[PATCH 2/2][kvm-unit-test] nVMX x86: Check VMX-preemption timer controls on vmentry of L2 guests

[Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>]

According to section "Checks on VMX Controls" in Intel SDM vol 3C, the
following check needs to be enforced on vmentry of L2 guests:

    If the "activate VMX-preemption timer" VM-execution control is 0, the
    the "save VMX-preemption timer value" VM-exit control must also be 0.

Signed-off-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
Reviewed-by: Mihai Carabas <mihai.carabas@xxxxxxxxxx>
---
 x86/vmx_tests.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index b105b23..7f49048 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -4721,6 +4721,55 @@ static void test_pml(void)
 	vmcs_write(CPU_EXEC_CTRL1, secondary_saved);
 }
 
+ /*
+ * If the "activate VMX-preemption timer" VM-execution control is 0, the
+ * the "save VMX-preemption timer value" VM-exit control must also be 0.
+ *
+ *  [Intel SDM]
+ */
+static void test_vmx_preemption_timer(void)
+{
+	u32 saved_pin = vmcs_read(PIN_CONTROLS);
+	u32 saved_exit = vmcs_read(EXI_CONTROLS);
+	u32 pin = saved_pin;
+	u32 exit = saved_exit;
+
+	if (!((ctrl_exit_rev.clr & EXI_SAVE_PREEMPT) ||
+	    (ctrl_pin_rev.clr & PIN_PREEMPT))) {
+		printf("\"Save-VMX-preemption-timer\" control and/or \"Enable-VMX-preemption-timer\" control is not supported\n");
+		return;
+	}
+
+	pin |= PIN_PREEMPT;
+	vmcs_write(PIN_CONTROLS, pin);
+	exit &= ~EXI_SAVE_PREEMPT;
+	vmcs_write(EXI_CONTROLS, exit);
+	report_prefix_pushf("enable-VMX-preemption-timer enabled, save-VMX-preemption-timer disabled");
+	test_vmx_controls(true, false);
+	report_prefix_pop();
+
+	exit |= EXI_SAVE_PREEMPT;
+	vmcs_write(EXI_CONTROLS, exit);
+	report_prefix_pushf("enable-VMX-preemption-timer enabled, save-VMX-preemption-timer enabled");
+	test_vmx_controls(true, false);
+	report_prefix_pop();
+
+	pin &= ~PIN_PREEMPT;
+	vmcs_write(PIN_CONTROLS, pin);
+	report_prefix_pushf("enable-VMX-preemption-timer disabled, save-VMX-preemption-timer enabled");
+	test_vmx_controls(false, false);
+	report_prefix_pop();
+
+	exit &= ~EXI_SAVE_PREEMPT;
+	vmcs_write(EXI_CONTROLS, exit);
+	report_prefix_pushf("enable-VMX-preemption-timer disabled, save-VMX-preemption-timer disabled");
+	test_vmx_controls(true, false);
+	report_prefix_pop();
+
+	vmcs_write(PIN_CONTROLS, saved_pin);
+	vmcs_write(EXI_CONTROLS, saved_exit);
+}
+
 /*
  * Check that the virtual CPU checks all of the VMX controls as
  * documented in the Intel SDM.
@@ -4747,6 +4796,7 @@ static void vmx_controls_test(void)
 	test_invalid_event_injection();
 	test_vpid();
 	test_eptp();
+	test_vmx_preemption_timer();
 }
 
 static bool valid_vmcs_for_vmentry(void)
-- 
2.9.5