[RFC PATCH v3 14/31] KVM: selftests: TDX: Add TDX IO writes test

[Ackerley Tng <ackerleytng@xxxxxxxxxx>]

From: Sagi Shahar <sagis@xxxxxxxxxx>

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


Signed-off-by: Sagi Shahar <sagis@xxxxxxxxxx>
Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
---
 .../selftests/kvm/include/x86_64/tdx/tdcall.h |  3 +
 .../selftests/kvm/x86_64/tdx_vm_tests.c       | 91 +++++++++++++++++++
 2 files changed, 94 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/x86_64/tdx/tdcall.h b/tools/testing/selftests/kvm/include/x86_64/tdx/tdcall.h
index 78001bfec9c8d..b5e94b7c48fa5 100644
--- a/tools/testing/selftests/kvm/include/x86_64/tdx/tdcall.h
+++ b/tools/testing/selftests/kvm/include/x86_64/tdx/tdcall.h
@@ -10,6 +10,9 @@
 #define TDG_VP_VMCALL_INSTRUCTION_IO_READ 0
 #define TDG_VP_VMCALL_INSTRUCTION_IO_WRITE 1
 
+#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_64/tdx_vm_tests.c b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
index 188442a734dca..ac23d1ad1e687 100644
--- a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
+++ b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
@@ -338,6 +338,96 @@ 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_1 = 0xAB;
+	uint64_t byte_2 = 0xABCD;
+	uint64_t byte_4 = 0xFFABCDEF;
+	uint64_t ret;
+
+	ret = tdg_vp_vmcall_instruction_io(TDX_IO_WRITES_TEST_PORT, 1,
+					TDG_VP_VMCALL_INSTRUCTION_IO_WRITE,
+					&byte_1);
+	if (ret)
+		tdx_test_fatal(ret);
+
+	ret = tdg_vp_vmcall_instruction_io(TDX_IO_WRITES_TEST_PORT, 2,
+					TDG_VP_VMCALL_INSTRUCTION_IO_WRITE,
+					&byte_2);
+	if (ret)
+		tdx_test_fatal(ret);
+
+	ret = tdg_vp_vmcall_instruction_io(TDX_IO_WRITES_TEST_PORT, 4,
+					TDG_VP_VMCALL_INSTRUCTION_IO_WRITE,
+					&byte_4);
+	if (ret)
+		tdx_test_fatal(ret);
+
+	// Write an invalid number of bytes.
+	ret = tdg_vp_vmcall_instruction_io(TDX_IO_WRITES_TEST_PORT, 5,
+					TDG_VP_VMCALL_INSTRUCTION_IO_WRITE,
+					&byte_4);
+	if (ret)
+		tdx_test_fatal(ret);
+
+	tdx_test_success();
+}
+
+void verify_guest_writes(void)
+{
+	struct kvm_vm *vm;
+	struct kvm_vcpu *vcpu;
+
+	uint8_t byte_1;
+	uint16_t byte_2;
+	uint32_t byte_4;
+
+	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");
+
+	vcpu_run(vcpu);
+	TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
+	TDX_TEST_ASSERT_IO(vcpu, TDX_IO_WRITES_TEST_PORT, 1,
+			TDG_VP_VMCALL_INSTRUCTION_IO_WRITE);
+	byte_1 = *(uint8_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+	vcpu_run(vcpu);
+	TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
+	TDX_TEST_ASSERT_IO(vcpu, TDX_IO_WRITES_TEST_PORT, 2,
+			TDG_VP_VMCALL_INSTRUCTION_IO_WRITE);
+	byte_2 = *(uint16_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+	vcpu_run(vcpu);
+	TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
+	TDX_TEST_ASSERT_IO(vcpu, TDX_IO_WRITES_TEST_PORT, 4,
+			TDG_VP_VMCALL_INSTRUCTION_IO_WRITE);
+	byte_4 = *(uint32_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+	ASSERT_EQ(byte_1, 0xAB);
+	ASSERT_EQ(byte_2, 0xABCD);
+	ASSERT_EQ(byte_4, 0xFFABCDEF);
+
+	vcpu_run(vcpu);
+	ASSERT_EQ(vcpu->run->exit_reason, KVM_EXIT_SYSTEM_EVENT);
+	ASSERT_EQ(vcpu->run->system_event.data[1], TDG_VP_VMCALL_INVALID_OPERAND);
+
+	vcpu_run(vcpu);
+	TDX_TEST_ASSERT_SUCCESS(vcpu);
+
+	kvm_vm_free(vm);
+	printf("\t ... PASSED\n");
+}
+
 int main(int argc, char **argv)
 {
 	setbuf(stdout, NULL);
@@ -352,6 +442,7 @@ int main(int argc, char **argv)
 	run_in_new_process(&verify_td_ioexit);
 	run_in_new_process(&verify_td_cpuid);
 	run_in_new_process(&verify_get_td_vmcall_info);
+	run_in_new_process(&verify_guest_writes);
 
 	return 0;
 }
-- 
2.39.0.246.g2a6d74b583-goog