On 8/8/2025 4:16 AM, Sagi Shahar wrote:
> From: Roger Wang <runanwang@xxxxxxxxxx>
>
> Adds a test for TDG.VP.INFO.
>
> Introduce __tdx_module_call() that does needed shuffling from function
> parameters to registers used by the TDCALL instruction that is used by the
> guest to communicate with the TDX module. The first function parameter is
> the leaf number indicating which guest side function should be run, for
> example, TDG.VP.INFO.
>
> The guest uses new __tdx_module_call() to call TDG.VP.INFO to obtain TDX
> TD execution environment information from the TDX module. All returned
> registers are passed back to the host that verifies values for
> correctness.
>
> Co-developed-by: Sagi Shahar <sagis@xxxxxxxxxx>
> Signed-off-by: Sagi Shahar <sagis@xxxxxxxxxx>
> Signed-off-by: Roger Wang <runanwang@xxxxxxxxxx>
> Signed-off-by: Sagi Shahar <sagis@xxxxxxxxxx>
Duplicated SOB. Please change the order according to submmitting-patches.rst.
And check the whole series for such SOB issue.
> ---
> .../selftests/kvm/include/x86/tdx/tdcall.h | 19 +++
> .../selftests/kvm/include/x86/tdx/tdx.h | 5 +
> .../selftests/kvm/lib/x86/tdx/tdcall.S | 68 +++++++++
> tools/testing/selftests/kvm/lib/x86/tdx/tdx.c | 27 ++++
> tools/testing/selftests/kvm/x86/tdx_vm_test.c | 133 +++++++++++++++++-
> 5 files changed, 251 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/kvm/include/x86/tdx/tdcall.h b/tools/testing/selftests/kvm/include/x86/tdx/tdcall.h
> index e7440f7fe259..ab1a97a82fa9 100644
> --- a/tools/testing/selftests/kvm/include/x86/tdx/tdcall.h
> +++ b/tools/testing/selftests/kvm/include/x86/tdx/tdcall.h
> @@ -32,4 +32,23 @@ struct tdx_hypercall_args {
> /* Used to request services from the VMM */
> u64 __tdx_hypercall(struct tdx_hypercall_args *args, unsigned long flags);
>
> +/*
> + * Used to gather the output registers values of the TDCALL and SEAMCALL
This series only uses this struct to gather values for TDCALL. Please remove
the "SEAMCALL" for accuracy.
> + * instructions when requesting services from the TDX module.
> + *
> + * This is a software only structure and not part of the TDX module/VMM ABI.
> + */
> +struct tdx_module_output {
> + u64 rcx;
> + u64 rdx;
> + u64 r8;
> + u64 r9;
> + u64 r10;
> + u64 r11;
> +};
> +
> +/* Used to communicate with the TDX module */
> +u64 __tdx_module_call(u64 fn, u64 rcx, u64 rdx, u64 r8, u64 r9,
> + struct tdx_module_output *out);
> +
> #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
> index 060158cb046b..801ca879664e 100644
> --- a/tools/testing/selftests/kvm/include/x86/tdx/tdx.h
> +++ b/tools/testing/selftests/kvm/include/x86/tdx/tdx.h
> @@ -6,6 +6,8 @@
>
> #include "kvm_util.h"
>
> +#define TDG_VP_INFO 1
> +
> #define TDG_VP_VMCALL_GET_TD_VM_CALL_INFO 0x10000
> #define TDG_VP_VMCALL_REPORT_FATAL_ERROR 0x10003
>
> @@ -31,5 +33,8 @@ uint64_t tdg_vp_vmcall_ve_request_mmio_write(uint64_t address, uint64_t size,
> uint64_t tdg_vp_vmcall_instruction_cpuid(uint32_t eax, uint32_t ecx,
> uint32_t *ret_eax, uint32_t *ret_ebx,
> uint32_t *ret_ecx, uint32_t *ret_edx);
> +uint64_t tdg_vp_info(uint64_t *rcx, uint64_t *rdx,
> + uint64_t *r8, uint64_t *r9,
> + uint64_t *r10, uint64_t *r11);
>
> #endif // SELFTEST_TDX_TDX_H
> diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/tdcall.S b/tools/testing/selftests/kvm/lib/x86/tdx/tdcall.S
> index b10769d1d557..c393a0fb35be 100644
> --- a/tools/testing/selftests/kvm/lib/x86/tdx/tdcall.S
> +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdcall.S
> @@ -91,5 +91,73 @@ __tdx_hypercall:
> pop %rbp
> ret
>
> +#define TDX_MODULE_rcx 0 /* offsetof(struct tdx_module_output, rcx) */
> +#define TDX_MODULE_rdx 8 /* offsetof(struct tdx_module_output, rdx) */
> +#define TDX_MODULE_r8 16 /* offsetof(struct tdx_module_output, r8) */
> +#define TDX_MODULE_r9 24 /* offsetof(struct tdx_module_output, r9) */
> +#define TDX_MODULE_r10 32 /* offsetof(struct tdx_module_output, r10) */
> +#define TDX_MODULE_r11 40 /* offsetof(struct tdx_module_output, r11) */
> +
> +.globl __tdx_module_call
> +.type __tdx_module_call, @function
> +__tdx_module_call:
> + /* Set up stack frame */
> + push %rbp
> + movq %rsp, %rbp
> +
> + /* Callee-saved, so preserve it */
> + push %r12
> +
> + /*
> + * Push output pointer to stack.
