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

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On 10/5/21 4:44 PM, Michael Roth wrote:
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@xxxxxxx>
---
  .../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;


For readability, it's probably better to adopt a standard naming convention for structures, members and  functions ?  For example,

        encrypted_phy_pages    ->     enc_phy_pages

        struct vm_memcrypt  {    ->    struct vm_mem_enc {

        struct vm_memcrypt memcrypt    ->    struct vm_mem_enc  mem_enc

        vm_get_encrypted_phy_pages()    -> vm_get_enc_phy_pages



  };
struct vcpu *vcpu_find(struct kvm_vm *vm, uint32_t vcpuid);



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