diff mbox series

[kvm-unit-tests,1/2] x86: nVMX: Add some corner-case VMX-preemption timer tests

Message ID 20200414001026.50051-1-jmattson@google.com (mailing list archive)
State New, archived
Headers show
Series [kvm-unit-tests,1/2] x86: nVMX: Add some corner-case VMX-preemption timer tests | expand

Commit Message

Jim Mattson April 14, 2020, 12:10 a.m. UTC 
Verify that both injected events and debug traps that result from
pending debug exceptions take precedence over a "VMX-preemption timer
expired" VM-exit resulting from a zero-valued VMX-preemption timer.

Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Oliver Upton <oupton@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
---
 x86/vmx_tests.c | 120 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)

Comments

Jim Mattson April 22, 2020, 4:26 p.m. UTC | #1 
On Mon, Apr 13, 2020 at 5:10 PM Jim Mattson <jmattson@google.com> wrote:
>
> Verify that both injected events and debug traps that result from
> pending debug exceptions take precedence over a "VMX-preemption timer
> expired" VM-exit resulting from a zero-valued VMX-preemption timer.
>
> Signed-off-by: Jim Mattson <jmattson@google.com>
> Reviewed-by: Oliver Upton <oupton@google.com>
> Reviewed-by: Peter Shier <pshier@google.com>
> ---
>  x86/vmx_tests.c | 120 ++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 120 insertions(+)
>
> diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
> index 1f97fe3..fccb27f 100644
> --- a/x86/vmx_tests.c
> +++ b/x86/vmx_tests.c
> @@ -8319,6 +8319,125 @@ static void vmx_store_tsc_test(void)
>                msr_entry.value, low, high);
>  }
>
> +static void vmx_preemption_timer_zero_test_db_handler(struct ex_regs *regs)
> +{
> +}
> +
> +static void vmx_preemption_timer_zero_test_guest(void)
> +{
> +       while (vmx_get_test_stage() < 3)
> +               vmcall();
> +}
> +
> +static void vmx_preemption_timer_zero_activate_preemption_timer(void)
> +{
> +       vmcs_set_bits(PIN_CONTROLS, PIN_PREEMPT);
> +       vmcs_write(PREEMPT_TIMER_VALUE, 0);
> +}
> +
> +static void vmx_preemption_timer_zero_advance_past_vmcall(void)
> +{
> +       vmcs_clear_bits(PIN_CONTROLS, PIN_PREEMPT);
> +       enter_guest();
> +       skip_exit_vmcall();
> +}
> +
> +static void vmx_preemption_timer_zero_inject_db(bool intercept_db)
> +{
> +       vmx_preemption_timer_zero_activate_preemption_timer();
> +       vmcs_write(ENT_INTR_INFO, INTR_INFO_VALID_MASK |
> +                  INTR_TYPE_HARD_EXCEPTION | DB_VECTOR);
> +       vmcs_write(EXC_BITMAP, intercept_db ? 1 << DB_VECTOR : 0);
> +       enter_guest();
> +}
> +
> +static void vmx_preemption_timer_zero_set_pending_dbg(u32 exception_bitmap)
> +{
> +       vmx_preemption_timer_zero_activate_preemption_timer();
> +       vmcs_write(GUEST_PENDING_DEBUG, BIT(12) | DR_TRAP1);
> +       vmcs_write(EXC_BITMAP, exception_bitmap);
> +       enter_guest();
> +}
> +
> +static void vmx_preemption_timer_zero_expect_preempt_at_rip(u64 expected_rip)
> +{
> +       u32 reason = (u32)vmcs_read(EXI_REASON);
> +       u64 guest_rip = vmcs_read(GUEST_RIP);
> +
> +       report(reason == VMX_PREEMPT && guest_rip == expected_rip,
