Re: [RFC PATCH v5 10/29] KVM: selftests: TDX: Adding test case for TDX port IO

[Yan Zhao]

On Tue, Dec 12, 2023 at 12:46:25PM -0800, Sagi Shahar wrote:
> From: Erdem Aktas <erdemaktas@xxxxxxxxxx>
> 
> Verifies TDVMCALL<INSTRUCTION.IO> READ and WRITE operations.
> 
> Signed-off-by: Erdem Aktas <erdemaktas@xxxxxxxxxx>
> Signed-off-by: Sagi Shahar <sagis@xxxxxxxxxx>
> Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
> Signed-off-by: Ryan Afranji <afranji@xxxxxxxxxx>
> ---
>  .../kvm/include/x86_64/tdx/test_util.h        | 34 ++++++++
>  .../selftests/kvm/x86_64/tdx_vm_tests.c       | 82 +++++++++++++++++++
>  2 files changed, 116 insertions(+)
> 
> diff --git a/tools/testing/selftests/kvm/include/x86_64/tdx/test_util.h b/tools/testing/selftests/kvm/include/x86_64/tdx/test_util.h
> index 6d69921136bd..95a5d5be7f0b 100644
> --- a/tools/testing/selftests/kvm/include/x86_64/tdx/test_util.h
> +++ b/tools/testing/selftests/kvm/include/x86_64/tdx/test_util.h
> @@ -9,6 +9,40 @@
>  #define TDX_TEST_SUCCESS_PORT 0x30
>  #define TDX_TEST_SUCCESS_SIZE 4
>  
> +/**
> + * Assert that some IO operation involving tdg_vp_vmcall_instruction_io() was
> + * called in the guest.
> + */
> +#define TDX_TEST_ASSERT_IO(VCPU, PORT, SIZE, DIR)			\
> +	do {								\
> +		TEST_ASSERT((VCPU)->run->exit_reason == KVM_EXIT_IO,	\
> +			"Got exit_reason other than KVM_EXIT_IO: %u (%s)\n", \
> +			(VCPU)->run->exit_reason,			\
> +			exit_reason_str((VCPU)->run->exit_reason));	\
> +									\
> +		TEST_ASSERT(((VCPU)->run->exit_reason == KVM_EXIT_IO) && \
> +			((VCPU)->run->io.port == (PORT)) &&		\
> +			((VCPU)->run->io.size == (SIZE)) &&		\
> +			((VCPU)->run->io.direction == (DIR)),		\
> +			"Got unexpected IO exit values: %u (%s) %d %d %d\n", \
> +			(VCPU)->run->exit_reason,			\
> +			exit_reason_str((VCPU)->run->exit_reason),	\
> +			(VCPU)->run->io.port, (VCPU)->run->io.size,	\
> +			(VCPU)->run->io.direction);			\
> +	} while (0)
> +
> +/**
> + * Check and report if there was some failure in the guest, either an exception
> + * like a triple fault, or if a tdx_test_fatal() was hit.
> + */
> +#define TDX_TEST_CHECK_GUEST_FAILURE(VCPU)				\
> +	do {								\
> +		if ((VCPU)->run->exit_reason == KVM_EXIT_SYSTEM_EVENT)	\
> +			TEST_FAIL("Guest reported error. error code: %lld (0x%llx)\n", \
> +				(VCPU)->run->system_event.data[1],	\
> +				(VCPU)->run->system_event.data[1]);	\
> +	} while (0)
> +
>  /**
>   * Assert that tdx_test_success() was called in the guest.
>   */
> 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 8638c7bbedaa..75467c407ca7 100644
> --- a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
> +++ b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
> @@ -2,6 +2,7 @@
>  
>  #include <signal.h>
>  #include "kvm_util_base.h"
> +#include "tdx/tdcall.h"
>  #include "tdx/tdx.h"
>  #include "tdx/tdx_util.h"
>  #include "tdx/test_util.h"
> @@ -74,6 +75,86 @@ void verify_report_fatal_error(void)
>  	printf("\t ... PASSED\n");
>  }
>  
> +#define TDX_IOEXIT_TEST_PORT 0x50
> +
> +/*
> + * Verifies IO functionality by writing a |value| to a predefined port.
> + * Verifies that the read value is |value| + 1 from the same port.
> + * If all the tests are passed then write a value to port TDX_TEST_PORT
> + */
> +void guest_ioexit(void)
> +{
> +	uint64_t data_out, data_in, delta;
> +	uint64_t ret;
> +
> +	data_out = 0xAB;
> +	ret = tdg_vp_vmcall_instruction_io(TDX_IOEXIT_TEST_PORT, 1,
> +					TDG_VP_VMCALL_INSTRUCTION_IO_WRITE,
> +					&data_out);
> +	if (ret)
> +		tdx_test_fatal(ret);
> +
> +	ret = tdg_vp_vmcall_instruction_io(TDX_IOEXIT_TEST_PORT, 1,
> +					TDG_VP_VMCALL_INSTRUCTION_IO_READ,
> +					&data_in);
> +	if (ret)
> +		tdx_test_fatal(ret);
> +
> +	delta = data_in - data_out;
> +	if (delta != 1)
> +		tdx_test_fatal(ret);
> +
> +	tdx_test_success();
> +}
> +
> +void verify_td_ioexit(void)
> +{
> +	struct kvm_vm *vm;
> +	struct kvm_vcpu *vcpu;
> +
> +	uint32_t port_data;
> +
> +	vm = td_create();
> +	td_initialize(vm, VM_MEM_SRC_ANONYMOUS, 0);
> +	vcpu = td_vcpu_add(vm, 0, guest_ioexit);
> +	td_finalize(vm);
> +
> +	printf("Verifying TD IO Exit:\n");
> +
> +	/* Wait for guest to do a IO write */
> +	td_vcpu_run(vcpu);
> +	TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
This check is a vain, because the first VMExit from vcpu run is always
KVM_EXIT_IO caused by tdg_vp_vmcall_instruction_io().


