commit a0044755679f3e761b8b95995e5f2db2b7efd0f6
author Gleb Natapov <gleb@redhat.com> Wed Feb 10 14:21:31 2010 +0200
committer Marcelo Tosatti <mtosatti@redhat.com> Mon Mar 01 12:36:11 2010 -0300
tree 3a4db9d3e0512109130c2f4f1f425305378c0a27
parent 60a29d4ea4e7b6b95d9391ebc8625b0426f3a363

KVM: x86 emulator: Add Virtual-8086 mode of emulation

For some instructions CPU behaves differently for real-mode and
virtual 8086. Let emulator know which mode cpu is in, so it will
not poke into vcpu state directly.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/x86/include/asm/kvm_emulate.h

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index 9b697c2..784d7c5 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -168,6 +168,7 @@
 
 /* Execution mode, passed to the emulator. */
 #define X86EMUL_MODE_REAL     0	/* Real mode.             */
+#define X86EMUL_MODE_VM86     1	/* Virtual 8086 mode.     */
 #define X86EMUL_MODE_PROT16   2	/* 16-bit protected mode. */
 #define X86EMUL_MODE_PROT32   4	/* 32-bit protected mode. */
 #define X86EMUL_MODE_PROT64   8	/* 64-bit (long) mode.    */

arch/x86/kvm/emulate.c

diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 45a4f7c..e4e2df3 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -899,6 +899,7 @@
 
 	switch (mode) {
 	case X86EMUL_MODE_REAL:
+	case X86EMUL_MODE_VM86:
 	case X86EMUL_MODE_PROT16:
 		def_op_bytes = def_ad_bytes = 2;
 		break;
@@ -1525,7 +1526,7 @@
 
 	/* syscall is not available in real mode */
 	if (c->lock_prefix || ctxt->mode == X86EMUL_MODE_REAL
-	    || !is_protmode(ctxt->vcpu))
+	    || ctxt->mode == X86EMUL_MODE_VM86)
 		return -1;
 
 	setup_syscalls_segments(ctxt, &cs, &ss);
@@ -1577,8 +1578,8 @@
 	if (c->lock_prefix)
 		return -1;
 
-	/* inject #GP if in real mode or paging is disabled */
-	if (ctxt->mode == X86EMUL_MODE_REAL || !is_protmode(ctxt->vcpu)) {
+	/* inject #GP if in real mode */
+	if (ctxt->mode == X86EMUL_MODE_REAL) {
 		kvm_inject_gp(ctxt->vcpu, 0);
 		return -1;
 	}
@@ -1642,8 +1643,9 @@
 	if (c->lock_prefix)
 		return -1;
 
-	/* inject #GP if in real mode or paging is disabled */
-	if (ctxt->mode == X86EMUL_MODE_REAL || !is_protmode(ctxt->vcpu)) {
+	/* inject #GP if in real mode or Virtual 8086 mode */
+	if (ctxt->mode == X86EMUL_MODE_REAL ||
+	    ctxt->mode == X86EMUL_MODE_VM86) {
 		kvm_inject_gp(ctxt->vcpu, 0);
 		return -1;
 	}

arch/x86/kvm/x86.c

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b2f91b9..a283795 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3348,8 +3348,9 @@
 		vcpu->arch.emulate_ctxt.vcpu = vcpu;
 		vcpu->arch.emulate_ctxt.eflags = kvm_get_rflags(vcpu);
 		vcpu->arch.emulate_ctxt.mode =
+			(!is_protmode(vcpu)) ? X86EMUL_MODE_REAL :
 			(vcpu->arch.emulate_ctxt.eflags & X86_EFLAGS_VM)
-			? X86EMUL_MODE_REAL : cs_l
+			? X86EMUL_MODE_VM86 : cs_l
 			? X86EMUL_MODE_PROT64 :	cs_db
 			? X86EMUL_MODE_PROT32 : X86EMUL_MODE_PROT16;