KVM: selftests: evmcs_test: Test that KVM_STATE_NESTED_EVMCS is never lost

Do KVM_GET_NESTED_STATE/KVM_SET_NESTED_STATE for a freshly restored VM
(before the first KVM_RUN) to check that KVM_STATE_NESTED_EVMCS is not
lost.
Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210526132026.270394-12-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

tools/testing/selftests/kvm/x86_64/evmcs_test.c

@@ -112,14 +112,38 @@ void inject_nmi(struct kvm_vm *vm)
 	vcpu_events_set(vm, VCPU_ID, &events);
 }
 
+static void save_restore_vm(struct kvm_vm *vm)
+{
+	struct kvm_regs regs1, regs2;
+	struct kvm_x86_state *state;
+
+	state = vcpu_save_state(vm, VCPU_ID);
+	memset(&regs1, 0, sizeof(regs1));
+	vcpu_regs_get(vm, VCPU_ID, &regs1);
+
+	kvm_vm_release(vm);
+
+	/* Restore state in a new VM.  */
+	kvm_vm_restart(vm, O_RDWR);
+	vm_vcpu_add(vm, VCPU_ID);
+	vcpu_set_hv_cpuid(vm, VCPU_ID);
+	vcpu_enable_evmcs(vm, VCPU_ID);
+	vcpu_load_state(vm, VCPU_ID, state);
+	free(state);
+
+	memset(&regs2, 0, sizeof(regs2));
+	vcpu_regs_get(vm, VCPU_ID, &regs2);
+	TEST_ASSERT(!memcmp(&regs1, &regs2, sizeof(regs2)),
+		    "Unexpected register values after vcpu_load_state; rdi: %lx rsi: %lx",
+		    (ulong) regs2.rdi, (ulong) regs2.rsi);
+}
+
 int main(int argc, char *argv[])
 {
 	vm_vaddr_t vmx_pages_gva = 0;
 
-	struct kvm_regs regs1, regs2;
 	struct kvm_vm *vm;
 	struct kvm_run *run;
-	struct kvm_x86_state *state;
 	struct ucall uc;
 	int stage;
 
@@ -136,10 +160,6 @@ int main(int argc, char *argv[])
 	vcpu_set_hv_cpuid(vm, VCPU_ID);
 	vcpu_enable_evmcs(vm, VCPU_ID);
 
-	run = vcpu_state(vm, VCPU_ID);
-
-	vcpu_regs_get(vm, VCPU_ID, &regs1);
-
 	vcpu_alloc_vmx(vm, &vmx_pages_gva);
 	vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_gva);
 
@@ -151,6 +171,7 @@ int main(int argc, char *argv[])
 	pr_info("Running L1 which uses EVMCS to run L2\n");
 
 	for (stage = 1;; stage++) {
+		run = vcpu_state(vm, VCPU_ID);
 		_vcpu_run(vm, VCPU_ID);
 		TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
 			    "Stage %d: unexpected exit reason: %u (%s),\n",
@@ -175,32 +196,23 @@ int main(int argc, char *argv[])
 			    uc.args[1] == stage, "Stage %d: Unexpected register values vmexit, got %lx",
 			    stage, (ulong)uc.args[1]);
 
-		state = vcpu_save_state(vm, VCPU_ID);
-		memset(&regs1, 0, sizeof(regs1));
-		vcpu_regs_get(vm, VCPU_ID, &regs1);
-
-		kvm_vm_release(vm);
-
-		/* Restore state in a new VM.  */
-		kvm_vm_restart(vm, O_RDWR);
-		vm_vcpu_add(vm, VCPU_ID);
-		vcpu_set_hv_cpuid(vm, VCPU_ID);
-		vcpu_enable_evmcs(vm, VCPU_ID);
-		vcpu_load_state(vm, VCPU_ID, state);
-		run = vcpu_state(vm, VCPU_ID);
-		free(state);
-
-		memset(&regs2, 0, sizeof(regs2));
-		vcpu_regs_get(vm, VCPU_ID, &regs2);
-		TEST_ASSERT(!memcmp(&regs1, &regs2, sizeof(regs2)),
-			    "Unexpected register values after vcpu_load_state; rdi: %lx rsi: %lx",
-			    (ulong) regs2.rdi, (ulong) regs2.rsi);
+		save_restore_vm(vm);
 
 		/* Force immediate L2->L1 exit before resuming */
 		if (stage == 8) {
 			pr_info("Injecting NMI into L1 before L2 had a chance to run after restore\n");
 			inject_nmi(vm);
 		}
+
+		/*
+		 * Do KVM_GET_NESTED_STATE/KVM_SET_NESTED_STATE for a freshly
+		 * restored VM (before the first KVM_RUN) to check that
+		 * KVM_STATE_NESTED_EVMCS is not lost.
+		 */
+		if (stage == 9) {
+			pr_info("Trying extra KVM_GET_NESTED_STATE/KVM_SET_NESTED_STATE cycle\n");
+			save_restore_vm(vm);
+		}
 	}
 
 done: