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

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@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;

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);