> +              "Exit reason is 0x%x (expected 0x%x) and guest RIP is %lx (0x%lx expected).",
> +              reason, VMX_PREEMPT, guest_rip, expected_rip);
> +}
> +
> +/*
> + * This test ensures that when the VMX preemption timer is zero at
> + * VM-entry, a VM-exit occurs after any event injection and after any
> + * pending debug exceptions are raised, but before execution of any
> + * guest instructions.
> + */
> +static void vmx_preemption_timer_zero_test(void)
> +{
> +       u64 db_fault_address = (u64)get_idt_addr(&boot_idt[DB_VECTOR]);
> +       handler old_db;
> +       u32 reason;
> +
> +       if (!(ctrl_pin_rev.clr & PIN_PREEMPT)) {
> +               report_skip("'Activate VMX-preemption timer' not supported");
> +               return;
> +       }
> +
> +       /*
> +        * Install a custom #DB handler that doesn't abort.
> +        */
> +       old_db = handle_exception(DB_VECTOR,
> +                                 vmx_preemption_timer_zero_test_db_handler);
> +
> +       test_set_guest(vmx_preemption_timer_zero_test_guest);
> +
> +       /*
> +        * VMX-preemption timer should fire after event injection.
> +        */
> +       vmx_set_test_stage(0);
> +       vmx_preemption_timer_zero_inject_db(0);
> +       vmx_preemption_timer_zero_expect_preempt_at_rip(db_fault_address);
> +       vmx_preemption_timer_zero_advance_past_vmcall();
> +
> +       /*
> +        * VMX-preemption timer should fire after event injection.
> +        * Exception bitmap is irrelevant, since you can't intercept
> +        * an event that you injected.
> +        */
> +       vmx_set_test_stage(1);
> +       vmx_preemption_timer_zero_inject_db(1 << DB_VECTOR);
> +       vmx_preemption_timer_zero_expect_preempt_at_rip(db_fault_address);
> +       vmx_preemption_timer_zero_advance_past_vmcall();
> +
> +       /*
> +        * VMX-preemption timer should fire after pending debug exceptions
> +        * have delivered a #DB trap.
> +        */
> +       vmx_set_test_stage(2);
> +       vmx_preemption_timer_zero_set_pending_dbg(0);
> +       vmx_preemption_timer_zero_expect_preempt_at_rip(db_fault_address);
> +       vmx_preemption_timer_zero_advance_past_vmcall();
> +
> +       /*
> +        * VMX-preemption timer would fire after pending debug exceptions
> +        * have delivered a #DB trap, but in this case, the #DB trap is
> +        * intercepted.
> +        */
> +       vmx_set_test_stage(3);
> +       vmx_preemption_timer_zero_set_pending_dbg(1 << DB_VECTOR);
> +       reason = (u32)vmcs_read(EXI_REASON);
> +       report(reason == VMX_EXC_NMI, "Exit reason is 0x%x (expected 0x%x)",
> +              reason, VMX_EXC_NMI);
> +
> +       vmcs_clear_bits(PIN_CONTROLS, PIN_PREEMPT);
> +       enter_guest();
> +
> +       handle_exception(DB_VECTOR, old_db);
> +}
> +
>  static void vmx_db_test_guest(void)
>  {
>         /*
> @@ -9623,6 +9742,7 @@ struct vmx_test vmx_tests[] = {
>         TEST(vmx_pending_event_test),
>         TEST(vmx_pending_event_hlt_test),
>         TEST(vmx_store_tsc_test),
> +       TEST(vmx_preemption_timer_zero_test),
>         /* EPT access tests. */
>         TEST(ept_access_test_not_present),
>         TEST(ept_access_test_read_only),
> --
> 2.26.0.110.g2183baf09c-goog

