On 10/2/2026 3:37 AM, Lisa Wang wrote: > 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);
This is common for both TDX and SNP, does it break SNP? > 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); >
