Re: [PATCH v8 09/30] KVM: selftests: TDX: Add TDX lifecycle test

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

On 8/8/2025 4:16 AM, Sagi Shahar wrote:
> From: Erdem Aktas <erdemaktas@google.com>
>
> Adding a test to verify TDX lifecycle by creating a TD and running a
> dummy TDG.VP.VMCALL <Instruction.IO> inside it.
>
> Co-developed-by: Sagi Shahar <sagis@google.com>
> Signed-off-by: Sagi Shahar <sagis@google.com>
> Co-developed-by: Ackerley Tng <ackerleytng@google.com>
> Signed-off-by: Ackerley Tng <ackerleytng@google.com>
> Co-developed-by: Reinette Chatre <reinette.chatre@intel.com>
> Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
> Signed-off-by: Erdem Aktas <erdemaktas@google.com>
> Signed-off-by: Sagi Shahar <sagis@google.com>
> ---
>   tools/testing/selftests/kvm/Makefile.kvm      |  4 +
>   .../selftests/kvm/include/x86/tdx/tdcall.h    | 32 +++++++
>   .../selftests/kvm/include/x86/tdx/tdx.h       | 12 +++
>   .../selftests/kvm/include/x86/tdx/test_util.h | 41 ++++++++
>   .../selftests/kvm/lib/x86/tdx/tdcall.S        | 95 +++++++++++++++++++
>   tools/testing/selftests/kvm/lib/x86/tdx/tdx.c | 27 ++++++
>   .../selftests/kvm/lib/x86/tdx/test_util.c     | 61 ++++++++++++
>   tools/testing/selftests/kvm/x86/tdx_vm_test.c | 47 +++++++++
>   8 files changed, 319 insertions(+)
>   create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/tdcall.h
>   create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/tdx.h
>   create mode 100644 tools/testing/selftests/kvm/include/x86/tdx/test_util.h
>   create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/tdcall.S
>   create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/tdx.c
>   create mode 100644 tools/testing/selftests/kvm/lib/x86/tdx/test_util.c
>   create mode 100644 tools/testing/selftests/kvm/x86/tdx_vm_test.c

It's better to split the patch to the lib/utility part and the test case part.

