Re: [RFC PATCH v5 08/29] KVM: selftests: TDX: Add TDX lifecycle test

From: Zhang, Dongsheng X
Date: Thu Mar 21 2024 - 19:20:59 EST

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On 12/12/2023 12:46 PM, Sagi Shahar wrote:
> From: Erdem Aktas <erdemaktas@xxxxxxxxxx>
>
> Adding a test to verify TDX lifecycle by creating a TD and running a
> dummy TDG.VP.VMCALL <Instruction.IO> inside it.
>
> Signed-off-by: Erdem Aktas <erdemaktas@xxxxxxxxxx>
> Signed-off-by: Ryan Afranji <afranji@xxxxxxxxxx>
> Signed-off-by: Sagi Shahar <sagis@xxxxxxxxxx>
> Co-developed-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
> Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
> ---
> tools/testing/selftests/kvm/Makefile | 4 +
> .../selftests/kvm/include/x86_64/tdx/tdcall.h | 35 ++++++++
> .../selftests/kvm/include/x86_64/tdx/tdx.h | 12 +++
> .../kvm/include/x86_64/tdx/test_util.h | 52 +++++++++++
> .../selftests/kvm/lib/x86_64/tdx/tdcall.S | 90 +++++++++++++++++++
> .../selftests/kvm/lib/x86_64/tdx/tdx.c | 27 ++++++
> .../selftests/kvm/lib/x86_64/tdx/tdx_util.c | 1 +
> .../selftests/kvm/lib/x86_64/tdx/test_util.c | 34 +++++++
> .../selftests/kvm/x86_64/tdx_vm_tests.c | 45 ++++++++++
> 9 files changed, 300 insertions(+)
> create mode 100644 tools/testing/selftests/kvm/include/x86_64/tdx/tdcall.h
> create mode 100644 tools/testing/selftests/kvm/include/x86_64/tdx/tdx.h
> create mode 100644 tools/testing/selftests/kvm/include/x86_64/tdx/test_util.h
> create mode 100644 tools/testing/selftests/kvm/lib/x86_64/tdx/tdcall.S
> create mode 100644 tools/testing/selftests/kvm/lib/x86_64/tdx/tdx.c
> create mode 100644 tools/testing/selftests/kvm/lib/x86_64/tdx/test_util.c
> create mode 100644 tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
>
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index a35150ab855f..80d4a50eeb9f 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -52,6 +52,9 @@ LIBKVM_x86_64 += lib/x86_64/vmx.c
> LIBKVM_x86_64 += lib/x86_64/sev.c
> LIBKVM_x86_64 += lib/x86_64/tdx/tdx_util.c
> LIBKVM_x86_64 += lib/x86_64/tdx/td_boot.S
> +LIBKVM_x86_64 += lib/x86_64/tdx/tdcall.S
> +LIBKVM_x86_64 += lib/x86_64/tdx/tdx.c
> +LIBKVM_x86_64 += lib/x86_64/tdx/test_util.c
>
> LIBKVM_aarch64 += lib/aarch64/gic.c
> LIBKVM_aarch64 += lib/aarch64/gic_v3.c
> @@ -152,6 +155,7 @@ TEST_GEN_PROGS_x86_64 += set_memory_region_test
> TEST_GEN_PROGS_x86_64 += steal_time
> TEST_GEN_PROGS_x86_64 += kvm_binary_stats_test
> TEST_GEN_PROGS_x86_64 += system_counter_offset_test
> +TEST_GEN_PROGS_x86_64 += x86_64/tdx_vm_tests
>
> # Compiled outputs used by test targets
> TEST_GEN_PROGS_EXTENDED_x86_64 += x86_64/nx_huge_pages_test
> diff --git a/tools/testing/selftests/kvm/include/x86_64/tdx/tdcall.h b/tools/testing/selftests/kvm/include/x86_64/tdx/tdcall.h
> new file mode 100644
> index 000000000000..78001bfec9c8
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/include/x86_64/tdx/tdcall.h
> @@ -0,0 +1,35 @@
> +/* 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 TDG_VP_VMCALL_INSTRUCTION_IO_READ 0
> +#define TDG_VP_VMCALL_INSTRUCTION_IO_WRITE 1

Nit:
Probably we can define the following instead in test_util.c?
/* Port I/O direction */
#define PORT_READ 0
#define PORT_WRITE 1

Then use them in place of TDG_VP_VMCALL_INSTRUCTION_IO_READ/TDG_VP_VMCALL_INSTRUCTION_IO_WRITE?
which are too long

> +
> +#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_64/tdx/tdx.h b/tools/testing/selftests/kvm/include/x86_64/tdx/tdx.h
> new file mode 100644
> index 000000000000..a7161efe4ee2
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/include/x86_64/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

Nit:
arch/x86/include/uapi/asm/vmx.h already exports the following define:
#define EXIT_REASON_IO_INSTRUCTION 30

