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Date:   Fri, 15 Jul 2022 12:29:49 -0700
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Subject: [RFC V1 03/10] KVM: selftests: add hooks for managing encrypted guest memory
From:   Peter Gonda <pgonda@google.com>
To:     kvm@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, marcorr@google.com,
        seanjc@google.com, michael.roth@amd.com, thomas.lendacky@amd.com,
        joro@8bytes.org, mizhang@google.com, pbonzini@redhat.com,
        Peter Gonda <pgonda@google.com>
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From: 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.

Reviewed-by: Mingwei Zhang <mizhang@google.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Peter Gonda <pgonda@google.com>

---
 .../selftests/kvm/include/kvm_util_base.h     | 17 ++++++
 tools/testing/selftests/kvm/lib/kvm_util.c    | 52 +++++++++++++++++--
 2 files changed, 66 insertions(+), 3 deletions(-)

diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index b78e3c7a2566..3acb1552942b 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -32,6 +32,7 @@ typedef uint64_t vm_vaddr_t; /* Virtual Machine (Guest) virtual address */
 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;
@@ -61,6 +62,14 @@ 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;
@@ -84,6 +93,7 @@ struct kvm_vm {
 	vm_vaddr_t idt;
 	vm_vaddr_t handlers;
 	uint32_t dirty_ring_size;
+	struct vm_memcrypt memcrypt;
 
 	/* Cache of information for binary stats interface */
 	int stats_fd;
@@ -820,4 +830,11 @@ static inline int __vm_disable_nx_huge_pages(struct kvm_vm *vm)
 	return __vm_enable_cap(vm, KVM_CAP_VM_DISABLE_NX_HUGE_PAGES, 0);
 }
 
+void vm_set_memory_encryption(struct kvm_vm *vm, bool enc_by_default, bool has_enc_bit,
+			      uint8_t enc_bit);
+
+const struct sparsebit *vm_get_encrypted_phy_pages(struct kvm_vm *vm, int slot,
+						   vm_paddr_t *gpa_start,
+						   uint64_t *size);
+
 #endif /* SELFTEST_KVM_UTIL_BASE_H */
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index b07c372b9b37..6f96d1c51f75 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -529,6 +529,7 @@ static void __vm_mem_region_delete(struct kvm_vm *vm,
 	vm_ioctl(vm, KVM_SET_USER_MEMORY_REGION, &region->region);
 
 	sparsebit_free(&region->unused_phy_pages);
+	sparsebit_free(&region->encrypted_phy_pages);
 	ret = munmap(region->mmap_start, region->mmap_size);
 	TEST_ASSERT(!ret, __KVM_SYSCALL_ERROR("munmap()", ret));
 
@@ -869,6 +870,7 @@ 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;
@@ -1084,6 +1086,7 @@ struct kvm_vcpu *__vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id)
  *   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
  *
@@ -1095,8 +1098,9 @@ struct kvm_vcpu *__vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpu_id)
  * 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;
@@ -1129,12 +1133,22 @@ 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);
+	}
 
 	return base * vm->page_size;
 }
 
+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, num, paddr_min, memslot,
+				   vm->memcrypt.enc_by_default);
+}
+
 vm_paddr_t vm_phy_page_alloc(struct kvm_vm *vm, vm_paddr_t paddr_min,
 			     uint32_t memslot)
 {
@@ -1718,6 +1732,10 @@ 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);
@@ -1966,3 +1984,31 @@ void __vm_get_stat(struct kvm_vm *vm, const char *stat_name, uint64_t *data,
 		break;
 	}
 }
+
+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;
+}
+
+const 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;
+
+	if (!vm->memcrypt.enabled)
+		return NULL;
+
+	region = memslot2region(vm, slot);
+	if (!region)
+		return NULL;
+
+	*size = region->region.memory_size;
+	*gpa_start = region->region.guest_phys_addr;
+
+	return region->encrypted_phy_pages;
+}
-- 
2.37.0.170.g444d1eabd0-goog