--- /sys/src/9/pc/fns.h
+++ /sys/src/9/pc/fns.h
@@ -158,7 +158,7 @@ void	putcr0(ulong);
 void	putcr3(ulong);
 void	putcr4(ulong);
 void*	rampage(void);
-void	rdmsr(int, vlong*);
+int	rdmsr(int, vlong*);
 void	realmode(Ureg*);
 void	screeninit(void);
 void	(*screenputs)(char*, int);
diff --git a/sys/src/9/pc/io.h b/sys/src/9/pc/io.h
index 0b85d09f9..35ff5fb60 100644
--- a/sys/src/9/pc/io.h
+++ b/sys/src/9/pc/io.h
@@ -10,6 +10,7 @@ enum {
 	VectorCNA	= 7,		/* coprocessor not available */
 	Vector2F	= 8,		/* double fault */
 	VectorCSO	= 9,		/* coprocessor segment overrun */
+	VectorGPF	= 13,		/* General protection fault */
 	VectorPF	= 14,		/* page fault */
 	Vector15	= 15,		/* reserved */
 	VectorCERR	= 16,		/* coprocessor error */
--- /sys/src/9/pc/l.s
+++ /sys/src/9/pc/l.s
@@ -673,11 +673,17 @@ TEXT lcycles(SB),1,$0
 
 TEXT rdmsr(SB), $0				/* model-specific register */
 	MOVL	index+0(FP), CX
+TEXT mayberdmsr(SB), $0
 	RDMSR
+_rdmsrret:
 	MOVL	vlong+4(FP), CX			/* &vlong */
 	MOVL	AX, 0(CX)			/* lo */
 	MOVL	DX, 4(CX)			/* hi */
 	RET
+TEXT rdmsrfail(SB), $0
+	MOVL	$0xffffffff, AX
+	MOVL	AX, DX
+	JMP		_rdmsrret
 	
 TEXT wrmsr(SB), $0
 	MOVL	index+0(FP), CX
--- /sys/src/9/pc/trap.c
+++ /sys/src/9/pc/trap.c
@@ -14,6 +14,7 @@ static int trapinited;
 void	noted(Ureg*, ulong);
 
 static void debugbpt(Ureg*, void*);
+static void faultgpf(Ureg*, void*);
 static void fault386(Ureg*, void*);
 static void doublefault(Ureg*, void*);
 static void unexpected(Ureg*, void*);
@@ -221,6 +222,7 @@ trapinit(void)
 	 */
 	trapenable(VectorBPT, debugbpt, 0, "debugpt");
 	trapenable(VectorPF, fault386, 0, "fault386");
+	trapenable(VectorGPF, faultgpf, 0, "faultgpf");
 	trapenable(Vector2F, doublefault, 0, "doublefault");
 	trapenable(Vector15, unexpected, 0, "unexpected");
 	nmienable();
@@ -608,6 +610,17 @@ unexpected(Ureg* ureg, void*)
 
 extern void checkpages(void);
 extern void checkfault(ulong, ulong);
+extern void mayberdmsr(void);
+extern void rdmsrfail(void);
+
+static void
+faultgpf(Ureg* ureg, void*)
+{
+	if(ureg->pc != (ulong)mayberdmsr)
+		panic("unhandled GPF at 0x%.8lux", ureg->pc);
+	ureg->pc = (ulong)rdmsrfail;
+}
+
 static void
 fault386(Ureg* ureg, void*)
 {