[RFC 02/16] KVM: selftests: add hooks for managing encrypted guest memory

[Michael Roth <michael.roth@amd.com>]

VM implementations that make use of encrypted memory need a way to
configure things like the encryption/shared bit position for page
table handling, the default encryption policy for internal allocations
made by the core library, and a way to fetch the list/bitmap of
encrypted pages to do the actual memory encryption. Add an interface to
configure these parameters. Also introduce a sparsebit map to track
allocations/mappings that should be treated as encrypted, and provide
a way for VM implementations to retrieve it to handle operations
related memory encryption.

Signed-off-by: Michael Roth <michael.roth@amd.com>
---
 .../testing/selftests/kvm/include/kvm_util.h  |  6 ++
 tools/testing/selftests/kvm/lib/kvm_util.c    | 63 +++++++++++++++++--
 .../selftests/kvm/lib/kvm_util_internal.h     | 10 +++
 3 files changed, 75 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 010b59b13917..f417de80596c 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -348,6 +348,12 @@ int vm_create_device(struct kvm_vm *vm, struct kvm_create_device *cd);
 
 void assert_on_unhandled_exception(struct kvm_vm *vm, uint32_t vcpuid);
 
+void vm_set_memory_encryption(struct kvm_vm *vm, bool enc_by_default, bool has_enc_bit,
+			      uint8_t enc_bit);
+struct sparsebit *vm_get_encrypted_phy_pages(struct kvm_vm *vm, int slot,
+					     vm_paddr_t *gpa_start,
+					     uint64_t *size);
+
 /* Common ucalls */
 enum {
 	UCALL_NONE,
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 92f59adddebe..c58f930dedd2 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -631,6 +631,7 @@ static void __vm_mem_region_delete(struct kvm_vm *vm,
 		    "rc: %i errno: %i", ret, errno);
 
 	sparsebit_free(&region->unused_phy_pages);
+	sparsebit_free(&region->encrypted_phy_pages);
 	ret = munmap(region->mmap_start, region->mmap_size);
 	TEST_ASSERT(ret == 0, "munmap failed, rc: %i errno: %i", ret, errno);
 
@@ -924,6 +925,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
 	}
 
 	region->unused_phy_pages = sparsebit_alloc();
+	region->encrypted_phy_pages = sparsebit_alloc();
 	sparsebit_set_num(region->unused_phy_pages,
 		guest_paddr >> vm->page_shift, npages);
 	region->region.slot = slot;
@@ -1153,6 +1155,7 @@ void vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpuid)
  *   num - number of pages
  *   paddr_min - Physical address minimum
  *   memslot - Memory region to allocate page from
+ *   encrypt - Whether to treat the pages as encrypted
  *
  * Output Args: None
  *
@@ -1164,11 +1167,13 @@ void vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpuid)
  * and their base address is returned. A TEST_ASSERT failure occurs if
  * not enough pages are available at or above paddr_min.
  */
-vm_paddr_t vm_phy_pages_alloc(struct kvm_vm *vm, size_t num,
-			      vm_paddr_t paddr_min, uint32_t memslot)
+static vm_paddr_t
+_vm_phy_pages_alloc(struct kvm_vm *vm, size_t num, vm_paddr_t paddr_min,
+		    uint32_t memslot, bool encrypt)
 {
 	struct userspace_mem_region *region;
 	sparsebit_idx_t pg, base;
+	vm_paddr_t gpa;
 
 	TEST_ASSERT(num > 0, "Must allocate at least one page");
 
@@ -1198,10 +1203,25 @@ vm_paddr_t vm_phy_pages_alloc(struct kvm_vm *vm, size_t num,
 		abort();
 	}
 
-	for (pg = base; pg < base + num; ++pg)
+	for (pg = base; pg < base + num; ++pg) {
 		sparsebit_clear(region->unused_phy_pages, pg);
+		if (encrypt)
+			sparsebit_set(region->encrypted_phy_pages, pg);
+	}
+
+	gpa = base * vm->page_size;
 
