Re: [PATCH v10 13/21] KVM: selftests: Add helpers to init TDX memory and finalize VM

[Binbin Wu <binbin.wu@linux.intel.com>]

On 9/4/2025 2:54 PM, Sagi Shahar wrote:
> From: Ackerley Tng <ackerleytng@google.com>
>
> 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 <ackerleytng@google.com>
> Co-developed-by: Erdem Aktas <erdemaktas@google.com>
> Signed-off-by: Erdem Aktas <erdemaktas@google.com>
> Co-developed-by: Sagi Shahar <sagis@google.com>
> Signed-off-by: Sagi Shahar <sagis@google.com>
> ---
>   .../selftests/kvm/include/x86/tdx/tdx_util.h  |  2 +
>   .../selftests/kvm/lib/x86/tdx/tdx_util.c      | 61 +++++++++++++++++++
>   2 files changed, 63 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 1b5c01faf1cd..d5df2de81a75 100644
> --- a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c
> @@ -273,3 +273,64 @@ 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 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;
> +

A spare white line?

> +		sparsebit_idx_t i;
> +		sparsebit_idx_t j;

i and j could be defined in one line.

> +
> +		if (!sparsebit_any_set(protected_pages))
> +			continue;
> +
> +		TEST_ASSERT(region->region.guest_memfd != -1,
> +			    "TD private memory must be backed by guest_memfd");
> +
> +		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);
Nit:
There is a helper vm_mem_set_private() for it.

> +			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);
> +}