>
> diff --git a/tools/testing/selftests/kvm/Makefile.kvm b/tools/testing/selftests/kvm/Makefile.kvm
> index b429c92e07d8..4a147d498bd2 100644
> --- a/tools/testing/selftests/kvm/Makefile.kvm
> +++ b/tools/testing/selftests/kvm/Makefile.kvm
> @@ -31,6 +31,9 @@ LIBKVM_x86 += lib/x86/ucall.c
>   LIBKVM_x86 += lib/x86/vmx.c
>   LIBKVM_x86 += lib/x86/tdx/tdx_util.c
>   LIBKVM_x86 += lib/x86/tdx/td_boot.S
> +LIBKVM_x86 += lib/x86/tdx/tdcall.S
> +LIBKVM_x86 += lib/x86/tdx/tdx.c
> +LIBKVM_x86 += lib/x86/tdx/test_util.c
>   
>   LIBKVM_arm64 += lib/arm64/gic.c
>   LIBKVM_arm64 += lib/arm64/gic_v3.c
> @@ -148,6 +151,7 @@ TEST_GEN_PROGS_x86 += rseq_test
>   TEST_GEN_PROGS_x86 += steal_time
>   TEST_GEN_PROGS_x86 += system_counter_offset_test
>   TEST_GEN_PROGS_x86 += pre_fault_memory_test
> +TEST_GEN_PROGS_x86 += x86/tdx_vm_test
>   
>   # Compiled outputs used by test targets
>   TEST_GEN_PROGS_EXTENDED_x86 += x86/nx_huge_pages_test
> diff --git a/tools/testing/selftests/kvm/include/x86/tdx/tdcall.h b/tools/testing/selftests/kvm/include/x86/tdx/tdcall.h
> new file mode 100644
> index 000000000000..a6c966e93486
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/include/x86/tdx/tdcall.h
> @@ -0,0 +1,32 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/* Adapted from arch/x86/include/asm/shared/tdx.h */
> +
> +#ifndef SELFTESTS_TDX_TDCALL_H
> +#define SELFTESTS_TDX_TDCALL_H
> +
> +#include <linux/bits.h>
> +#include <linux/types.h>
> +
> +#define TDX_HCALL_HAS_OUTPUT BIT(0)
> +
> +#define TDX_HYPERCALL_STANDARD 0
> +
> +/*
> + * Used in __tdx_hypercall() to pass down and get back registers' values of
> + * the TDCALL instruction when requesting services from the VMM.
> + *
> + * This is a software only structure and not part of the TDX module/VMM ABI.
> + */
> +struct tdx_hypercall_args {
> +	u64 r10;
> +	u64 r11;
> +	u64 r12;
> +	u64 r13;
> +	u64 r14;
> +	u64 r15;
> +};
> +
> +/* Used to request services from the VMM */
> +u64 __tdx_hypercall(struct tdx_hypercall_args *args, unsigned long flags);
> +
> +#endif // SELFTESTS_TDX_TDCALL_H
> diff --git a/tools/testing/selftests/kvm/include/x86/tdx/tdx.h b/tools/testing/selftests/kvm/include/x86/tdx/tdx.h
> new file mode 100644
> index 000000000000..a7161efe4ee2
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/include/x86/tdx/tdx.h
> @@ -0,0 +1,12 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#ifndef SELFTEST_TDX_TDX_H
> +#define SELFTEST_TDX_TDX_H
> +
> +#include <stdint.h>
> +
> +#define TDG_VP_VMCALL_INSTRUCTION_IO 30
> +
> +uint64_t tdg_vp_vmcall_instruction_io(uint64_t port, uint64_t size,
> +				      uint64_t write, uint64_t *data);
> +
> +#endif // SELFTEST_TDX_TDX_H
> diff --git a/tools/testing/selftests/kvm/include/x86/tdx/test_util.h b/tools/testing/selftests/kvm/include/x86/tdx/test_util.h
> new file mode 100644
> index 000000000000..07d63bf1ffe1
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/include/x86/tdx/test_util.h
> @@ -0,0 +1,41 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#ifndef SELFTEST_TDX_TEST_UTIL_H
> +#define SELFTEST_TDX_TEST_UTIL_H
> +
> +#include <stdbool.h>
> +
> +#include "tdcall.h"
> +
> +#define TDX_TEST_SUCCESS_PORT 0x30
> +#define TDX_TEST_SUCCESS_SIZE 4
> +
> +/* Port I/O direction */
> +#define PORT_READ	0
> +#define PORT_WRITE	1
> +
> +/*
> + * Run a test in a new process.
> + *
> + * There might be multiple tests running and if one test fails, it will
> + * prevent the subsequent tests to run due to how tests are failing with
> + * TEST_ASSERT function. run_in_new_process() will run a test in a new process
> + * context and wait for it to finish or fail to prevent TEST_ASSERT to kill the
> + * main testing process.
> + */
> +int run_in_new_process(void (*func)(void));
> +
> +/*
> + * Verify that the TDX is supported by KVM.
> + */
> +bool is_tdx_enabled(void);
> +
> +/*
> + * Report test success to userspace.
> + *
> + * Use tdx_test_assert_success() to assert that this function was called in the
> + * guest.
> + */
> +void tdx_test_success(void);
> +void tdx_test_assert_success(struct kvm_vcpu *vcpu);
> +
> +#endif // SELFTEST_TDX_TEST_UTIL_H
> diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/tdcall.S b/tools/testing/selftests/kvm/lib/x86/tdx/tdcall.S
> new file mode 100644
> index 000000000000..b10769d1d557
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdcall.S
> @@ -0,0 +1,95 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/* Adapted from arch/x86/coco/tdx/tdcall.S */
> +
> +/*
> + * TDCALL is supported in Binutils >= 2.36, add it for older version.
> + */
> +#define tdcall		.byte 0x66,0x0f,0x01,0xcc
> +
> +#define TDX_HYPERCALL_r10 0 /* offsetof(struct tdx_hypercall_args, r10) */
> +#define TDX_HYPERCALL_r11 8 /* offsetof(struct tdx_hypercall_args, r11) */
> +#define TDX_HYPERCALL_r12 16 /* offsetof(struct tdx_hypercall_args, r12) */
> +#define TDX_HYPERCALL_r13 24 /* offsetof(struct tdx_hypercall_args, r13) */
> +#define TDX_HYPERCALL_r14 32 /* offsetof(struct tdx_hypercall_args, r14) */
> +#define TDX_HYPERCALL_r15 40 /* offsetof(struct tdx_hypercall_args, r15) */
> +

As Sean suggested in an earlier patch, replicating the functionality of the
kernel's OFFSET() could remove the hard-coded offset.

