linux-kernel - [PATCH v4 07/28] KVM: selftests: TDX: Update load_td_memory_region for VM memory backed by guest memfd

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Message-ID: <20230725220132.2310657-8-afranji@google.com>
Date:   Tue, 25 Jul 2023 22:01:00 +0000
From:   Ryan Afranji <afranji@...gle.com>
To:     linux-kselftest@...r.kernel.org
Cc:     pbonzini@...hat.com, seanjc@...gle.com, isaku.yamahata@...el.com,
        sagis@...gle.com, erdemaktas@...gle.com, afranji@...gle.com,
        runanwang@...gle.com, shuah@...nel.org, drjones@...hat.com,
        maz@...nel.org, bgardon@...gle.com, jmattson@...gle.com,
        dmatlack@...gle.com, peterx@...hat.com, oupton@...gle.com,
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        xiaoyao.li@...el.com, pgonda@...gle.com, eesposit@...hat.com,
        borntraeger@...ibm.com, eric.auger@...hat.com,
        wangyanan55@...wei.com, aaronlewis@...gle.com, vkuznets@...hat.com,
        pshier@...gle.com, axelrasmussen@...gle.com,
        zhenzhong.duan@...el.com, maciej.szmigiero@...cle.com,
        like.xu@...ux.intel.com, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, ackerleytng@...gle.com
Subject: [PATCH v4 07/28] KVM: selftests: TDX: Update load_td_memory_region
 for VM memory backed by guest memfd

From: Ackerley Tng <ackerleytng@...gle.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@...gle.com>
Change-Id: I43a5a444d5d2b5bf0d6750f6ef82c16e3d7d755e
Signed-off-by: Ryan Afranji <afranji@...gle.com>
---
 .../selftests/kvm/lib/x86_64/tdx/tdx_util.c   | 41 +++++++++++++++----
 1 file changed, 32 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 95c6fb263583..c30801f4f759 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
@@ -199,6 +199,21 @@ 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)
+{
+	vm_set_memory_attributes(vm, region->region.guest_phys_addr,
+				 region->region.memory_size,
+				 KVM_MEMORY_ATTRIBUTE_PRIVATE);
+}
+
 /*
  * TD creation/setup/finalization
  */
@@ -383,30 +398,38 @@ static void load_td_memory_region(struct kvm_vm *vm,
 	if (!sparsebit_any_set(pages))
 		return;
 
+
+	if (region->region.gmem_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.gmem_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.gmem_fd == -1)
+			munmap(source_addr, size_to_load);
 	}
 }
 
-- 
2.41.0.487.g6d72f3e995-goog