags = val;
+            panic_if(rflags.vm, "Virtual 8086 mode is not supported.");
+            break;
+        }
       case MISCREG_CS_ATTR:
         {
             SegAttr toggled = regVal[miscReg] ^ val;