[kvm-unit-tests,1/3] x86: nSVM: Check #NM exception handling in L2

Commit Message

Manali Shukla Dec. 29, 2021, 6:21 a.m. UTC

Add coverage for NM exception handling in L2 when only L2 NM
exception handler is registered

Verifies 3 different conditions for which #NM is generated and
handled in L2
1) CR0.TS is set - #NM is generated and handled in L2 exception
   handler
2) CR0.TS is cleared and CR0.EM is set - #NM is generated and
   handled in L2 exception handler
3) CR0.TS and CR0.EM are cleared - #NM is not generated

Signed-off-by: Manali Shukla <[e-mail]>
---
 x86/svm_tests.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 45 insertions(+)

Patch

diff --git a/x86/svm_tests.c b/x86/svm_tests.c
index 8ad6122..681272c 100644
--- a/x86/svm_tests.c
+++ b/x86/svm_tests.c
@@ -2962,6 +2962,50 @@  static bool vgif_check(struct svm_test *test)
     return get_test_stage(test) == 3;
 }
 
+static int nm_test_counter;
+
+static void guest_test_nm_handler(struct ex_regs *r)
+{
+    nm_test_counter++; 
+    write_cr0(read_cr0() & ~X86_CR0_TS);
+    write_cr0(read_cr0() & ~X86_CR0_EM);
+}
+
+static void svm_nm_test_guest(struct svm_test *test)
+{
+    asm volatile("fnop");
+}
+
+/* This test checks that:
+ *
+ * (a) If CR0.TS is set in L2, #NM is handled by L2 when
+ *     just an L2 handler is registered.
+ *
+ * (b) If CR0.TS is cleared and CR0.EM is set, #NM is handled
+ *     by L2 when just an l2 handler is registered.
+ *
+ * (c) If CR0.TS and CR0.EM are cleared in L2, no exception
+ *     is generated.
+ */
+
+static void svm_nm_test(void)
+{
+    handle_exception(NM_VECTOR, guest_test_nm_handler);
+    write_cr0(read_cr0() & ~X86_CR0_TS);
+    test_set_guest(svm_nm_test_guest);
+
+    vmcb->save.cr0 = vmcb->save.cr0 | X86_CR0_TS;
+    report(svm_vmrun() == SVM_EXIT_VMMCALL && nm_test_counter == 1,
+        "fnop with CR0.TS set in L2, #NM is triggered");
+
+    vmcb->save.cr0 = (vmcb->save.cr0 & ~X86_CR0_TS) | X86_CR0_EM;
+    report(svm_vmrun() == SVM_EXIT_VMMCALL && nm_test_counter == 2,
+        "fnop with CR0.EM set in L2, #NM is triggered");
+
+    vmcb->save.cr0 = vmcb->save.cr0 & ~(X86_CR0_TS | X86_CR0_EM);
+    report(svm_vmrun() == SVM_EXIT_VMMCALL && nm_test_counter == 2,
+        "fnop with CR0.TS and CR0.EM unset no #NM excpetion");
+}
 
 struct svm_test svm_tests[] = {
     { "null", default_supported, default_prepare,
@@ -3082,5 +3126,6 @@  struct svm_test svm_tests[] = {
     TEST(svm_vmrun_errata_test),
     TEST(svm_vmload_vmsave),
     TEST(svm_test_singlestep),
+    TEST(svm_nm_test),
     { NULL, NULL, NULL, NULL, NULL, NULL, NULL }
 };