KVM: selftests: Add library support for interacting with SNP

Extend the SEV library to include support for SNP ioctl() wrappers,
which aid in launching and interacting with a SEV-SNP guest.

Signed-off-by: Pratik R. Sampat <prsampat@amd.com>
Link: https://lore.kernel.org/r/20250305230000.231025-8-prsampat@amd.com
[sean: use BIT()]
Signed-off-by: Sean Christopherson <seanjc@google.com>

Author: pratiksampat

arch/x86/include/uapi/asm/kvm.h

@@ -845,6 +845,7 @@ struct kvm_sev_snp_launch_start {
 };
 
 /* Kept in sync with firmware values for simplicity. */
+#define KVM_SEV_PAGE_TYPE_INVALID		0x0
 #define KVM_SEV_SNP_PAGE_TYPE_NORMAL		0x1
 #define KVM_SEV_SNP_PAGE_TYPE_ZERO		0x3
 #define KVM_SEV_SNP_PAGE_TYPE_UNMEASURED	0x4

tools/arch/x86/include/uapi/asm/kvm.h

@@ -841,6 +841,7 @@ struct kvm_sev_snp_launch_start {
 };
 
 /* Kept in sync with firmware values for simplicity. */
+#define KVM_SEV_PAGE_TYPE_INVALID		0x0
 #define KVM_SEV_SNP_PAGE_TYPE_NORMAL		0x1
 #define KVM_SEV_SNP_PAGE_TYPE_ZERO		0x3
 #define KVM_SEV_SNP_PAGE_TYPE_UNMEASURED	0x4

tools/testing/selftests/kvm/include/x86/sev.h

@@ -25,6 +25,10 @@ enum sev_guest_state {
 #define SEV_POLICY_NO_DBG	(1UL << 0)
 #define SEV_POLICY_ES		(1UL << 2)
 
+#define SNP_POLICY_SMT		(1ULL << 16)
+#define SNP_POLICY_RSVD_MBO	(1ULL << 17)
+#define SNP_POLICY_DBG		(1ULL << 19)
+
 #define GHCB_MSR_TERM_REQ	0x100
 
 static inline bool is_sev_snp_vm(struct kvm_vm *vm)
@@ -45,13 +49,26 @@ static inline bool is_sev_vm(struct kvm_vm *vm)
 void sev_vm_launch(struct kvm_vm *vm, uint32_t policy);
 void sev_vm_launch_measure(struct kvm_vm *vm, uint8_t *measurement);
 void sev_vm_launch_finish(struct kvm_vm *vm);
+void snp_vm_launch_start(struct kvm_vm *vm, uint64_t policy);
+void snp_vm_launch_update(struct kvm_vm *vm);
+void snp_vm_launch_finish(struct kvm_vm *vm);
 
 struct kvm_vm *vm_sev_create_with_one_vcpu(uint32_t type, void *guest_code,
 					   struct kvm_vcpu **cpu);
-void vm_sev_launch(struct kvm_vm *vm, uint32_t policy, uint8_t *measurement);
+void vm_sev_launch(struct kvm_vm *vm, uint64_t policy, uint8_t *measurement);
 
 kvm_static_assert(SEV_RET_SUCCESS == 0);
 
+/*
+ * A SEV-SNP VM requires the policy reserved bit to always be set.
+ * The SMT policy bit is also required to be set based on SMT being
+ * available and active on the system.
+ */
+static inline u64 snp_default_policy(void)
+{
+	return SNP_POLICY_RSVD_MBO | (is_smt_on() ? SNP_POLICY_SMT : 0);
+}
+
 /*
  * The KVM_MEMORY_ENCRYPT_OP uAPI is utter garbage and takes an "unsigned long"
  * instead of a proper struct.  The size of the parameter is embedded in the
@@ -85,6 +102,7 @@ kvm_static_assert(SEV_RET_SUCCESS == 0);
 
 void sev_vm_init(struct kvm_vm *vm);
 void sev_es_vm_init(struct kvm_vm *vm);
+void snp_vm_init(struct kvm_vm *vm);
 
 static inline void vmgexit(void)
 {
@@ -113,4 +131,17 @@ static inline void sev_launch_update_data(struct kvm_vm *vm, vm_paddr_t gpa,
 	vm_sev_ioctl(vm, KVM_SEV_LAUNCH_UPDATE_DATA, &update_data);
 }
 
