1 files changed, 466 insertions, 38 deletions
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index 55326b1bd247..552653fa18be 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -21,21 +21,33 @@
 
 #define KVM_HOST_S2_FLAGS (KVM_PGTABLE_S2_NOFWB | KVM_PGTABLE_S2_IDMAP)
 
-extern unsigned long hyp_nr_cpus;
-struct host_kvm host_kvm;
+struct host_mmu host_mmu;
 
 static struct hyp_pool host_s2_pool;
 
-const u8 pkvm_hyp_id = 1;
+static DEFINE_PER_CPU(struct pkvm_hyp_vm *, __current_vm);
+#define current_vm (*this_cpu_ptr(&__current_vm))
+
+static void guest_lock_component(struct pkvm_hyp_vm *vm)
+{
+	hyp_spin_lock(&vm->lock);
+	current_vm = vm;
+}
+
+static void guest_unlock_component(struct pkvm_hyp_vm *vm)
+{
+	current_vm = NULL;
+	hyp_spin_unlock(&vm->lock);
+}
 
 static void host_lock_component(void)
 {
-	hyp_spin_lock(&host_kvm.lock);
+	hyp_spin_lock(&host_mmu.lock);
 }
 
 static void host_unlock_component(void)
 {
-	hyp_spin_unlock(&host_kvm.lock);
+	hyp_spin_unlock(&host_mmu.lock);
 }
 
 static void hyp_lock_component(void)
@@ -81,7 +93,7 @@ static void host_s2_put_page(void *addr)
 
 static void host_s2_free_removed_table(void *addr, u32 level)
 {
-	kvm_pgtable_stage2_free_removed(&host_kvm.mm_ops, addr, level);
+	kvm_pgtable_stage2_free_removed(&host_mmu.mm_ops, addr, level);
 }
 
 static int prepare_s2_pool(void *pgt_pool_base)
@@ -95,7 +107,7 @@ static int prepare_s2_pool(void *pgt_pool_base)
 	if (ret)
 		return ret;
 
-	host_kvm.mm_ops = (struct kvm_pgtable_mm_ops) {
+	host_mmu.mm_ops = (struct kvm_pgtable_mm_ops) {
 		.zalloc_pages_exact = host_s2_zalloc_pages_exact,
 		.zalloc_page = host_s2_zalloc_page,
 		.free_removed_table = host_s2_free_removed_table,
@@ -117,7 +129,7 @@ static void prepare_host_vtcr(void)
 	parange = kvm_get_parange(id_aa64mmfr0_el1_sys_val);
 	phys_shift = id_aa64mmfr0_parange_to_phys_shift(parange);
 
-	host_kvm.arch.vtcr = kvm_get_vtcr(id_aa64mmfr0_el1_sys_val,
+	host_mmu.arch.vtcr = kvm_get_vtcr(id_aa64mmfr0_el1_sys_val,
 					  id_aa64mmfr1_el1_sys_val, phys_shift);
 }
 
@@ -125,45 +137,170 @@ static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot pr
 
 int kvm_host_prepare_stage2(void *pgt_pool_base)
 {
-	struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
+	struct kvm_s2_mmu *mmu = &host_mmu.arch.mmu;
 	int ret;
 
 	prepare_host_vtcr();
-	hyp_spin_lock_init(&host_kvm.lock);
-	mmu->arch = &host_kvm.arch;
+	hyp_spin_lock_init(&host_mmu.lock);
+	mmu->arch = &host_mmu.arch;
 
 	ret = prepare_s2_pool(pgt_pool_base);
 	if (ret)
 		return ret;
 
-	ret = __kvm_pgtable_stage2_init(&host_kvm.pgt, mmu,
-					&host_kvm.mm_ops, KVM_HOST_S2_FLAGS,
+	ret = __kvm_pgtable_stage2_init(&host_mmu.pgt, mmu,
+					&host_mmu.mm_ops, KVM_HOST_S2_FLAGS,
 					host_stage2_force_pte_cb);
 	if (ret)
 		return ret;
 
-	mmu->pgd_phys = __hyp_pa(host_kvm.pgt.pgd);
-	mmu->pgt = &host_kvm.pgt;
+	mmu->pgd_phys = __hyp_pa(host_mmu.pgt.pgd);
+	mmu->pgt = &host_mmu.pgt;
 	atomic64_set(&mmu->vmid.id, 0);
 
