[RFC PATCH v3 26/31] KVM: selftests: TDX: Update load_td_memory_region for VM memory backed by restricted memfd

[Ackerley Tng <ackerleytng@google.com>]

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 <ackerleytng@google.com>
---
 .../selftests/kvm/lib/x86_64/tdx/tdx_util.c   | 43 +++++++++++++++----
 1 file changed, 34 insertions(+), 9 deletions(-)

diff --git a/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx_util.c b/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx_util.c
index 4d6615b97770a..77803b7a1d739 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx_util.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/tdx/tdx_util.c
@@ -207,6 +207,23 @@ static void tdx_td_finalizemr(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.
+ */
+static void register_encrypted_memory_region(
+	struct kvm_vm *vm, struct userspace_mem_region *region)
+{
+	struct kvm_enc_region range = {
+		.addr = region->region.guest_phys_addr,
+		.size = region->region.memory_size,
+	};
+	vm_ioctl(vm, KVM_MEMORY_ENCRYPT_REG_REGION, &range);
+}
+
 /*
  * TD creation/setup/finalization
  */
@@ -393,30 +410,38 @@ static void load_td_memory_region(struct kvm_vm *vm,
 	if (!sparsebit_any_set(pages))
 		return;
 
+
+	if (region->region_ext.restricted_fd != -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,
 		 * hence we have to 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_ext.restricted_fd == -1) {
+			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_ext.restricted_fd == -1)
+			munmap(source_addr, size_to_load);
 	}
 }
 
-- 
2.39.0.246.g2a6d74b583-goog