With guest_memfd in-place conversion, the memory region can be set as shared, eliminating the need for dual-backed memory.
By setting the region to shared initially, the KVM selftest framework can populate the mmap()-ed guest_memfd memory just like any standard memory provider. For CoCo VMs, pages that need to be private are explicitly set to private before executing the VM. Signed-off-by: Lisa Wang <[email protected]> --- tools/testing/selftests/kvm/lib/kvm_util.c | 20 ++++++++++++++------ tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c | 6 +++++- 2 files changed, 19 insertions(+), 7 deletions(-) diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index 7625908caf21..f474664b5d92 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -494,8 +494,10 @@ struct kvm_vm *__vm_create(struct vm_shape shape, u32 nr_runnable_vcpus, u64 nr_pages = vm_nr_pages_required(shape.mode, nr_runnable_vcpus, nr_extra_pages); struct userspace_mem_region *slot0; + u64 gmem_flags = 0; struct kvm_vm *vm; - int i, flags; + int flags = 0; + int i; kvm_set_files_rlimit(nr_runnable_vcpus); @@ -505,14 +507,20 @@ struct kvm_vm *__vm_create(struct vm_shape shape, u32 nr_runnable_vcpus, vm = ____vm_create(shape); /* - * Force GUEST_MEMFD for the primary memory region if necessary, e.g. - * for CoCo VMs that require GUEST_MEMFD backed private memory. + * Force GUEST_MEMFD for the primary memory region if necessary, and + * initialize it as shared if in-place conversion is supported, so the + * selftest framework can populate it exactly like other memory + * providers. */ - flags = 0; - if (is_guest_memfd_required(shape)) + if (is_guest_memfd_required(shape)) { flags |= KVM_MEM_GUEST_MEMFD; + if (kvm_has_gmem_attributes) + gmem_flags |= GUEST_MEMFD_FLAG_INIT_SHARED | + GUEST_MEMFD_FLAG_MMAP; + } - vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, 0, 0, nr_pages, flags); + vm_mem_add(vm, VM_MEM_SRC_ANONYMOUS, 0, 0, nr_pages, flags, + -1, 0, gmem_flags); for (i = 0; i < NR_MEM_REGIONS; i++) vm->memslots[i] = 0; 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 e348507a6be8..40ee9b1951c2 100644 --- a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c @@ -23,6 +23,8 @@ void tdx_vm_setup_boot_code_region(struct kvm_vm *vm) gpa_t gpa; u8 *hva; + if (kvm_has_gmem_attributes) + gmem_flags |= GUEST_MEMFD_FLAG_INIT_SHARED | GUEST_MEMFD_FLAG_MMAP; vm_mem_add(vm, VM_MEM_SRC_SHMEM, alloc_gpa, TD_BOOT_CODE_SLOT, nr_pages, KVM_MEM_GUEST_MEMFD, -1, 0, gmem_flags); @@ -44,9 +46,11 @@ void tdx_vm_setup_boot_parameters_region(struct kvm_vm *vm, u32 nr_runnable_vcpu 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); - const u64 gmem_flags = 0; + u64 gmem_flags = 0; gpa_t gpa; + if (kvm_has_gmem_attributes) + gmem_flags |= GUEST_MEMFD_FLAG_INIT_SHARED | GUEST_MEMFD_FLAG_MMAP; vm_mem_add(vm, VM_MEM_SRC_SHMEM, TD_BOOT_PARAMETERS_GPA, TD_BOOT_PARAMETERS_SLOT, npages, KVM_MEM_GUEST_MEMFD, -1, 0, gmem_flags); -- 2.56.0.rc1.315.gc6ed9934b7-goog
