[PATCH kvm-unit-tests 2/2] nSVM: Test MBZ bits in nested CR3 (nCR3)

[Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>]

According to section "Nested Paging and VMRUN/#VMEXIT" in APM vol 2, the
following guest state is illegal:

            "Any MBZ bit of nCR3 is set"

Signed-off-by: Krish Sadhukhan <krish.sadhkhan@xxxxxxxxxx>
---
 x86/svm_tests.c | 41 ++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/x86/svm_tests.c b/x86/svm_tests.c
index 8ad6122..ecfb5cb 100644
--- a/x86/svm_tests.c
+++ b/x86/svm_tests.c
@@ -2183,7 +2183,10 @@ static void basic_guest_main(struct svm_test *test)
 			vmcb->save.cr0 = tmp;				\
 			break;						\
 		case 3:							\
-			vmcb->save.cr3 = tmp;				\
+			if (strcmp(test_name, "nested ") == 0)		\
+				vmcb->control.nested_cr3 = tmp;		\
+			else						\
+				vmcb->save.cr3 = tmp;			\
 			break;						\
 		case 4:							\
 			vmcb->save.cr4 = tmp;				\
@@ -2547,6 +2550,41 @@ static void guest_rflags_test_db_handler(struct ex_regs *r)
 	r->rflags &= ~X86_EFLAGS_TF;
 }
 
+static void test_ncr3(void)
+{
+	u64 ncr3_saved = vmcb->control.nested_cr3;
+	u64 nested_ctl_saved = vmcb->control.nested_ctl;
+	u32 ret;
+
+	if (!npt_supported()) {
+		report_skip("NPT not supported");
+		return;
+	}
+
+	vmcb->control.nested_ctl = 0;
+	SVM_TEST_CR_RESERVED_BITS(0, 63, 1, 3, ncr3_saved,
+	    SVM_CR3_LONG_MBZ_MASK, SVM_EXIT_VMMCALL, "nested ");
+
+	vmcb->control.nested_cr3 = ncr3_saved & ~SVM_CR3_LONG_MBZ_MASK;
+	ret = svm_vmrun();
+	report (ret == SVM_EXIT_VMMCALL, "Test CR3 nested 63:0: %lx, wanted "
+	    "exit 0x%x, got 0x%x", ncr3_saved & ~SVM_CR3_LONG_MBZ_MASK,
+	    SVM_EXIT_VMMCALL, ret);
+
+	vmcb->control.nested_ctl = 1;
+	SVM_TEST_CR_RESERVED_BITS(0, 63, 1, 3, ncr3_saved,
+	    SVM_CR3_LONG_MBZ_MASK, SVM_EXIT_ERR, "nested ");
+
+	vmcb->control.nested_cr3 = ncr3_saved & ~SVM_CR3_LONG_MBZ_MASK;
+	ret = svm_vmrun();
+	report (ret == SVM_EXIT_VMMCALL, "Test CR3 nested 63:0: %lx, wanted "
+	    "exit 0x%x, got 0x%x", ncr3_saved & ~SVM_CR3_LONG_MBZ_MASK,
+	    SVM_EXIT_VMMCALL, ret);
+
+	vmcb->control.nested_cr3 = ncr3_saved;
+	vmcb->control.nested_ctl = nested_ctl_saved;
+}
+
 static void svm_guest_state_test(void)
 {
 	test_set_guest(basic_guest_main);
@@ -2557,6 +2595,7 @@ static void svm_guest_state_test(void)
 	test_dr();
 	test_msrpm_iopm_bitmap_addrs();
 	test_canonicalization();
+	test_ncr3();
 }
 
 extern void guest_rflags_test_guest(struct svm_test *test);
-- 
2.27.0