+static inline void snp_launch_update_data(struct kvm_vm *vm, vm_paddr_t gpa,
+					  uint64_t hva, uint64_t size, uint8_t type)
+{
+	struct kvm_sev_snp_launch_update update_data = {
+		.uaddr = hva,
+		.gfn_start = gpa >> PAGE_SHIFT,
+		.len = size,
+		.type = type,
+	};
+
+	vm_sev_ioctl(vm, KVM_SEV_SNP_LAUNCH_UPDATE, &update_data);
+}
+
 #endif /* SELFTEST_KVM_SEV_H */

tools/testing/selftests/kvm/lib/x86/sev.c

@@ -14,7 +14,8 @@
  * and find the first range, but that's correct because the condition
  * expression would cause us to quit the loop.
  */
-static void encrypt_region(struct kvm_vm *vm, struct userspace_mem_region *region)
+static void encrypt_region(struct kvm_vm *vm, struct userspace_mem_region *region,
+			   uint8_t page_type, bool private)
 {
 	const struct sparsebit *protected_phy_pages = region->protected_phy_pages;
 	const vm_paddr_t gpa_base = region->region.guest_phys_addr;
@@ -24,13 +25,23 @@ static void encrypt_region(struct kvm_vm *vm, struct userspace_mem_region *regio
 	if (!sparsebit_any_set(protected_phy_pages))
 		return;
 
-	sev_register_encrypted_memory(vm, region);
+	if (!is_sev_snp_vm(vm))
+		sev_register_encrypted_memory(vm, region);
 
 	sparsebit_for_each_set_range(protected_phy_pages, i, j) {
 		const uint64_t size = (j - i + 1) * vm->page_size;
 		const uint64_t offset = (i - lowest_page_in_region) * vm->page_size;
 
-		sev_launch_update_data(vm, gpa_base + offset, size);
+		if (private)
+			vm_mem_set_private(vm, gpa_base + offset, size);
+
+		if (is_sev_snp_vm(vm))
+			snp_launch_update_data(vm, gpa_base + offset,
+					       (uint64_t)addr_gpa2hva(vm, gpa_base + offset),
+					       size, page_type);
+		else
+			sev_launch_update_data(vm, gpa_base + offset, size);
+
 	}
 }
 
@@ -60,6 +71,14 @@ void sev_es_vm_init(struct kvm_vm *vm)
 	}
 }
 
+void snp_vm_init(struct kvm_vm *vm)
+{
+	struct kvm_sev_init init = { 0 };
+
+	TEST_ASSERT_EQ(vm->type, KVM_X86_SNP_VM);
+	vm_sev_ioctl(vm, KVM_SEV_INIT2, &init);
+}
+
 void sev_vm_launch(struct kvm_vm *vm, uint32_t policy)
 {
 	struct kvm_sev_launch_start launch_start = {
@@ -76,7 +95,7 @@ void sev_vm_launch(struct kvm_vm *vm, uint32_t policy)
 	TEST_ASSERT_EQ(status.state, SEV_GUEST_STATE_LAUNCH_UPDATE);
 
 	hash_for_each(vm->regions.slot_hash, ctr, region, slot_node)
-		encrypt_region(vm, region);
+		encrypt_region(vm, region, KVM_SEV_PAGE_TYPE_INVALID, false);
 
 	if (policy & SEV_POLICY_ES)
 		vm_sev_ioctl(vm, KVM_SEV_LAUNCH_UPDATE_VMSA, NULL);
@@ -112,6 +131,33 @@ void sev_vm_launch_finish(struct kvm_vm *vm)
 	TEST_ASSERT_EQ(status.state, SEV_GUEST_STATE_RUNNING);
 }
 
+void snp_vm_launch_start(struct kvm_vm *vm, uint64_t policy)
+{
+	struct kvm_sev_snp_launch_start launch_start = {
+		.policy = policy,
+	};
+
+	vm_sev_ioctl(vm, KVM_SEV_SNP_LAUNCH_START, &launch_start);
+}
+
+void snp_vm_launch_update(struct kvm_vm *vm)
+{
+	struct userspace_mem_region *region;
+	int ctr;
+
+	hash_for_each(vm->regions.slot_hash, ctr, region, slot_node)
+		encrypt_region(vm, region, KVM_SEV_SNP_PAGE_TYPE_NORMAL, true);
+
+	vm->arch.is_pt_protected = true;
+}
+
+void snp_vm_launch_finish(struct kvm_vm *vm)
+{
+	struct kvm_sev_snp_launch_finish launch_finish = { 0 };
+
+	vm_sev_ioctl(vm, KVM_SEV_SNP_LAUNCH_FINISH, &launch_finish);
+}
+
 struct kvm_vm *vm_sev_create_with_one_vcpu(uint32_t type, void *guest_code,
 					   struct kvm_vcpu **cpu)
 {
@@ -128,8 +174,20 @@ struct kvm_vm *vm_sev_create_with_one_vcpu(uint32_t type, void *guest_code,
 	return vm;
 }
 
-void vm_sev_launch(struct kvm_vm *vm, uint32_t policy, uint8_t *measurement)
+void vm_sev_launch(struct kvm_vm *vm, uint64_t policy, uint8_t *measurement)
 {
+	if (is_sev_snp_vm(vm)) {
+		vm_enable_cap(vm, KVM_CAP_EXIT_HYPERCALL, BIT(KVM_HC_MAP_GPA_RANGE));
+
+		snp_vm_launch_start(vm, policy);
+
+		snp_vm_launch_update(vm);
+
+		snp_vm_launch_finish(vm);
+
+		return;
+	}
+
 	sev_vm_launch(vm, policy);
 
 	if (!measurement)