Re: [PATCH v9 14/19] KVM: selftests: Add helpers to init TDX memory and finalize VM

[Yan Zhao <yan.y.zhao@intel.com>]

On Wed, Aug 20, 2025 at 09:29:07PM -0700, 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      | 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
> 
>