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Sampat" , Reinette Chatre , Ira Weiny , linux-kernel@vger.kernel.org, kvm@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Thu, Aug 07, 2025, Sagi Shahar wrote: > From: Ackerley Tng > > If guest memory is backed by restricted memfd > > + UPM is being used, hence encrypted memory region has to be > registered > + Can avoid making a copy of guest memory before getting TDX to > initialize the memory region > > Signed-off-by: Ackerley Tng > Signed-off-by: Sagi Shahar > --- > .../selftests/kvm/lib/x86/tdx/tdx_util.c | 38 +++++++++++++++---- > 1 file changed, 30 insertions(+), 8 deletions(-) > > 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 bb074af4a476..e2bf9766dc03 100644 > --- a/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c > +++ b/tools/testing/selftests/kvm/lib/x86/tdx/tdx_util.c > @@ -324,6 +324,21 @@ static void tdx_td_finalize_mr(struct kvm_vm *vm) > tdx_ioctl(vm->fd, KVM_TDX_FINALIZE_VM, 0, NULL); > } > > +/* > + * Other ioctls > + */ > + > +/* > + * Register a memory region that may contain encrypted data in KVM. > + */ Drop these comments. > +static void register_encrypted_memory_region(struct kvm_vm *vm, > + struct userspace_mem_region *region) This is a comically bad helper. Any person that is at all familiar with KVM's CoCo support, or that simply reads KVM's documentation, will expect this to invoke KVM_MEMORY_ENCRYPT_REG_REGION. And this is obviously doing much more than "registering" an encrypted region. Not to mention this helper doesn't need to exist; it has _one_ caller, and the code is quite self-explanatory. > +{ > + vm_set_memory_attributes(vm, region->region.guest_phys_addr, > + region->region.memory_size, > + KVM_MEMORY_ATTRIBUTE_PRIVATE); > +} > + > /* > * TD creation/setup/finalization > */ > @@ -459,28 +474,35 @@ static void load_td_memory_region(struct kvm_vm *vm, > if (!sparsebit_any_set(pages)) > return; > > + if (region->region.guest_memfd != -1) > + register_encrypted_memory_region(vm, region); > + > sparsebit_for_each_set_range(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; > - void *source_addr; > + void *source_addr = (void *)hva; > > /* > * KVM_TDX_INIT_MEM_REGION ioctl cannot encrypt memory in place. > * Make a copy if there's only one backing memory source. > */ > - source_addr = mmap(NULL, size_to_load, PROT_READ | PROT_WRITE, > - MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); > - TEST_ASSERT(source_addr, > - "Could not allocate memory for loading memory region"); > - > - memcpy(source_addr, (void *)hva, size_to_load); > + if (region->region.guest_memfd == -1) { Oh, here's the "if". > + source_addr = mmap(NULL, size_to_load, PROT_READ | PROT_WRITE, > + MAP_ANONYMOUS | MAP_PRIVATE, -1, 0); > + TEST_ASSERT(source_addr, > + "Could not allocate memory for loading memory region"); > + > + memcpy(source_addr, (void *)hva, size_to_load); > + memset((void *)hva, 0, size_to_load); > + } > > tdx_init_mem_region(vm, source_addr, gpa, size_to_load); > > - munmap(source_addr, size_to_load); > + if (region->region.guest_memfd == -1) > + munmap(source_addr, size_to_load); > } > } > > -- > 2.51.0.rc0.155.g4a0f42376b-goog >