[PATCH v11 10/21] KVM: selftests: Set up TDX boot parameters region

Sagi Shahar
2025-09-25T17:29:16Z

Allocate memory for TDX boot parameters and define the utility functions
necessary to fill this memory with the boot parameters.

Co-developed-by: Ackerley Tng <ackerleytng@google.com>
Signed-off-by: Ackerley Tng <ackerleytng@google.com>
Signed-off-by: Sagi Shahar <sagis@google.com>

---------------------------------------------

Changes from v10:
* Removed code for setting up X86_CR4_OSXMMEXCPT bit. At least for now
it is not needed and the test pass without it.
---
.../selftests/kvm/include/x86/tdx/tdx_util.h | 4 ++
.../selftests/kvm/lib/x86/tdx/tdx_util.c | 72 +++++++++++++++++++
2 files changed, 76 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
index ec05bcd59145..dafdc7e46abe 100644
--- a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
+++ b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
@@ -12,5 +12,9 @@ static inline bool is_tdx_vm(struct kvm_vm *vm)
}

void vm_tdx_setup_boot_code_region(struct kvm_vm *vm);
+void vm_tdx_setup_boot_parameters_region(struct kvm_vm *vm, uint32_t nr_runnable_vcpus);
+void vm_tdx_load_common_boot_parameters(struct kvm_vm *vm);
+void vm_tdx_load_vcpu_boot_parameters(struct kvm_vm *vm, struct kvm_vcpu *vcpu);
+void vm_tdx_set_vcpu_entry_point(struct kvm_vcpu *vcpu, void *guest_code);

#endif // SELFTESTS_TDX_TDX_UTIL_H
diff --git a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
index a1cf12de9d56..f3b69923e928 100644
--- a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
+++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
@@ -5,10 +5,12 @@
#include "kvm_util.h"
#include "processor.h"
#include "tdx/td_boot.h"
+#include "tdx/td_boot_asm.h"
#include "tdx/tdx_util.h"

/* Arbitrarily selected to avoid overlaps with anything else */
#define TD_BOOT_CODE_SLOT 20
+#define TD_BOOT_PARAMETERS_SLOT 21

#define X86_RESET_VECTOR 0xfffffff0ul
#define X86_RESET_VECTOR_SIZE 16
@@ -52,3 +54,73 @@ void vm_tdx_setup_boot_code_region(struct kvm_vm *vm)
hva[1] = 256 - 2 - TD_BOOT_CODE_SIZE;
hva[2] = 0xcc;
}
+
+void vm_tdx_setup_boot_parameters_region(struct kvm_vm *vm, uint32_t nr_runnable_vcpus)
+{
+ size_t boot_params_size =
+ sizeof(struct td_boot_parameters) +
+ nr_runnable_vcpus * sizeof(struct td_per_vcpu_parameters);
+ int npages = DIV_ROUND_UP(boot_params_size, PAGE_SIZE);
+ vm_paddr_t gpa;
+
+ vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
+ TD_BOOT_PARAMETERS_GPA,
+ TD_BOOT_PARAMETERS_SLOT, npages,
+ KVM_MEM_GUEST_MEMFD);
+ gpa = vm_phy_pages_alloc(vm, npages, TD_BOOT_PARAMETERS_GPA, TD_BOOT_PARAMETERS_SLOT);
+ TEST_ASSERT(gpa == TD_BOOT_PARAMETERS_GPA, "Failed vm_phy_pages_alloc\n");
+
+ virt_map(vm, TD_BOOT_PARAMETERS_GPA, TD_BOOT_PARAMETERS_GPA, npages);
+}
+
+void vm_tdx_load_common_boot_parameters(struct kvm_vm *vm)
+{
+ struct td_boot_parameters *params =
+ addr_gpa2hva(vm, TD_BOOT_PARAMETERS_GPA);
+ uint32_t cr4;
+
+ TEST_ASSERT_EQ(vm->mode, VM_MODE_PXXV48_4K);
+
+ cr4 = kvm_get_default_cr4();
+
+ /* TDX spec 11.6.2: CR4 bit MCE is fixed to 1 */
+ cr4 |= X86_CR4_MCE;
+
+ /* TDX spec 11.6.2: CR4 bit VMXE and SMXE are fixed to 0 */
+ cr4 &= ~(X86_CR4_VMXE | X86_CR4_SMXE);
+
+ /* Set parameters! */
+ params->cr0 = kvm_get_default_cr0();
+ params->cr3 = vm->pgd;
+ params->cr4 = cr4;
+ params->idtr.base = vm->arch.idt;
+ params->idtr.limit = kvm_get_default_idt_limit();
+ params->gdtr.base = vm->arch.gdt;
+ params->gdtr.limit = kvm_get_default_gdt_limit();
+
+ TEST_ASSERT(params->cr0 != 0, "cr0 should not be 0");
+ TEST_ASSERT(params->cr3 != 0, "cr3 should not be 0");
+ TEST_ASSERT(params->cr4 != 0, "cr4 should not be 0");
+ TEST_ASSERT(params->gdtr.base != 0, "gdt base address should not be 0");
+ TEST_ASSERT(params->idtr.base != 0, "idt base address should not be 0");
+}
+
+void vm_tdx_load_vcpu_boot_parameters(struct kvm_vm *vm, struct kvm_vcpu *vcpu)
+{
+ struct td_boot_parameters *params =
+ addr_gpa2hva(vm, TD_BOOT_PARAMETERS_GPA);
+ struct td_per_vcpu_parameters *vcpu_params =
+ &params->per_vcpu[vcpu->id];
+
+ vcpu_params->esp_gva = kvm_allocate_vcpu_stack(vm);
+}
+
+void vm_tdx_set_vcpu_entry_point(struct kvm_vcpu *vcpu, void *guest_code)
+{
+ struct td_boot_parameters *params =
+ addr_gpa2hva(vcpu->vm, TD_BOOT_PARAMETERS_GPA);
+ struct td_per_vcpu_parameters *vcpu_params =
+ &params->per_vcpu[vcpu->id];
+
+ vcpu_params->guest_code = (uint64_t)guest_code;
+}
--
2.51.0.536.g15c5d4f767-goog