> + * After the operation, it will be fetched into R12 register.
> + */
> + push %r9
> +
> + /* Mangle function call ABI into TDCALL/SEAMCALL ABI: */
> + /* Move Leaf ID to RAX */
> + mov %rdi, %rax
> + /* Move input 4 to R9 */
> + mov %r8, %r9
> + /* Move input 3 to R8 */
> + mov %rcx, %r8
> + /* Move input 1 to RCX */
> + mov %rsi, %rcx
> + /* Leave input param 2 in RDX */
> +
> + tdcall
> +
> + /*
> + * Fetch output pointer from stack to R12 (It is used
> + * as temporary storage)
> + */
> + pop %r12
> +
> + /*
> + * Since this macro can be invoked with NULL as an output pointer,
> + * check if caller provided an output struct before storing output
> + * registers.
> + *
> + * Update output registers, even if the call failed (RAX != 0).
> + * Other registers may contain details of the failure.
> + */
> + test %r12, %r12
> + jz .Lno_output_struct
> +
> + /* Copy result registers to output struct: */
> + movq %rcx, TDX_MODULE_rcx(%r12)
> + movq %rdx, TDX_MODULE_rdx(%r12)
> + movq %r8, TDX_MODULE_r8(%r12)
> + movq %r9, TDX_MODULE_r9(%r12)
> + movq %r10, TDX_MODULE_r10(%r12)
> + movq %r11, TDX_MODULE_r11(%r12)
> +
> +.Lno_output_struct:
> + /* Restore the state of R12 register */
> + pop %r12
> +
> + 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
> index fb391483d2fa..ab6fd3d7ae4b 100644
> --- a/tools/testing/selftests/kvm/lib/x86/tdx/tdx.c
> +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx.c
> @@ -162,3 +162,30 @@ uint64_t tdg_vp_vmcall_instruction_cpuid(uint32_t eax, uint32_t ecx,
>
> return ret;
> }
> +
> +uint64_t tdg_vp_info(uint64_t *rcx, uint64_t *rdx,
> + uint64_t *r8, uint64_t *r9,
> + uint64_t *r10, uint64_t *r11)
> +{
> + struct tdx_module_output out;
> + uint64_t ret;
> +
> + memset(&out, 0, sizeof(struct tdx_module_output));
> +
> + ret = __tdx_module_call(TDG_VP_INFO, 0, 0, 0, 0, &out);
> +
> + if (rcx)
> + *rcx = out.rcx;
> + if (rdx)
> + *rdx = out.rdx;
> + if (r8)
> + *r8 = out.r8;
> + if (r9)
> + *r9 = out.r9;
> + if (r10)
> + *r10 = out.r10;
> + if (r11)
> + *r11 = out.r11;
> +
> + return ret;
> +}
> diff --git a/tools/testing/selftests/kvm/x86/tdx_vm_test.c b/tools/testing/selftests/kvm/x86/tdx_vm_test.c
> index b6ef0348746c..82acc17a66ab 100644
> --- a/tools/testing/selftests/kvm/x86/tdx_vm_test.c
> +++ b/tools/testing/selftests/kvm/x86/tdx_vm_test.c
> @@ -1038,6 +1038,135 @@ void verify_host_reading_private_mem(void)
> printf("\t ... PASSED\n");
> }
>
> +/*
> + * Do a TDG.VP.INFO call from the guest
> + */
> +void guest_tdcall_vp_info(void)
> +{
> + uint64_t rcx, rdx, r8, r9, r10, r11;
> + uint64_t err;
> +
> + err = tdg_vp_info(&rcx, &rdx, &r8, &r9, &r10, &r11);
> + tdx_assert_error(err);
> +
> + /* return values to user space host */
> + err = tdx_test_report_64bit_to_user_space(rcx);
> + tdx_assert_error(err);
> +
> + err = tdx_test_report_64bit_to_user_space(rdx);
> + tdx_assert_error(err);
> +
