KVM: x86 emulator: Add flag to check for protected mode instructions

This patch adds a flag for the opcoded to tag instruction
which are only recognized in protected mode. The necessary
check is added too.

Signed-off-by: Joerg Roedel <[email protected]>
Signed-off-by: Avi Kivity <[email protected]>

Author: joergroedel

arch/x86/include/asm/kvm_emulate.h

@@ -274,6 +274,10 @@ struct x86_emulate_ctxt {
 #define X86EMUL_MODE_PROT32   4	/* 32-bit protected mode. */
 #define X86EMUL_MODE_PROT64   8	/* 64-bit (long) mode.    */
 
+/* any protected mode   */
+#define X86EMUL_MODE_PROT     (X86EMUL_MODE_PROT16|X86EMUL_MODE_PROT32| \
+			       X86EMUL_MODE_PROT64)
+
 enum x86_intercept_stage {
 	X86_ICPT_PRE_EXCEPT,
 	X86_ICPT_POST_EXCEPT,

arch/x86/kvm/emulate.c

@@ -78,6 +78,7 @@
 #define Prefix      (1<<16)     /* Instruction varies with 66/f2/f3 prefix */
 #define Sse         (1<<17)     /* SSE Vector instruction */
 /* Misc flags */
+#define Prot        (1<<21) /* instruction generates #UD if not in prot-mode */
 #define VendorSpecific (1<<22) /* Vendor specific instruction */
 #define NoAccess    (1<<23) /* Don't access memory (lea/invlpg/verr etc) */
 #define Op3264      (1<<24) /* Operand is 64b in long mode, 32b otherwise */
@@ -3143,6 +3144,12 @@ x86_emulate_insn(struct x86_emulate_ctxt *ctxt)
 		goto done;
 	}
 
+	/* Instruction can only be executed in protected mode */
+	if ((c->d & Prot) && !(ctxt->mode & X86EMUL_MODE_PROT)) {
+		rc = emulate_ud(ctxt);
+		goto done;
+	}
+
 	/* Do instruction specific permission checks */
 	if (c->check_perm) {
 		rc = c->check_perm(ctxt);