[RFC PATCH v2 11/17] KVM: selftest: TDX: Add TDX HLT exit test

[Sagi Shahar <sagis@google.com>]

The test verifies that the guest runs TDVMCALL<INSTRUCTION.HLT> and the
guest vCPU enters to the halted state.

Signed-off-by: Erdem Aktas <erdemaktas@google.com>
Signed-off-by: Sagi Shahar <sagis@google.com>
---
 tools/testing/selftests/kvm/lib/x86_64/tdx.h  | 16 ++++
 .../selftests/kvm/x86_64/tdx_vm_tests.c       | 88 +++++++++++++++++++
 2 files changed, 104 insertions(+)

diff --git a/tools/testing/selftests/kvm/lib/x86_64/tdx.h b/tools/testing/selftests/kvm/lib/x86_64/tdx.h
index 263834979727..b11200028546 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/tdx.h
+++ b/tools/testing/selftests/kvm/lib/x86_64/tdx.h
@@ -56,6 +56,7 @@
 
 #define TDX_GET_TD_VM_CALL_INFO 0x10000
 #define TDX_REPORT_FATAL_ERROR 0x10003
+#define TDX_INSTRUCTION_HLT 12
 #define TDX_INSTRUCTION_IO 30
 #define TDX_INSTRUCTION_RDMSR 31
 #define TDX_INSTRUCTION_WRMSR 32
@@ -292,6 +293,21 @@ static inline uint64_t tdvmcall_wrmsr(uint64_t index, uint64_t value)
 	return regs.r10;
 }
 
+/*
+ * Execute HLT instruction.
+ */
+static inline uint64_t tdvmcall_hlt(uint64_t interrupt_blocked_flag)
+{
+	struct kvm_regs regs;
+
+	memset(&regs, 0, sizeof(regs));
+	regs.r11 = TDX_INSTRUCTION_HLT;
+	regs.r12 = interrupt_blocked_flag;
+	regs.rcx = 0x1C00;
+	tdcall(&regs);
+	return regs.r10;
+}
+
 /*
  * Reports a 32 bit value from the guest to user space using a TDVM IO call.
  * Data is reported on port TDX_DATA_REPORT_PORT.
diff --git a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
index fb3b8de7e5cd..39604aac54bd 100644
--- a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
+++ b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
@@ -883,6 +883,93 @@ void verify_guest_msr_writes(void)
 	printf("\t ... PASSED\n");
 }
 
+/*
+ * Verifies HLT functionality.
+ */
+TDX_GUEST_FUNCTION(guest_hlt)
+{
+	uint64_t ret;
+	uint64_t interrupt_blocked_flag;
+
+	interrupt_blocked_flag = 0;
+	ret = tdvmcall_hlt(interrupt_blocked_flag);
+	if (ret)
+		tdvmcall_fatal(ret);
+
+	tdvmcall_success();
+}
+
+void _verify_guest_hlt(int signum);
+
+void wake_me(int interval)
+{
+	struct sigaction action;
+
+	action.sa_handler = _verify_guest_hlt;
+	sigemptyset(&action.sa_mask);
+	action.sa_flags = 0;
+
+	TEST_ASSERT(sigaction(SIGALRM, &action, NULL) == 0,
+		    "Could not set the alarm handler!");
+
+	alarm(interval);
+}
+
+void _verify_guest_hlt(int signum)
+{
+	static struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+
+	/*
+	 * This function will also be called by SIGALRM handler to check the
+	 * vCPU MP State. If vm has been initialized, then we are in the signal
+	 * handler. Check the MP state and let the guest run again.
+	 */
+	if (vcpu != NULL) {
+		struct kvm_mp_state mp_state;
+
+		vcpu_mp_state_get(vcpu, &mp_state);
+		ASSERT_EQ(mp_state.mp_state, KVM_MP_STATE_HALTED);
+
+		/* Let the guest to run and finish the test.*/
+		mp_state.mp_state = KVM_MP_STATE_RUNNABLE;
+		vcpu_mp_state_set(vcpu, &mp_state);
+		return;
+	}
+
+	printf("Verifying HLT:\n");
+
+	/* Create a TD VM with no memory.*/
+	vm = vm_create_tdx();
+
+	/* Allocate TD guest memory and initialize the TD.*/
+	initialize_td(vm);
+
+	/* Initialize the TD vcpu and copy the test code to the guest memory.*/
+	vcpu = vm_vcpu_add_tdx(vm, 0);
+
+	/* Setup and initialize VM memory */
+	prepare_source_image(vm, guest_hlt,
+			     TDX_FUNCTION_SIZE(guest_hlt), 0);
+	finalize_td_memory(vm);
+
+	printf("\t ... Running guest\n");
+
+	/* Wait 1 second for guest to execute HLT */
+	wake_me(1);
+	vcpu_run(vcpu);
+
+	CHECK_GUEST_COMPLETION(vcpu);
+
+	kvm_vm_free(vm);
+	printf("\t ... PASSED\n");
+}
+
+void verify_guest_hlt(void)
+{
+	_verify_guest_hlt(0);
+}
+
 int main(int argc, char **argv)
 {
 	if (!is_tdx_enabled()) {
@@ -899,6 +986,7 @@ int main(int argc, char **argv)
 	run_in_new_process(&verify_guest_reads);
 	run_in_new_process(&verify_guest_msr_reads);
 	run_in_new_process(&verify_guest_msr_writes);
+	run_in_new_process(&verify_guest_hlt);
 
 	return 0;
 }
-- 
2.37.2.789.g6183377224-goog