[12/20] KVM: x86 emulator: Add Virtual-8086 mode of emulation

Commit Message

Avi Kivity Feb. 17, 2010, 1:45 p.m. UTC

None

Patch

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 @@  struct x86_emulate_ctxt {
 
 /* 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.    */
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 @@  x86_decode_insn(struct x86_emulate_ctxt *ctxt, struct x86_emulate_ops *ops)
 
 	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 @@  emulate_syscall(struct x86_emulate_ctxt *ctxt)
 
 	/* 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 @@  emulate_sysenter(struct x86_emulate_ctxt *ctxt)
 	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 @@  emulate_sysexit(struct x86_emulate_ctxt *ctxt)
 	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;
 	}
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 @@  int emulate_instruction(struct kvm_vcpu *vcpu,
 		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;