> + err = tdx_test_report_64bit_to_user_space(r8);
> + tdx_assert_error(err);
> +
> + err = tdx_test_report_64bit_to_user_space(r9);
> + tdx_assert_error(err);
> +
> + err = tdx_test_report_64bit_to_user_space(r10);
> + tdx_assert_error(err);
> +
> + err = tdx_test_report_64bit_to_user_space(r11);
> + tdx_assert_error(err);
> +
> + tdx_test_success();
> +}
> +
> +/*
> + * TDG.VP.INFO call from the guest. Verify the right values are returned
> + */
> +void verify_tdcall_vp_info(void)
> +{
> + const struct kvm_cpuid_entry2 *cpuid_entry;
> + uint32_t ret_num_vcpus, ret_max_vcpus;
> + uint64_t rcx, rdx, r8, r9, r10, r11;
> + const int num_vcpus = 2;
> + struct kvm_vcpu *vcpus[num_vcpus];
> + uint64_t attributes;
> + struct kvm_vm *vm;
> + int gpa_bits = -1;
> + uint32_t i;
> +
> + vm = td_create();
> +
> +#define TDX_TDPARAM_ATTR_SEPT_VE_DISABLE_BIT BIT(28)
> + /* Setting attributes parameter used by TDH.MNG.INIT to 0x10000000 */
> + attributes = TDX_TDPARAM_ATTR_SEPT_VE_DISABLE_BIT;
> +
> + td_initialize(vm, VM_MEM_SRC_ANONYMOUS, attributes);
> +
> + for (i = 0; i < num_vcpus; i++)
> + vcpus[i] = td_vcpu_add(vm, i, guest_tdcall_vp_info);
> +
> + td_finalize(vm);
> +
> + printf("Verifying TDG.VP.INFO call:\n");
> +
> + /* Get KVM CPUIDs for reference */
> +
> + for (i = 0; i < num_vcpus; i++) {
> + struct kvm_vcpu *vcpu = vcpus[i];
> +
> + cpuid_entry = vcpu_get_cpuid_entry(vcpu, 0x80000008);
> + TEST_ASSERT(cpuid_entry, "CPUID entry missing\n");
> + gpa_bits = (cpuid_entry->eax & GENMASK(23, 16)) >> 16;
> + TEST_ASSERT_EQ((1UL << (gpa_bits - 1)), tdx_s_bit);
> +
> + /* Wait for guest to report rcx value */
> + tdx_run(vcpu);
> + rcx = tdx_test_read_64bit_report_from_guest(vcpu);
> +
> + /* Wait for guest to report rdx value */
> + tdx_run(vcpu);
> + rdx = tdx_test_read_64bit_report_from_guest(vcpu);
> +
> + /* Wait for guest to report r8 value */
> + tdx_run(vcpu);
> + r8 = tdx_test_read_64bit_report_from_guest(vcpu);
> +
> + /* Wait for guest to report r9 value */
> + tdx_run(vcpu);
> + r9 = tdx_test_read_64bit_report_from_guest(vcpu);
> +
> + /* Wait for guest to report r10 value */
> + tdx_run(vcpu);
> + r10 = tdx_test_read_64bit_report_from_guest(vcpu);
> +
> + /* Wait for guest to report r11 value */
> + tdx_run(vcpu);
> + r11 = tdx_test_read_64bit_report_from_guest(vcpu);
> +
> + ret_num_vcpus = r8 & 0xFFFFFFFF;
> + ret_max_vcpus = (r8 >> 32) & 0xFFFFFFFF;
> +
> + /* first bits 5:0 of rcx represent the GPAW */
> + TEST_ASSERT_EQ(rcx & 0x3F, gpa_bits);
> + /* next 63:6 bits of rcx is reserved and must be 0 */
> + TEST_ASSERT_EQ(rcx >> 6, 0);
> + TEST_ASSERT_EQ(rdx, attributes);
> + TEST_ASSERT_EQ(ret_num_vcpus, num_vcpus);
> + TEST_ASSERT_EQ(ret_max_vcpus, vm_check_cap(vm, KVM_CAP_MAX_VCPUS));
> + /* VCPU_INDEX = i */
> + TEST_ASSERT_EQ(r9, i);
The format for r9 is
- 31:0
VCPU_INDEX
- 62:32
Reserved to 0
Maybe add the check for reserved bits as other registers
