[RFC PATCH v2 08/17] KVM: selftest: TDX: Add TDX IO writes test

[Sagi Shahar <sagis@google.com>]

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

Google-Bug-Id: 235407183

Signed-off-by: Sagi Shahar <sagis@google.com>
---
 tools/testing/selftests/kvm/lib/x86_64/tdx.h  |  3 +
 .../selftests/kvm/x86_64/tdx_vm_tests.c       | 85 +++++++++++++++++++
 2 files changed, 88 insertions(+)

diff --git a/tools/testing/selftests/kvm/lib/x86_64/tdx.h b/tools/testing/selftests/kvm/lib/x86_64/tdx.h
index 39b000118e26..f1f44c2ad40e 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/tdx.h
+++ b/tools/testing/selftests/kvm/lib/x86_64/tdx.h
@@ -51,6 +51,9 @@
 #define _PAGE_RW            (1UL<<1)       /* writeable */
 #define _PAGE_PS            (1UL<<7)       /* page size bit*/
 
+#define TDX_VMCALL_SUCCESS 0x0000000000000000
+#define TDX_VMCALL_INVALID_OPERAND 0x8000000000000000
+
 #define TDX_GET_TD_VM_CALL_INFO 0x10000
 #define TDX_REPORT_FATAL_ERROR 0x10003
 #define TDX_INSTRUCTION_IO 30
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 cf8260db1f5b..ee60f77fe38e 100644
--- a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
+++ b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
@@ -489,6 +489,90 @@ void verify_get_td_vmcall_info(void)
 	printf("\t ... PASSED\n");
 }
 
+/*
+ * Verifies IO functionality by writing values of different sizes
+ * to the host.
+ */
+TDX_GUEST_FUNCTION(guest_io_writes)
+{
+	uint64_t byte_1 = 0xAB;
+	uint64_t byte_2 = 0xABCD;
+	uint64_t byte_4 = 0xFFABCDEF;
+	uint64_t ret;
+
+	ret = tdvmcall_io(TDX_TEST_PORT, 1, TDX_IO_WRITE, &byte_1);
+	if (ret)
+		tdvmcall_fatal(ret);
+
+	ret = tdvmcall_io(TDX_TEST_PORT, 2, TDX_IO_WRITE, &byte_2);
+	if (ret)
+		tdvmcall_fatal(ret);
+
+	ret = tdvmcall_io(TDX_TEST_PORT, 4, TDX_IO_WRITE, &byte_4);
+	if (ret)
+		tdvmcall_fatal(ret);
+
+	// Write an invalid number of bytes.
+	ret = tdvmcall_io(TDX_TEST_PORT, 5, TDX_IO_WRITE, &byte_4);
+	if (ret)
+		tdvmcall_fatal(ret);
+
+	tdvmcall_success();
+}
+
+void verify_guest_writes(void)
+{
+	struct kvm_vcpu *vcpu;
+	struct kvm_vm *vm;
+	uint8_t byte_1;
+	uint16_t byte_2;
+	uint32_t byte_4;
+
+	printf("Verifying guest writes:\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_io_writes,
+			     TDX_FUNCTION_SIZE(guest_io_writes), 0);
+	finalize_td_memory(vm);
+
+	vcpu_run(vcpu);
+	CHECK_GUEST_FAILURE(vcpu);
+	CHECK_IO(vcpu, TDX_TEST_PORT, 1, TDX_IO_WRITE);
+	byte_1 = *(uint8_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+	vcpu_run(vcpu);
+	CHECK_GUEST_FAILURE(vcpu);
+	CHECK_IO(vcpu, TDX_TEST_PORT, 2, TDX_IO_WRITE);
+	byte_2 = *(uint16_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
+
+	vcpu_run(vcpu);
+	CHECK_GUEST_FAILURE(vcpu);
+	CHECK_IO(vcpu, TDX_TEST_PORT, 4, TDX_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], TDX_VMCALL_INVALID_OPERAND);
+
+	vcpu_run(vcpu);
+	CHECK_GUEST_COMPLETION(vcpu);
+
+	kvm_vm_free(vm);
+	printf("\t ... PASSED\n");
+}
+
 int main(int argc, char **argv)
 {
 	if (!is_tdx_enabled()) {
@@ -501,6 +585,7 @@ 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;
 }
-- 
2.37.2.789.g6183377224-goog