[PATCH v13 11/22] KVM: selftests: Set up TDX boot parameters region

From: Lisa Wang

Date: Thu May 21 2026 - 19:27:41 EST


From: Sagi Shahar <sagis@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Ackerley Tng <ackerleytng@xxxxxxxxxx>
Signed-off-by: Sagi Shahar <sagis@xxxxxxxxxx>
Signed-off-by: Lisa Wang <wyihan@xxxxxxxxxx>
---
.../selftests/kvm/include/x86/tdx/tdx_util.h | 2 +
tools/testing/selftests/kvm/lib/x86/processor.c | 2 +
tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c | 56 ++++++++++++++++++++++
3 files changed, 60 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 d66ea7bc85f9..9660ea9d2f31 100644
--- a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
+++ b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
@@ -41,5 +41,7 @@ static inline bool is_tdx_vm(struct kvm_vm *vm)

void tdx_init_vm(struct kvm_vm *vm, u64 attributes);
void tdx_vm_setup_boot_code_region(struct kvm_vm *vm);
+void tdx_vm_setup_boot_parameters_region(struct kvm_vm *vm, u32 nr_runnable_vcpus);
+void tdx_vm_load_common_boot_parameters(struct kvm_vm *vm);

#endif /* SELFTESTS_TDX_TDX_UTIL_H */
diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c b/tools/testing/selftests/kvm/lib/x86/processor.c
index dfabdfd17976..c7c4a37b3170 100644
--- a/tools/testing/selftests/kvm/lib/x86/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86/processor.c
@@ -794,6 +794,8 @@ void kvm_arch_vm_post_create(struct kvm_vm *vm, unsigned int nr_vcpus)
if (is_tdx_vm(vm)) {
tdx_init_vm(vm, 0);
tdx_vm_setup_boot_code_region(vm);
+ tdx_vm_setup_boot_parameters_region(vm, nr_vcpus);
+ tdx_vm_load_common_boot_parameters(vm);
}

r = __vm_ioctl(vm, KVM_GET_TSC_KHZ, NULL);
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 bbfaa9af9c60..b16bf24f3ef1 100644
--- a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
+++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
@@ -3,10 +3,12 @@
#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
@@ -51,6 +53,60 @@ void tdx_vm_setup_boot_code_region(struct kvm_vm *vm)
hva[2] = 0xcc;
}

+void tdx_vm_setup_boot_parameters_region(struct kvm_vm *vm, u32 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);
+ gpa_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 tdx_vm_load_common_boot_parameters(struct kvm_vm *vm)
+{
+ struct td_boot_parameters *params =
+ addr_gpa2hva(vm, TD_BOOT_PARAMETERS_GPA);
+ u32 cr4;
+
+ TEST_ASSERT_EQ(vm->mode, VM_MODE_PXXVYY_4K);
+
+ cr4 = kvm_get_default_cr4();
+ if (vm->mmu.pgtable_levels == 5)
+ cr4 |= X86_CR4_LA57;
+
+ /* 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();
+ TEST_ASSERT(vm->mmu.pgd < (1ULL << 32),
+ "PGD must be within 32-bit address space for 32-bit boot code");
+ params->cr3 = vm->mmu.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");
+}
+
static struct kvm_tdx_capabilities *tdx_read_capabilities(struct kvm_vm *vm)
{
struct kvm_tdx_capabilities *tdx_cap = NULL;

--
2.54.0.746.g67dd491aae-goog