From 6861fe80cfc486c492f7c5f03f397b0c8aaba69f Mon Sep 17 00:00:00 2001
From: Eduardo Habkost <ehabkost@redhat.com>
Date: Mon, 26 Feb 2018 03:58:08 -0500
Subject: [PATCH] target-i386: Add a marker to end of the region zeroed on
 reset

Instead of using cpuid_level, use an empty struct as a marker
(like we already did with {start,end}_init_save). This will avoid
accidentaly resetting the wrong fields if we change the field
ordering on CPUX86State.

Backports commit 5e992a8e337e710ea2d02f35668ac55a80e15f99 from qemu
---
 qemu/target-i386/cpu.c | 2 +-
 qemu/target-i386/cpu.h | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/qemu/target-i386/cpu.c b/qemu/target-i386/cpu.c
index 6632c0a4..7ef46033 100644
--- a/qemu/target-i386/cpu.c
+++ b/qemu/target-i386/cpu.c
@@ -2806,7 +2806,7 @@ static void x86_cpu_reset(CPUState *s)
 
     xcc->parent_reset(s);
 
-    memset(env, 0, offsetof(CPUX86State, cpuid_level));
+    memset(env, 0, offsetof(CPUX86State, end_reset_fields));
 
     tlb_flush(s, 1);
 
diff --git a/qemu/target-i386/cpu.h b/qemu/target-i386/cpu.h
index 9162d770..a644f05e 100644
--- a/qemu/target-i386/cpu.h
+++ b/qemu/target-i386/cpu.h
@@ -1101,6 +1101,7 @@ typedef struct CPUX86State {
     CPU_COMMON
 
     /* Fields from here on are preserved across CPU reset. */
+    struct {} end_reset_fields;
 
     /* processor features (e.g. for CPUID insn) */
     uint32_t cpuid_level;