[v6,14/30] KVM: selftests: TDX: Add TDX IO writes test

Commit Message

Sagi Shahar April 14, 2025, 9:47 p.m. UTC

The test verifies IO writes of various sizes from the guest to the host.

Signed-off-by: Sagi Shahar <[e-mail]>
---
 .../selftests/kvm/include/x86/tdx/tdcall.h    |  3 +
 tools/testing/selftests/kvm/x86/tdx_vm_test.c | 79 ++++++++++++++++++-
 2 files changed, 81 insertions(+), 1 deletion(-)

Patch

diff --git a/tools/testing/selftests/kvm/include/x86/tdx/tdcall.h b/tools/testing/selftests/kvm/include/x86/tdx/tdcall.h
index a6c966e93486..e7440f7fe259 100644
--- a/tools/testing/selftests/kvm/include/x86/tdx/tdcall.h
+++ b/tools/testing/selftests/kvm/include/x86/tdx/tdcall.h
@@ -7,6 +7,9 @@ 
 #include <linux/bits.h>
 #include <linux/types.h>
 
+#define TDG_VP_VMCALL_SUCCESS 0x0000000000000000
+#define TDG_VP_VMCALL_INVALID_OPERAND 0x8000000000000000
+
 #define TDX_HCALL_HAS_OUTPUT BIT(0)
 
 #define TDX_HYPERCALL_STANDARD 0
diff --git a/tools/testing/selftests/kvm/x86/tdx_vm_test.c b/tools/testing/selftests/kvm/x86/tdx_vm_test.c
index 22143d16e0d1..f646da032004 100644
--- a/tools/testing/selftests/kvm/x86/tdx_vm_test.c
+++ b/tools/testing/selftests/kvm/x86/tdx_vm_test.c
@@ -308,6 +308,81 @@  void verify_get_td_vmcall_info(void)
 	printf("\t ... PASSED\n");
 }
 
+#define TDX_IO_WRITES_TEST_PORT 0x51
+
+/*
+ * Verifies IO functionality by writing values of different sizes
+ * to the host.
+ */
+void guest_io_writes(void)
+{
+	uint64_t byte_4 = 0xFFABCDEF;
+	uint64_t byte_2 = 0xABCD;
+	uint64_t byte_1 = 0xAB;
+	uint64_t ret;
+
+	ret = tdg_vp_vmcall_instruction_io(TDX_IO_WRITES_TEST_PORT, 1,
+					   PORT_WRITE, &byte_1);
+	tdx_assert_error(ret);
+
+	ret = tdg_vp_vmcall_instruction_io(TDX_IO_WRITES_TEST_PORT, 2,
+					   PORT_WRITE, &byte_2);
+	tdx_assert_error(ret);
+
+	ret = tdg_vp_vmcall_instruction_io(TDX_IO_WRITES_TEST_PORT, 4,
+					   PORT_WRITE, &byte_4);
+	tdx_assert_error(ret);
+
+	/* Write an invalid number of bytes. */
+	ret = tdg_vp_vmcall_instruction_io(TDX_IO_WRITES_TEST_PORT, 5,
+					   PORT_WRITE, &byte_4);
+	tdx_assert_error(ret);
+
+	tdx_test_success();
+}
+
+void verify_guest_writes(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+	uint32_t byte_4;
+	uint16_t byte_2;
+	uint8_t byte_1;
+
+	vm = td_create();
+	td_initialize(vm, VM_MEM_SRC_ANONYMOUS, 0);
+	vcpu = td_vcpu_add(vm, 0, guest_io_writes);
+	td_finalize(vm);
+
+	printf("Verifying guest writes:\n");
+
+	tdx_run(vcpu);
+	tdx_test_assert_io(vcpu, TDX_IO_WRITES_TEST_PORT, 1, PORT_WRITE);
+	byte_1 = *(uint8_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+	tdx_run(vcpu);
+	tdx_test_assert_io(vcpu, TDX_IO_WRITES_TEST_PORT, 2, PORT_WRITE);
+	byte_2 = *(uint16_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+	tdx_run(vcpu);
+	tdx_test_assert_io(vcpu, TDX_IO_WRITES_TEST_PORT, 4, PORT_WRITE);
+	byte_4 = *(uint32_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+	TEST_ASSERT_EQ(byte_1, 0xAB);
+	TEST_ASSERT_EQ(byte_2, 0xABCD);
+	TEST_ASSERT_EQ(byte_4, 0xFFABCDEF);
+
+	td_vcpu_run(vcpu);
+	TEST_ASSERT_EQ(vcpu->run->exit_reason, KVM_EXIT_SYSTEM_EVENT);
+	TEST_ASSERT_EQ(vcpu->run->system_event.data[12], TDG_VP_VMCALL_INVALID_OPERAND);
+
+	tdx_run(vcpu);
+	tdx_test_assert_success(vcpu);
+
+	kvm_vm_free(vm);
+	printf("\t ... PASSED\n");
+}
+
 int main(int argc, char **argv)
 {
 	ksft_print_header();
@@ -315,7 +390,7 @@  int main(int argc, char **argv)
 	if (!is_tdx_enabled())
 		ksft_exit_skip("TDX is not supported by the KVM. Exiting.\n");
 
-	ksft_set_plan(5);
+	ksft_set_plan(6);
 	ksft_test_result(!run_in_new_process(&verify_td_lifecycle),
 			 "verify_td_lifecycle\n");
 	ksft_test_result(!run_in_new_process(&verify_report_fatal_error),
@@ -326,6 +401,8 @@  int main(int argc, char **argv)
 			 "verify_td_cpuid\n");
 	ksft_test_result(!run_in_new_process(&verify_get_td_vmcall_info),
 			 "verify_get_td_vmcall_info\n");
+	ksft_test_result(!run_in_new_process(&verify_guest_writes),
+			 "verify_guest_writes\n");
 
 	ksft_finished();
 	return 0;