KVM: selftests: Verify MSRs are (not) in save/restore list when (un)supported

Add a check in the MSRs test to verify that KVM's reported support for
MSRs with feature bits is consistent between KVM's MSR save/restore lists
and KVM's supported CPUID.

To deal with Intel's wonderful decision to bundle IBT and SHSTK under CET,
track the "second" feature to avoid false failures when running on a CPU
with only one of IBT or SHSTK.

Reviewed-by: Chao Gao <chao.gao@intel.com>
Link: https://lore.kernel.org/r/20250919223258.1604852-51-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/tools/testing/selftests/kvm/x86/msrs_test.c b/tools/testing/selftests/kvm/x86/msrs_test.c
index 54ef9c539eb31808a434e5dad1ab4db87ff839c4..40d918aedce672c073d16bf9ca37216ca56cf615 100644 (file)
--- a/tools/testing/selftests/kvm/x86/msrs_test.c
+++ b/tools/testing/selftests/kvm/x86/msrs_test.c
@@ -444,12 +444,29 @@ static void test_msrs(void)
        }
 
        for (idx = 0; idx < ARRAY_SIZE(__msrs); idx++) {
-               if (msrs[idx].is_kvm_defined) {
+               struct kvm_msr *msr = &msrs[idx];
+
+               if (msr->is_kvm_defined) {
                        for (i = 0; i < NR_VCPUS; i++)
                                host_test_kvm_reg(vcpus[i]);
                        continue;
                }
 
+               /*
+                * Verify KVM_GET_SUPPORTED_CPUID and KVM_GET_MSR_INDEX_LIST
+                * are consistent with respect to MSRs whose existence is
+                * enumerated via CPUID.  Skip the check for FS/GS.base MSRs,
+                * as they aren't reported in the save/restore list since their
+                * state is managed via SREGS.
+                */
+               TEST_ASSERT(msr->index == MSR_FS_BASE || msr->index == MSR_GS_BASE ||
+                           kvm_msr_is_in_save_restore_list(msr->index) ==
+                           (kvm_cpu_has(msr->feature) || kvm_cpu_has(msr->feature2)),
+                           "%s %s in save/restore list, but %s according to CPUID", msr->name,
+                           kvm_msr_is_in_save_restore_list(msr->index) ? "is" : "isn't",
+                           (kvm_cpu_has(msr->feature) || kvm_cpu_has(msr->feature2)) ?
+                           "supported" : "unsupported");
+
                sync_global_to_guest(vm, idx);
 
                vcpus_run(vcpus, NR_VCPUS);