On Wed, Aug 20, 2025 at 09:29:07PM -0700, Sagi Shahar wrote:
> From: Ackerley Tng <[email protected]>
>
> TDX protected memory needs to be measured and encrypted before it can be
> used by the guest. Traverse the VM's memory regions and initialize all
> the protected ranges by calling KVM_TDX_INIT_MEM_REGION.
>
> Once all the memory is initialized, the VM can be finalized by calling
> KVM_TDX_FINALIZE_VM.
>
> Signed-off-by: Ackerley Tng <[email protected]>
> Co-developed-by: Erdem Aktas <[email protected]>
> Signed-off-by: Erdem Aktas <[email protected]>
> Co-developed-by: Sagi Shahar <[email protected]>
> Signed-off-by: Sagi Shahar <[email protected]>
> ---
> .../selftests/kvm/include/x86/tdx/tdx_util.h | 2 +
> .../selftests/kvm/lib/x86/tdx/tdx_util.c | 97 +++++++++++++++++++
> 2 files changed, 99 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 a2509959c7ce..2467b6c35557 100644
> --- a/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
> +++ b/tools/testing/selftests/kvm/include/x86/tdx/tdx_util.h
> @@ -71,4 +71,6 @@ 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);
>
> +void vm_tdx_finalize(struct kvm_vm *vm);
> +
> #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 d8eab99d9333..4024587ed3c2 100644
> --- a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> @@ -274,3 +274,100 @@ void vm_tdx_init_vm(struct kvm_vm *vm, uint64_t
> attributes)
>
> free(init_vm);
> }
> +
> +static void tdx_init_mem_region(struct kvm_vm *vm, void *source_pages,
> + uint64_t gpa, uint64_t size)
> +{
> + uint32_t metadata = KVM_TDX_MEASURE_MEMORY_REGION;
> + struct kvm_tdx_init_mem_region mem_region = {
> + .source_addr = (uint64_t)source_pages,
> + .gpa = gpa,
> + .nr_pages = size / PAGE_SIZE,
> + };
> + struct kvm_vcpu *vcpu;
> +
> + vcpu = list_first_entry_or_null(&vm->vcpus, struct kvm_vcpu, list);
> +
> + TEST_ASSERT((mem_region.nr_pages > 0) &&
> + ((mem_region.nr_pages * PAGE_SIZE) == size),
> + "Cannot add partial pages to the guest memory.\n");
> + TEST_ASSERT(((uint64_t)source_pages & (PAGE_SIZE - 1)) == 0,
> + "Source memory buffer is not page aligned\n");
> + vm_tdx_vcpu_ioctl(vcpu, KVM_TDX_INIT_MEM_REGION, metadata, &mem_region);
> +}
> +
> +static void tdx_init_pages(struct kvm_vm *vm, void *hva, uint64_t gpa,
> + uint64_t size)
> +{
> + void *scratch_page = calloc(1, PAGE_SIZE);
> + uint64_t nr_pages = size / PAGE_SIZE;
> + int i;
> +
> + TEST_ASSERT(scratch_page,
> + "Could not allocate memory for loading memory region");
> +
> + for (i = 0; i < nr_pages; i++) {
> + memcpy(scratch_page, hva, PAGE_SIZE);
> +
> + tdx_init_mem_region(vm, scratch_page, gpa, PAGE_SIZE);
> +
> + hva += PAGE_SIZE;
> + gpa += PAGE_SIZE;
> + }
> +
> + free(scratch_page);
> +}
> +
> +static void load_td_private_memory(struct kvm_vm *vm)
> +{
> + struct userspace_mem_region *region;
> + int ctr;
> +
> + hash_for_each(vm->regions.slot_hash, ctr, region, slot_node) {
> + const struct sparsebit *protected_pages =
> region->protected_phy_pages;
> + const vm_paddr_t gpa_base = region->region.guest_phys_addr;
> + const uint64_t hva_base = region->region.userspace_addr;
> + const sparsebit_idx_t lowest_page_in_region = gpa_base >>
> vm->page_shift;
> +
> + sparsebit_idx_t i;
> + sparsebit_idx_t j;
> +
> + if (!sparsebit_any_set(protected_pages))
> + continue;
> +
> + sparsebit_for_each_set_range(protected_pages, i, j) {
> + const uint64_t size_to_load = (j - i + 1) *
> vm->page_size;
> + const uint64_t offset =
> + (i - lowest_page_in_region) * vm->page_size;
> + const uint64_t hva = hva_base + offset;
> + const uint64_t gpa = gpa_base + offset;
> +
> + vm_set_memory_attributes(vm, gpa, size_to_load,
> + KVM_MEMORY_ATTRIBUTE_PRIVATE);
> +
> + /*
> + * Here, memory is being loaded from hva to gpa. If the
> memory
> + * mapped to hva is also used to back gpa, then a copy
> has to be
> + * made just for loading, since KVM_TDX_INIT_MEM_REGION
> ioctl
> + * cannot encrypt memory in place.
> + *
> + * To determine if memory mapped to hva is also used to
> back
> + * gpa, use a heuristic:
> + *
> + * If this memslot has guest_memfd, then this memslot
> should
> + * have memory backed from two sources: hva for shared
> memory
> + * and gpa will be backed by guest_memfd.
> + */
> + if (region->region.guest_memfd == -1)
Why to pass !guest_memfd region to tdx_init_mem_region()?
> + tdx_init_pages(vm, (void *)hva, gpa,
> size_to_load);
> + else
> + tdx_init_mem_region(vm, (void *)hva, gpa,
> size_to_load);
> + }
> + }
> +}
> +
> +void vm_tdx_finalize(struct kvm_vm *vm)
> +{
> + load_td_private_memory(vm);
> + vm_tdx_vm_ioctl(vm, KVM_TDX_FINALIZE_VM, 0, NULL);
> +}
> --
> 2.51.0.rc1.193.gad69d77794-goog
>
>