Adding +Paolo Bonzini.
diff mbox series

Patch

diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index 1f97fe3..fccb27f 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -8319,6 +8319,125 @@  static void vmx_store_tsc_test(void)
 	       msr_entry.value, low, high);
 }
 
+static void vmx_preemption_timer_zero_test_db_handler(struct ex_regs *regs)
+{
+}
+
+static void vmx_preemption_timer_zero_test_guest(void)
+{
+	while (vmx_get_test_stage() < 3)
+		vmcall();
+}
+
+static void vmx_preemption_timer_zero_activate_preemption_timer(void)
+{
+	vmcs_set_bits(PIN_CONTROLS, PIN_PREEMPT);
+	vmcs_write(PREEMPT_TIMER_VALUE, 0);
+}
+
+static void vmx_preemption_timer_zero_advance_past_vmcall(void)
+{
+	vmcs_clear_bits(PIN_CONTROLS, PIN_PREEMPT);
+	enter_guest();
+	skip_exit_vmcall();
+}
+
+static void vmx_preemption_timer_zero_inject_db(bool intercept_db)
+{
+	vmx_preemption_timer_zero_activate_preemption_timer();
+	vmcs_write(ENT_INTR_INFO, INTR_INFO_VALID_MASK |
+		   INTR_TYPE_HARD_EXCEPTION | DB_VECTOR);
+	vmcs_write(EXC_BITMAP, intercept_db ? 1 << DB_VECTOR : 0);
+	enter_guest();
+}
+
+static void vmx_preemption_timer_zero_set_pending_dbg(u32 exception_bitmap)
+{
+	vmx_preemption_timer_zero_activate_preemption_timer();
+	vmcs_write(GUEST_PENDING_DEBUG, BIT(12) | DR_TRAP1);
+	vmcs_write(EXC_BITMAP, exception_bitmap);
+	enter_guest();
+}
+
+static void vmx_preemption_timer_zero_expect_preempt_at_rip(u64 expected_rip)
+{
+	u32 reason = (u32)vmcs_read(EXI_REASON);
+	u64 guest_rip = vmcs_read(GUEST_RIP);
+
+	report(reason == VMX_PREEMPT && guest_rip == expected_rip,
+	       "Exit reason is 0x%x (expected 0x%x) and guest RIP is %lx (0x%lx expected).",
+	       reason, VMX_PREEMPT, guest_rip, expected_rip);
+}
+
+/*
+ * This test ensures that when the VMX preemption timer is zero at
+ * VM-entry, a VM-exit occurs after any event injection and after any
+ * pending debug exceptions are raised, but before execution of any
+ * guest instructions.
+ */
+static void vmx_preemption_timer_zero_test(void)
+{
+	u64 db_fault_address = (u64)get_idt_addr(&boot_idt[DB_VECTOR]);
+	handler old_db;
+	u32 reason;
+
+	if (!(ctrl_pin_rev.clr & PIN_PREEMPT)) {
+		report_skip("'Activate VMX-preemption timer' not supported");
+		return;
+	}
+
+	/*
+	 * Install a custom #DB handler that doesn't abort.
+	 */
+	old_db = handle_exception(DB_VECTOR,
+				  vmx_preemption_timer_zero_test_db_handler);
+
+	test_set_guest(vmx_preemption_timer_zero_test_guest);
+
+	/*
+	 * VMX-preemption timer should fire after event injection.
+	 */
+	vmx_set_test_stage(0);
+	vmx_preemption_timer_zero_inject_db(0);
+	vmx_preemption_timer_zero_expect_preempt_at_rip(db_fault_address);
+	vmx_preemption_timer_zero_advance_past_vmcall();
+
+	/*
+	 * VMX-preemption timer should fire after event injection.
+	 * Exception bitmap is irrelevant, since you can't intercept
+	 * an event that you injected.
+	 */
+	vmx_set_test_stage(1);
+	vmx_preemption_timer_zero_inject_db(1 << DB_VECTOR);
+	vmx_preemption_timer_zero_expect_preempt_at_rip(db_fault_address);
+	vmx_preemption_timer_zero_advance_past_vmcall();
+
+	/*
+	 * VMX-preemption timer should fire after pending debug exceptions
+	 * have delivered a #DB trap.
+	 */
+	vmx_set_test_stage(2);
+	vmx_preemption_timer_zero_set_pending_dbg(0);
+	vmx_preemption_timer_zero_expect_preempt_at_rip(db_fault_address);
+	vmx_preemption_timer_zero_advance_past_vmcall();
+
+	/*
+	 * VMX-preemption timer would fire after pending debug exceptions
+	 * have delivered a #DB trap, but in this case, the #DB trap is
+	 * intercepted.
+	 */
+	vmx_set_test_stage(3);
+	vmx_preemption_timer_zero_set_pending_dbg(1 << DB_VECTOR);
+	reason = (u32)vmcs_read(EXI_REASON);
+	report(reason == VMX_EXC_NMI, "Exit reason is 0x%x (expected 0x%x)",
+	       reason, VMX_EXC_NMI);
+
+	vmcs_clear_bits(PIN_CONTROLS, PIN_PREEMPT);
+	enter_guest();
+
+	handle_exception(DB_VECTOR, old_db);
+}
+
 static void vmx_db_test_guest(void)
 {
 	/*
@@ -9623,6 +9742,7 @@  struct vmx_test vmx_tests[] = {
 	TEST(vmx_pending_event_test),
 	TEST(vmx_pending_event_hlt_test),
 	TEST(vmx_store_tsc_test),
+	TEST(vmx_preemption_timer_zero_test),
 	/* EPT access tests. */
 	TEST(ept_access_test_not_present),
 	TEST(ept_access_test_read_only),