-	return base * vm->page_size;
+	if (encrypt && vm->memcrypt.has_enc_bit)
+		gpa |= (1ULL << vm->memcrypt.enc_bit);
+
+	return gpa;
+}
+
+vm_paddr_t vm_phy_pages_alloc(struct kvm_vm *vm, size_t num,
+			      vm_paddr_t paddr_min, uint32_t memslot)
+{
+	return _vm_phy_pages_alloc(vm, 1, paddr_min, memslot,
+				   vm->memcrypt.enc_by_default);
 }
 
 vm_paddr_t vm_phy_page_alloc(struct kvm_vm *vm, vm_paddr_t paddr_min,
@@ -2146,6 +2166,10 @@ void vm_dump(FILE *stream, struct kvm_vm *vm, uint8_t indent)
 			region->host_mem);
 		fprintf(stream, "%*sunused_phy_pages: ", indent + 2, "");
 		sparsebit_dump(stream, region->unused_phy_pages, 0);
+		if (vm->memcrypt.enabled) {
+			fprintf(stream, "%*sencrypted_phy_pages: ", indent + 2, "");
+			sparsebit_dump(stream, region->encrypted_phy_pages, 0);
+		}
 	}
 	fprintf(stream, "%*sMapped Virtual Pages:\n", indent, "");
 	sparsebit_dump(stream, vm->vpages_mapped, indent + 2);
@@ -2343,3 +2367,34 @@ int vcpu_get_stats_fd(struct kvm_vm *vm, uint32_t vcpuid)
 
 	return ioctl(vcpu->fd, KVM_GET_STATS_FD, NULL);
 }
+
+void vm_set_memory_encryption(struct kvm_vm *vm, bool enc_by_default, bool has_enc_bit,
+			      uint8_t enc_bit)
+{
+	vm->memcrypt.enabled = true;
+	vm->memcrypt.enc_by_default = enc_by_default;
+	vm->memcrypt.has_enc_bit = has_enc_bit;
+	vm->memcrypt.enc_bit = enc_bit;
+}
+
+struct sparsebit *
+vm_get_encrypted_phy_pages(struct kvm_vm *vm, int slot, vm_paddr_t *gpa_start,
+			   uint64_t *size)
+{
+	struct userspace_mem_region *region;
+	struct sparsebit *encrypted_phy_pages;
+
+	if (!vm->memcrypt.enabled)
+		return NULL;
+
+	region = memslot2region(vm, slot);
+	if (!region)
+		return NULL;
+
+	encrypted_phy_pages = sparsebit_alloc();
+	sparsebit_copy(encrypted_phy_pages, region->encrypted_phy_pages);
+	*size = region->region.memory_size;
+	*gpa_start = region->region.guest_phys_addr;
+
+	return encrypted_phy_pages;
+}
diff --git a/tools/testing/selftests/kvm/lib/kvm_util_internal.h b/tools/testing/selftests/kvm/lib/kvm_util_internal.h
index a03febc24ba6..99ccab86115c 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util_internal.h
+++ b/tools/testing/selftests/kvm/lib/kvm_util_internal.h
@@ -16,6 +16,7 @@
 struct userspace_mem_region {
 	struct kvm_userspace_memory_region region;
 	struct sparsebit *unused_phy_pages;
+	struct sparsebit *encrypted_phy_pages;
 	int fd;
 	off_t offset;
 	void *host_mem;
@@ -44,6 +45,14 @@ struct userspace_mem_regions {
 	DECLARE_HASHTABLE(slot_hash, 9);
 };
 
+/* Memory encryption policy/configuration. */
+struct vm_memcrypt {
+	bool enabled;
+	int8_t enc_by_default;
+	bool has_enc_bit;
+	int8_t enc_bit;
+};
+
 struct kvm_vm {
 	int mode;
 	unsigned long type;
@@ -67,6 +76,7 @@ struct kvm_vm {
 	vm_vaddr_t idt;
 	vm_vaddr_t handlers;
 	uint32_t dirty_ring_size;
+	struct vm_memcrypt memcrypt;
 };
 
 struct vcpu *vcpu_find(struct kvm_vm *vm, uint32_t vcpuid);
-- 
2.25.1