Re: [PATCH v8 18/30] KVM: selftests: TDX: Add TDX MMIO reads test

[Binbin Wu <binbin.wu@linux.intel.com>]

On 8/8/2025 4:16 AM, Sagi Shahar wrote:
[...]
> diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/test_util.c b/tools/testing/selftests/kvm/lib/x86/tdx/test_util.c
> index 8c3b6802c37e..f92ddda2d1ac 100644
> --- a/tools/testing/selftests/kvm/lib/x86/tdx/test_util.c
> +++ b/tools/testing/selftests/kvm/lib/x86/tdx/test_util.c
> @@ -31,6 +31,25 @@ void tdx_test_assert_io(struct kvm_vcpu *vcpu, uint16_t port, uint8_t size,
>   		    vcpu->run->io.direction);
>   }
>   
> +void tdx_test_assert_mmio(struct kvm_vcpu *vcpu, uint64_t phys_addr,
> +			  uint32_t size, uint8_t is_write)
> +{
> +	TEST_ASSERT(vcpu->run->exit_reason == KVM_EXIT_MMIO,
> +		    "Got exit_reason other than KVM_EXIT_MMIO: %u (%s)\n",
> +		    vcpu->run->exit_reason,
> +		    exit_reason_str(vcpu->run->exit_reason));
> +
> +	TEST_ASSERT(vcpu->run->exit_reason == KVM_EXIT_MMIO &&
It's already checked above.

> +		    vcpu->run->mmio.phys_addr == phys_addr &&
> +		    vcpu->run->mmio.len == size &&
> +		    vcpu->run->mmio.is_write == is_write,
> +		    "Got an unexpected MMIO exit values: %u (%s) %llu %u %u\n",
> +		    vcpu->run->exit_reason,
> +		    exit_reason_str(vcpu->run->exit_reason),
> +		    vcpu->run->mmio.phys_addr, vcpu->run->mmio.len,
> +		    vcpu->run->mmio.is_write);
> +}
> +
>   void tdx_run(struct kvm_vcpu *vcpu)
>   {
>   	td_vcpu_run(vcpu);
> diff --git a/tools/testing/selftests/kvm/x86/tdx_vm_test.c b/tools/testing/selftests/kvm/x86/tdx_vm_test.c
> index 720ef5e87071..563f1025c8a3 100644
> --- a/tools/testing/selftests/kvm/x86/tdx_vm_test.c
> +++ b/tools/testing/selftests/kvm/x86/tdx_vm_test.c
> @@ -719,6 +719,91 @@ void verify_guest_hlt(void)
>   	_verify_guest_hlt(0);
>   }
>   
> +/* Pick any address that was not mapped into the guest to test MMIO */
> +#define TDX_MMIO_TEST_ADDR 0x200000000
> +#define MMIO_SYNC_VALUE 0x42
> +
> +void guest_mmio_reads(void)
> +{
> +	uint64_t mmio_test_addr = TDX_MMIO_TEST_ADDR | tdx_s_bit;
> +	uint64_t data;
> +	uint64_t ret;
> +
> +	ret = tdg_vp_vmcall_ve_request_mmio_read(mmio_test_addr, 1, &data);
> +	tdx_assert_error(ret);
> +	if (data != 0x12)
> +		tdx_test_fatal(1);
> +
> +	ret = tdg_vp_vmcall_ve_request_mmio_read(mmio_test_addr, 2, &data);
> +	tdx_assert_error(ret);
> +	if (data != 0x1234)
> +		tdx_test_fatal(2);
> +
> +	ret = tdg_vp_vmcall_ve_request_mmio_read(mmio_test_addr, 4, &data);
> +	tdx_assert_error(ret);
> +	if (data != 0x12345678)
> +		tdx_test_fatal(4);
> +
> +	ret = tdg_vp_vmcall_ve_request_mmio_read(mmio_test_addr, 8, &data);
> +	tdx_assert_error(ret);
> +	if (data != 0x1234567890ABCDEF)
> +		tdx_test_fatal(8);
> +
> +	/* Make sure host and guest are synced to the same point of execution */
> +	tdx_test_report_to_user_space(MMIO_SYNC_VALUE);
Is this step necessary?


> +
> +	/* Read an invalid number of bytes. */
> +	ret = tdg_vp_vmcall_ve_request_mmio_read(mmio_test_addr, 10, &data);
> +	tdx_assert_error(ret);
> +
> +	tdx_test_success();
> +}
> +
> +/*
> + * Verifies guest MMIO reads.
> + */
> +void verify_mmio_reads(void)
> +{
> +	struct kvm_vcpu *vcpu;
> +	struct kvm_vm *vm;
> +
> +	vm = td_create();
> +	td_initialize(vm, VM_MEM_SRC_ANONYMOUS, 0);
> +	vcpu = td_vcpu_add(vm, 0, guest_mmio_reads);
> +	td_finalize(vm);
> +
> +	printf("Verifying TD MMIO reads:\n");
> +
> +	tdx_run(vcpu);
> +	tdx_test_assert_mmio(vcpu, TDX_MMIO_TEST_ADDR, 1, MMIO_READ);
> +	*(uint8_t *)vcpu->run->mmio.data = 0x12;
> +
> +	tdx_run(vcpu);
> +	tdx_test_assert_mmio(vcpu, TDX_MMIO_TEST_ADDR, 2, MMIO_READ);
> +	*(uint16_t *)vcpu->run->mmio.data = 0x1234;
> +
> +	tdx_run(vcpu);
> +	tdx_test_assert_mmio(vcpu, TDX_MMIO_TEST_ADDR, 4, MMIO_READ);
> +	*(uint32_t *)vcpu->run->mmio.data = 0x12345678;
> +
> +	tdx_run(vcpu);
> +	tdx_test_assert_mmio(vcpu, TDX_MMIO_TEST_ADDR, 8, MMIO_READ);
> +	*(uint64_t *)vcpu->run->mmio.data = 0x1234567890ABCDEF;
> +
> +	tdx_run(vcpu);
> +	TEST_ASSERT_EQ(tdx_test_read_report_from_guest(vcpu), MMIO_SYNC_VALUE);
> +
> +	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();
> @@ -726,7 +811,7 @@ 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(10);
> +	ksft_set_plan(11);
>   	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),
> @@ -747,6 +832,8 @@ int main(int argc, char **argv)
>   			 "verify_guest_msr_reads\n");
>   	ksft_test_result(!run_in_new_process(&verify_guest_hlt),
>   			 "verify_guest_hlt\n");
> +	ksft_test_result(!run_in_new_process(&verify_mmio_reads),
> +			 "verify_mmio_reads\n");
>   
>   	ksft_finished();
>   	return 0;