> +	TDX_TEST_ASSERT_IO(vcpu, TDX_IOEXIT_TEST_PORT, 1,
> +			TDG_VP_VMCALL_INSTRUCTION_IO_WRITE);
> +	port_data = *(uint8_t *)((void *)vcpu->run + vcpu->run->io.data_offset);
> +
> +	printf("\t ... IO WRITE: OK\n");
So,  even if there's an error in emulating writing of TDX_IOEXIT_TEST_PORT,
and guest would then find a failure and trigger tdx_test_fatal(), this line
will still print "IO WRITE: OK", which is not right.

> +
> +	/*
> +	 * Wait for the guest to do a IO read. Provide the previous written data
> +	 * + 1 back to the guest
> +	 */
> +	td_vcpu_run(vcpu);
> +	TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
This check is a vain, too, as in  write case.

> +	TDX_TEST_ASSERT_IO(vcpu, TDX_IOEXIT_TEST_PORT, 1,
> +			TDG_VP_VMCALL_INSTRUCTION_IO_READ);
> +	*(uint8_t *)((void *)vcpu->run + vcpu->run->io.data_offset) = port_data + 1;
> +
> +	printf("\t ... IO READ: OK\n");
Same as in write case, this line should not be printed until after guest
finishing checking return code.

> +
> +	/*
> +	 * Wait for the guest to complete execution successfully. The read
> +	 * value is checked within the guest.
> +	 */
> +	td_vcpu_run(vcpu);
> +	TDX_TEST_CHECK_GUEST_FAILURE(vcpu);
> +	TDX_TEST_ASSERT_SUCCESS(vcpu);
> +
> +	printf("\t ... IO verify read/write values: OK\n");
> +	kvm_vm_free(vm);
> +	printf("\t ... PASSED\n");
> +}
> +
>  int main(int argc, char **argv)
>  {
>  	setbuf(stdout, NULL);
> @@ -85,6 +166,7 @@ int main(int argc, char **argv)
>  
>  	run_in_new_process(&verify_td_lifecycle);
>  	run_in_new_process(&verify_report_fatal_error);
> +	run_in_new_process(&verify_td_ioexit);
>  
>  	return 0;
>  }
> -- 
> 2.43.0.472.g3155946c3a-goog
> 
>