> +/*
> + * Bitmasks of exposed registers (with VMM).
> + */
> +#define TDX_R10 0x400
> +#define TDX_R11 0x800
> +#define TDX_R12 0x1000
> +#define TDX_R13 0x2000
> +#define TDX_R14 0x4000
> +#define TDX_R15 0x8000

Is BIT() better?

> +
> +#define TDX_HCALL_HAS_OUTPUT 0x1
> +
> +/*
> + * These registers are clobbered to hold arguments for each
> + * TDVMCALL. They are safe to expose to the VMM.
> + * Each bit in this mask represents a register ID. Bit field
> + * details can be found in TDX GHCI specification, section
> + * titled "TDCALL [TDG.VP.VMCALL] leaf".
> + */
> +#define TDVMCALL_EXPOSE_REGS_MASK	( TDX_R10 | TDX_R11 | \
> +					  TDX_R12 | TDX_R13 | \
> +					  TDX_R14 | TDX_R15 )

#define TDVMCALL_EXPOSE_REGS_MASK    \
         (TDX_R10 | TDX_R11 | TDX_R12 | TDX_R13 | TDX_R14 | TDX_R15)

to save one line?
> +
> +.code64
> +.section .text
> +
> +.globl __tdx_hypercall
> +.type __tdx_hypercall, @function
> +__tdx_hypercall:
> +	/* Set up stack frame */
> +	push %rbp
> +	movq %rsp, %rbp
> +
> +	/* Save callee-saved GPRs as mandated by the x86_64 ABI */
> +	push %r15
> +	push %r14
> +	push %r13
> +	push %r12
> +
> +	/* Mangle function call ABI into TDCALL ABI: */
> +	/* Set TDCALL leaf ID (TDVMCALL (0)) in RAX */
> +	xor %eax, %eax
> +
> +	/* Copy hypercall registers from arg struct: */
> +	movq TDX_HYPERCALL_r10(%rdi), %r10
> +	movq TDX_HYPERCALL_r11(%rdi), %r11
> +	movq TDX_HYPERCALL_r12(%rdi), %r12
> +	movq TDX_HYPERCALL_r13(%rdi), %r13
> +	movq TDX_HYPERCALL_r14(%rdi), %r14
> +	movq TDX_HYPERCALL_r15(%rdi), %r15
> +
> +	movl $TDVMCALL_EXPOSE_REGS_MASK, %ecx
> +
> +	tdcall
> +
> +	/* TDVMCALL leaf return code is in R10 */
> +	movq %r10, %rax
> +
> +	/* Copy hypercall result registers to arg struct if needed */
> +	testq $TDX_HCALL_HAS_OUTPUT, %rsi
> +	jz .Lout
> +
> +	movq %r10, TDX_HYPERCALL_r10(%rdi)
> +	movq %r11, TDX_HYPERCALL_r11(%rdi)
> +	movq %r12, TDX_HYPERCALL_r12(%rdi)
> +	movq %r13, TDX_HYPERCALL_r13(%rdi)
> +	movq %r14, TDX_HYPERCALL_r14(%rdi)
> +	movq %r15, TDX_HYPERCALL_r15(%rdi)
> +.Lout:
> +	/* Restore callee-saved GPRs as mandated by the x86_64 ABI */
> +	pop %r12
> +	pop %r13
> +	pop %r14
> +	pop %r15
> +
> +	pop %rbp
> +	ret
> +
> +/* Disable executable stack */
> +.section .note.GNU-stack,"",%progbits
> diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/tdx.c b/tools/testing/selftests/kvm/lib/x86/tdx/tdx.c
> new file mode 100644
> index 000000000000..f417ee75bee2
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx.c
> @@ -0,0 +1,27 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include "tdx/tdcall.h"
> +#include "tdx/tdx.h"
> +
> +uint64_t tdg_vp_vmcall_instruction_io(uint64_t port, uint64_t size,
> +				      uint64_t write, uint64_t *data)
> +{
> +	struct tdx_hypercall_args args = {
> +		.r10 = TDX_HYPERCALL_STANDARD,
> +		.r11 = TDG_VP_VMCALL_INSTRUCTION_IO,
> +		.r12 = size,
> +		.r13 = write,
> +		.r14 = port,
> +	};
> +	uint64_t ret;
> +
> +	if (write)
