Add a regression test for Linux commit afc8de0118be ("KVM: nVMX: Set
LDTR to its architecturally defined value on nested VM-Exit"). L1's
LDTR should be 0 after an emulated VM-exit from L2.
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
---
x86/vmx_tests.c | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
diff --git a/x86/vmx_tests.c b/x86/vmx_tests.c
index 3b97cfa6ed10..6093a90fd4ac 100644
--- a/x86/vmx_tests.c
+++ b/x86/vmx_tests.c
@@ -8363,6 +8363,44 @@ static void vmentry_movss_shadow_test(void)
vmcs_write(GUEST_RFLAGS, X86_EFLAGS_FIXED);
}
+static void vmx_ldtr_test_guest(void)
+{
+ u16 ldtr = sldt();
+
+ report(ldtr == NP_SEL, "Expected %x for L2 LDTR selector (got %x)",
+ NP_SEL, ldtr);
+}
+
+/*
+ * Ensure that the L1 LDTR is set to 0 on VM-exit.
+ */
+static void vmx_ldtr_test(void)
+{
+ const u8 ldt_ar = 0x82; /* Present LDT */
+ u16 sel = FIRST_SPARE_SEL;
+
+ /* Set up a non-zero L1 LDTR prior to VM-entry. */
+ set_gdt_entry(sel, 0, 0, ldt_ar, 0);
+ lldt(sel);
+
+ test_set_guest(vmx_ldtr_test_guest);
+ /*
+ * Set up a different LDTR for L2. The actual GDT contents are
+ * irrelevant, since we stuff the hidden descriptor state
+ * straight into the VMCS rather than reading it from the GDT.
+ */
+ vmcs_write(GUEST_SEL_LDTR, NP_SEL);
+ vmcs_write(GUEST_AR_LDTR, ldt_ar);
+ enter_guest();
+
+ /*
+ * VM-exit should clear LDTR (and make it unusable, but we
+ * won't verify that here).
+ */
+ sel = sldt();
+ report(!sel, "Expected 0 for L1 LDTR selector (got %x)", sel);
+}
+
static void vmx_single_vmcall_guest(void)
{
vmcall();
@@ -10724,6 +10762,7 @@ struct vmx_test vmx_tests[] = {
/* VMCS Shadowing tests */
TEST(vmx_vmcs_shadow_test),
/* Regression tests */
+ TEST(vmx_ldtr_test),
TEST(vmx_cr_load_test),
TEST(vmx_cr4_osxsave_test),
TEST(vmx_nm_test),
--
2.33.0.1079.g6e70778dc9-goog
