From d0e4f15cfdad64de400ab32ab544f5434b38c9f7 Mon Sep 17 00:00:00 2001
From: Keir Fraser <keir@xensource.com>
Date: Mon, 2 Jul 2007 00:24:59 +0100
Subject: [PATCH] Use 32bit operand and address during VMXAssist protected to
 real. Signed-off-by: Xin Li <xin.b.li@intel.com>

---
 tools/firmware/vmxassist/setup.c |  3 +-
 tools/firmware/vmxassist/vm86.c  | 61 ++++++++++++++++++++++++++------
 2 files changed, 52 insertions(+), 12 deletions(-)

diff --git a/tools/firmware/vmxassist/setup.c b/tools/firmware/vmxassist/setup.c
index fd03e3c6cb..1e2e86c27b 100644
--- a/tools/firmware/vmxassist/setup.c
+++ b/tools/firmware/vmxassist/setup.c
@@ -198,9 +198,10 @@ enter_real_mode(struct regs *regs)
 	}
 
 	/* go from protected to real mode */
-	regs->eflags |= EFLAGS_VM;
 	set_mode(regs, VM86_PROTECTED_TO_REAL);
 	emulate(regs);
+	if (mode != VM86_REAL)
+		panic("failed to emulate between clear PE and long jump.\n");
 }
 
 /*
diff --git a/tools/firmware/vmxassist/vm86.c b/tools/firmware/vmxassist/vm86.c
index 357a73e353..847b625e07 100644
--- a/tools/firmware/vmxassist/vm86.c
+++ b/tools/firmware/vmxassist/vm86.c
@@ -580,8 +580,13 @@ movr(struct regs *regs, unsigned prefix, unsigned opc)
 	unsigned addr = operand(prefix, regs, modrm);
 	unsigned val, r = (modrm >> 3) & 7;
 
-	if ((modrm & 0xC0) == 0xC0) /* no registers */
-		return 0;
+	if ((modrm & 0xC0) == 0xC0) {
+		/*
+		 * Emulate all guest instructions in protected to real mode.
+		 */
+		if (mode != VM86_PROTECTED_TO_REAL)
+			return 0;
+	}
 
 	switch (opc) {
 	case 0x88: /* addr32 mov r8, r/m8 */
@@ -806,8 +811,13 @@ mov_to_seg(struct regs *regs, unsigned prefix, unsigned opc)
 {
 	unsigned modrm = fetch8(regs);
 
-	/* Only need to emulate segment loads in real->protected mode. */
-	if (mode != VM86_REAL_TO_PROTECTED)
+	/*
+	 * Emulate segment loads in:
+	 * 1) real->protected mode.
+	 * 2) protected->real mode.
+	 */
+	if ((mode != VM86_REAL_TO_PROTECTED) &&
+	    (mode != VM86_PROTECTED_TO_REAL))
 		return 0;
 
 	/* Register source only. */
@@ -817,6 +827,8 @@ mov_to_seg(struct regs *regs, unsigned prefix, unsigned opc)
 	switch ((modrm & 0x38) >> 3) {
 	case 0: /* es */
 		regs->ves = getreg16(regs, modrm);
+		if (mode == VM86_PROTECTED_TO_REAL)
+			return 1;
 		saved_rm_regs.ves = 0;
 		oldctx.es_sel = regs->ves;
 		return 1;
@@ -825,21 +837,29 @@ mov_to_seg(struct regs *regs, unsigned prefix, unsigned opc)
 
 	case 2: /* ss */
 		regs->uss = getreg16(regs, modrm);
+		if (mode == VM86_PROTECTED_TO_REAL)
+			return 1;
 		saved_rm_regs.uss = 0;
 		oldctx.ss_sel = regs->uss;
 		return 1;
 	case 3: /* ds */
 		regs->vds = getreg16(regs, modrm);
+		if (mode == VM86_PROTECTED_TO_REAL)
+			return 1;
 		saved_rm_regs.vds = 0;
 		oldctx.ds_sel = regs->vds;
 		return 1;
 	case 4: /* fs */
 		regs->vfs = getreg16(regs, modrm);
+		if (mode == VM86_PROTECTED_TO_REAL)
+			return 1;
 		saved_rm_regs.vfs = 0;
 		oldctx.fs_sel = regs->vfs;
 		return 1;
 	case 5: /* gs */
 		regs->vgs = getreg16(regs, modrm);
+		if (mode == VM86_PROTECTED_TO_REAL)
+			return 1;
 		saved_rm_regs.vgs = 0;
 		oldctx.gs_sel = regs->vgs;
 		return 1;
@@ -1055,7 +1075,8 @@ set_mode(struct regs *regs, enum vm86_mode newmode)
 	}
 
 	mode = newmode;
-	TRACE((regs, 0, states[mode]));
+	if (mode != VM86_PROTECTED)
+		TRACE((regs, 0, states[mode]));
 }
 
 static void
@@ -1269,6 +1290,12 @@ opcode(struct regs *regs)
 	unsigned opc, modrm, disp;
 	unsigned prefix = 0;
 
+	if (mode == VM86_PROTECTED_TO_REAL &&
+		oldctx.cs_arbytes.fields.default_ops_size) {
+		prefix |= DATA32;
+		prefix |= ADDR32;
+	}
+
 	for (;;) {
 		switch ((opc = fetch8(regs))) {
 		case 0x07: /* pop %es */
@@ -1379,17 +1406,29 @@ opcode(struct regs *regs)
 			continue;
 
 		case 0x66:
-			TRACE((regs, regs->eip - eip, "data32"));
-			prefix |= DATA32;
+			if (mode == VM86_PROTECTED_TO_REAL &&
+				oldctx.cs_arbytes.fields.default_ops_size) {
+				TRACE((regs, regs->eip - eip, "data16"));
+				prefix &= ~DATA32;
+			} else {
+				TRACE((regs, regs->eip - eip, "data32"));
+				prefix |= DATA32;
+			}
 			continue;
 
 		case 0x67:
-			TRACE((regs, regs->eip - eip, "addr32"));
-			prefix |= ADDR32;
+			if (mode == VM86_PROTECTED_TO_REAL &&
+				oldctx.cs_arbytes.fields.default_ops_size) {
+				TRACE((regs, regs->eip - eip, "addr16"));
+				prefix &= ~ADDR32;
+			} else {
+				TRACE((regs, regs->eip - eip, "addr32"));
+				prefix |= ADDR32;
+			}
 			continue;
 
-		case 0x88: /* addr32 mov r8, r/m8 */
-		case 0x8A: /* addr32 mov r/m8, r8 */
+		case 0x88: /* mov r8, r/m8 */
+		case 0x8A: /* mov r/m8, r8 */
 			if (mode != VM86_REAL && mode != VM86_REAL_TO_PROTECTED)
 				goto invalid;
 			if ((prefix & ADDR32) == 0)
-- 
2.30.2