Linux kernel example (arch/x86/coco/tdx/tdx.c):
static bool handle_in(struct pt_regs *regs, int size, int port)
{
struct tdx_module_args args = {
.r10 = TDX_HYPERCALL_STANDARD,
.r11 = hcall_func(EXIT_REASON_IO_INSTRUCTION),
.r12 = size,
.r13 = PORT_READ,
.r14 = port,
};

So just like the kernel, here we can also use EXIT_REASON_IO_INSTRUCTION in place of TDG_VP_VMCALL_INSTRUCTION_IO,
just need to do a '#include "vmx.h"' or '#include <asm/vmx.h>' to bring in the define

> +
> +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_64/tdx/test_util.h b/tools/testing/selftests/kvm/include/x86_64/tdx/test_util.h
> new file mode 100644
> index 000000000000..b570b6d978ff
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/include/x86_64/tdx/test_util.h
> @@ -0,0 +1,52 @@
> +/* 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
> +
> +/**
> + * Assert that tdx_test_success() was called in the guest.
> + */
> +#define TDX_TEST_ASSERT_SUCCESS(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 == \
> + TDG_VP_VMCALL_INSTRUCTION_IO_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))
> +
> +/**
> + * Run a test in a new process.
> + *
> + * There might be multiple tests we are running and if one test fails, it will
> + * prevent the subsequent tests to run due to how tests are failing with
> + * TEST_ASSERT function. The run_in_new_process function 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.
> + */
> +void 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);
> +
> +#endif // SELFTEST_TDX_TEST_UTIL_H
> diff --git a/tools/testing/selftests/kvm/lib/x86_64/tdx/tdcall.S b/tools/testing/selftests/kvm/lib/x86_64/tdx/tdcall.S
> new file mode 100644
> index 000000000000..df9c1ed4bb2d
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/lib/x86_64/tdx/tdcall.S
> @@ -0,0 +1,90 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/* Adapted from arch/x86/coco/tdx/tdcall.S */
> +
> +#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) */
> +
> +/*
> + * 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
> +
> +#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 )
> +
> +.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_64/tdx/tdx.c b/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx.c
> new file mode 100644
> index 000000000000..c2414523487a
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/lib/x86_64/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)
> +{
> + uint64_t ret;
> + struct tdx_hypercall_args args = {
> + .r10 = TDX_HYPERCALL_STANDARD,
> + .r11 = TDG_VP_VMCALL_INSTRUCTION_IO,
> + .r12 = size,
> + .r13 = write,
> + .r14 = port,
> + };
> +
> + 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_64/tdx/tdx_util.c b/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx_util.c
> index 063ff486fb86..b302060049d5 100644
> --- a/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx_util.c
> +++ b/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx_util.c
> @@ -224,6 +224,7 @@ static void tdx_enable_capabilities(struct kvm_vm *vm)
> KVM_X2APIC_API_USE_32BIT_IDS |
> KVM_X2APIC_API_DISABLE_BROADCAST_QUIRK);
> vm_enable_cap(vm, KVM_CAP_SPLIT_IRQCHIP, 24);
> + vm_enable_cap(vm, KVM_CAP_MAX_VCPUS, 512);
> }
>
> static void tdx_configure_memory_encryption(struct kvm_vm *vm)
> diff --git a/tools/testing/selftests/kvm/lib/x86_64/tdx/test_util.c b/tools/testing/selftests/kvm/lib/x86_64/tdx/test_util.c
> new file mode 100644
> index 000000000000..6905d0ca3877
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/lib/x86_64/tdx/test_util.c
> @@ -0,0 +1,34 @@
> +// 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_base.h"
> +#include "tdx/tdx.h"
> +#include "tdx/test_util.h"
> +
> +void run_in_new_process(void (*func)(void))
> +{
> + if (fork() == 0) {
> + func();
> + exit(0);
> + }
> + wait(NULL);
> +}
> +
> +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,
> + TDG_VP_VMCALL_INSTRUCTION_IO_WRITE, &code);
> +}
> diff --git a/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
> new file mode 100644
> index 000000000000..a18d1c9d6026
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/x86_64/tdx_vm_tests.c
> @@ -0,0 +1,45 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <signal.h>
> +#include "kvm_util_base.h"
> +#include "tdx/tdx_util.h"
> +#include "tdx/test_util.h"
> +#include "test_util.h"
> +
> +void guest_code_lifecycle(void)
> +{
> + tdx_test_success();
> +}
> +
> +void verify_td_lifecycle(void)
> +{
> + struct kvm_vm *vm;
> + struct kvm_vcpu *vcpu;
> +
> + 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");
> +}

Nit:
All the functions used locally inside tdx_vm_tests.c can be declared static:
static void guest_code_lifecycle(void)
static void verify_td_lifecycle(void)

> +
> +int main(int argc, char **argv)
> +{
> + setbuf(stdout, NULL);
> +
> + if (!is_tdx_enabled()) {
> + print_skip("TDX is not supported by the KVM");
> + exit(KSFT_SKIP);
> + }
> +
> + run_in_new_process(&verify_td_lifecycle);
> +
> + return 0;
> +}

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