KVM: selftests: Provide valid inputs for MONITOR/MWAIT regs

Provide valid inputs for RAX, RCX, and RDX when testing whether or not
KVM injects a #UD on MONITOR/MWAIT.  SVM has a virtualization hole and
checks for _all_ faults before checking for intercepts, e.g. MONITOR with
an unsupported RCX will #GP before KVM gets a chance to intercept and
emulate.

Fixes: 2325d4dd73 ("KVM: selftests: Add MONITOR/MWAIT quirk test")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Link: https://lore.kernel.org/r/20220711225753.1073989-3-seanjc@google.com

tools/testing/selftests/kvm/x86_64/monitor_mwait_test.c

@@ -28,13 +28,17 @@ static void guest_monitor_wait(int testcase)
 
 	GUEST_SYNC(testcase);
 
-	vector = kvm_asm_safe("monitor");
+	/*
+	 * Arbitrarily MONITOR this function, SVM performs fault checks before
+	 * intercept checks, so the inputs for MONITOR and MWAIT must be valid.
+	 */
+	vector = kvm_asm_safe("monitor", "a"(guest_monitor_wait), "c"(0), "d"(0));
 	if (fault_wanted)
 		GUEST_ASSERT_2(vector == UD_VECTOR, testcase, vector);
 	else
 		GUEST_ASSERT_2(!vector, testcase, vector);
 
-	vector = kvm_asm_safe("mwait");
+	vector = kvm_asm_safe("mwait", "a"(guest_monitor_wait), "c"(0), "d"(0));
 	if (fault_wanted)
 		GUEST_ASSERT_2(vector == UD_VECTOR, testcase, vector);
 	else