> +		args.r15 = *data;
> +
> +	ret = __tdx_hypercall(&args, write ? 0 : TDX_HCALL_HAS_OUTPUT);
> +
> +	if (!write)
> +		*data = args.r11;
> +
> +	return ret;
> +}
> diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/test_util.c b/tools/testing/selftests/kvm/lib/x86/tdx/test_util.c
> new file mode 100644
> index 000000000000..7355b213c344
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/lib/x86/tdx/test_util.c
> @@ -0,0 +1,61 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <stdbool.h>
> +#include <stdint.h>
> +#include <stdlib.h>
> +#include <sys/wait.h>
> +#include <unistd.h>
> +
> +#include "kvm_util.h"
> +#include "tdx/tdx.h"
> +#include "tdx/test_util.h"
> +
> +int run_in_new_process(void (*func)(void))
> +{
> +	int wstatus;
> +	pid_t ret;
> +
> +	if (fork() == 0) {
> +		func();
> +		exit(0);
> +	}
> +	ret = wait(&wstatus);
> +	if (ret == -1)
> +		return -1;
> +
> +	if (WIFEXITED(wstatus) && WEXITSTATUS(wstatus))
> +		return -1;
> +	else if (WIFSIGNALED(wstatus))
> +		return -1;
> +
> +	return 0;
> +}
> +
> +bool is_tdx_enabled(void)
> +{
> +	return !!(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_TDX_VM));
> +}
> +
> +void tdx_test_success(void)
> +{
> +	uint64_t code = 0;
> +
> +	tdg_vp_vmcall_instruction_io(TDX_TEST_SUCCESS_PORT, TDX_TEST_SUCCESS_SIZE,
> +				     PORT_WRITE, &code);
> +}
> +
> +/*
> + * Assert that tdx_test_success() was called in the guest.
> + */
> +void tdx_test_assert_success(struct kvm_vcpu *vcpu)
> +{
> +	TEST_ASSERT((vcpu->run->exit_reason == KVM_EXIT_IO) &&
> +		    (vcpu->run->io.port == TDX_TEST_SUCCESS_PORT) &&
> +		    (vcpu->run->io.size == TDX_TEST_SUCCESS_SIZE) &&
> +		    (vcpu->run->io.direction == PORT_WRITE),
> +		    "Unexpected exit values while waiting for test completion: %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);
> +}
> diff --git a/tools/testing/selftests/kvm/x86/tdx_vm_test.c b/tools/testing/selftests/kvm/x86/tdx_vm_test.c
> new file mode 100644
> index 000000000000..fdb7c40065a6
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/x86/tdx_vm_test.c
> @@ -0,0 +1,47 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <signal.h>
> +
> +#include "kvm_util.h"
> +#include "tdx/tdx_util.h"
> +#include "tdx/test_util.h"
> +#include "test_util.h"
> +
> +static void guest_code_lifecycle(void)
> +{
> +	tdx_test_success();
> +}
> +
> +static void verify_td_lifecycle(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_code_lifecycle);
> +	td_finalize(vm);
> +
> +	printf("Verifying TD lifecycle:\n");
> +
> +	vcpu_run(vcpu);
> +	tdx_test_assert_success(vcpu);
> +
> +	kvm_vm_free(vm);
> +	printf("\t ... PASSED\n");
> +}
> +
> +int main(int argc, char **argv)
> +{
> +	ksft_print_header();
> +
> +	if (!is_tdx_enabled())
> +		ksft_exit_skip("TDX is not supported by the KVM. Exiting.\n");
> +
> +	ksft_set_plan(1);
> +	ksft_test_result(!run_in_new_process(&verify_td_lifecycle),
> +			 "verify_td_lifecycle\n");
> +
> +	ksft_finished();
> +	return 0;
> +}