From: Sean Christopherson <seanjc@google.com>
Date: Fri, 19 Sep 2025 22:32:57 +0000 (-0700)
Subject: KVM: selftests: Verify MSRs are (not) in save/restore list when (un)supported
X-Git-Tag: v6.18-rc1~55^2~5^2~1
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=947ab90c91983c965acb994455734aae19317596;p=thirdparty%2Flinux.git

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 54ef9c539eb3..40d918aedce6 100644
--- 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);