 	return 0;
 }
 
+static bool guest_stage2_force_pte_cb(u64 addr, u64 end,
+				      enum kvm_pgtable_prot prot)
+{
+	return true;
+}
+
+static void *guest_s2_zalloc_pages_exact(size_t size)
+{
+	void *addr = hyp_alloc_pages(&current_vm->pool, get_order(size));
+
+	WARN_ON(size != (PAGE_SIZE << get_order(size)));
+	hyp_split_page(hyp_virt_to_page(addr));
+
+	return addr;
+}
+
+static void guest_s2_free_pages_exact(void *addr, unsigned long size)
+{
+	u8 order = get_order(size);
+	unsigned int i;
+
+	for (i = 0; i < (1 << order); i++)
+		hyp_put_page(&current_vm->pool, addr + (i * PAGE_SIZE));
+}
+
+static void *guest_s2_zalloc_page(void *mc)
+{
+	struct hyp_page *p;
+	void *addr;
+
+	addr = hyp_alloc_pages(&current_vm->pool, 0);
+	if (addr)
+		return addr;
+
+	addr = pop_hyp_memcache(mc, hyp_phys_to_virt);
+	if (!addr)
+		return addr;
+
+	memset(addr, 0, PAGE_SIZE);
+	p = hyp_virt_to_page(addr);
+	memset(p, 0, sizeof(*p));
+	p->refcount = 1;
+
+	return addr;
+}
+
+static void guest_s2_get_page(void *addr)
+{
+	hyp_get_page(&current_vm->pool, addr);
+}
+
+static void guest_s2_put_page(void *addr)
+{
+	hyp_put_page(&current_vm->pool, addr);
+}
+
+static void clean_dcache_guest_page(void *va, size_t size)
+{
+	__clean_dcache_guest_page(hyp_fixmap_map(__hyp_pa(va)), size);
+	hyp_fixmap_unmap();
+}
+
+static void invalidate_icache_guest_page(void *va, size_t size)
+{
+	__invalidate_icache_guest_page(hyp_fixmap_map(__hyp_pa(va)), size);
+	hyp_fixmap_unmap();
+}
+
+int kvm_guest_prepare_stage2(struct pkvm_hyp_vm *vm, void *pgd)
+{
+	struct kvm_s2_mmu *mmu = &vm->kvm.arch.mmu;
+	unsigned long nr_pages;
+	int ret;
+
+	nr_pages = kvm_pgtable_stage2_pgd_size(vm->kvm.arch.vtcr) >> PAGE_SHIFT;
+	ret = hyp_pool_init(&vm->pool, hyp_virt_to_pfn(pgd), nr_pages, 0);
+	if (ret)
+		return ret;
+
+	hyp_spin_lock_init(&vm->lock);
+	vm->mm_ops = (struct kvm_pgtable_mm_ops) {
+		.zalloc_pages_exact	= guest_s2_zalloc_pages_exact,
+		.free_pages_exact	= guest_s2_free_pages_exact,
+		.zalloc_page		= guest_s2_zalloc_page,
+		.phys_to_virt		= hyp_phys_to_virt,
+		.virt_to_phys		= hyp_virt_to_phys,
+		.page_count		= hyp_page_count,
+		.get_page		= guest_s2_get_page,
+		.put_page		= guest_s2_put_page,
+		.dcache_clean_inval_poc	= clean_dcache_guest_page,
+		.icache_inval_pou	= invalidate_icache_guest_page,
+	};
+
+	guest_lock_component(vm);
+	ret = __kvm_pgtable_stage2_init(mmu->pgt, mmu, &vm->mm_ops, 0,
+					guest_stage2_force_pte_cb);
+	guest_unlock_component(vm);
+	if (ret)
+		return ret;
+
+	vm->kvm.arch.mmu.pgd_phys = __hyp_pa(vm->pgt.pgd);
+
+	return 0;
+}
+
+void reclaim_guest_pages(struct pkvm_hyp_vm *vm, struct kvm_hyp_memcache *mc)
+{
+	void *addr;
+
+	/* Dump all pgtable pages in the hyp_pool */
+	guest_lock_component(vm);
+	kvm_pgtable_stage2_destroy(&vm->pgt);
+	vm->kvm.arch.mmu.pgd_phys = 0ULL;
+	guest_unlock_component(vm);
+
+	/* Drain the hyp_pool into the memcache */
+	addr = hyp_alloc_pages(&vm->pool, 0);
+	while (addr) {
+		memset(hyp_virt_to_page(addr), 0, sizeof(struct hyp_page));
+		push_hyp_memcache(mc, addr, hyp_virt_to_phys);
+		WARN_ON(__pkvm_hyp_donate_host(hyp_virt_to_pfn(addr), 1));
+		addr = hyp_alloc_pages(&vm->pool, 0);
+	}
+}
+
 int __pkvm_prot_finalize(void)
 {
-	struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
+	struct kvm_s2_mmu *mmu = &host_mmu.arch.mmu;
 	struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);
 
 	if (params->hcr_el2 & HCR_VM)
 		return -EPERM;
 
 	params->vttbr = kvm_get_vttbr(mmu);
-	params->vtcr = host_kvm.arch.vtcr;
+	params->vtcr = host_mmu.arch.vtcr;
 	params->hcr_el2 |= HCR_VM;
 	kvm_flush_dcache_to_poc(params, sizeof(*params));
 
 	write_sysreg(params->hcr_el2, hcr_el2);
-	__load_stage2(&host_kvm.arch.mmu, &host_kvm.arch);
+	__load_stage2(&host_mmu.arch.mmu, &host_mmu.arch);
 
 	/*
 	 * Make sure to have an ISB before the TLB maintenance below but only
@@ -181,7 +318,7 @@ int __pkvm_prot_finalize(void)
 
 static int host_stage2_unmap_dev_all(void)
 {
-	struct kvm_pgtable *pgt = &host_kvm.pgt;
+	struct kvm_pgtable *pgt = &host_mmu.pgt;
 	struct memblock_region *reg;
 	u64 addr = 0;
 	int i, ret;
@@ -201,7 +338,7 @@ struct kvm_mem_range {
 	u64 end;
 };
 
-static bool find_mem_range(phys_addr_t addr, struct kvm_mem_range *range)
+static struct memblock_region *find_mem_range(phys_addr_t addr, struct kvm_mem_range *range)
 {
 	int cur, left = 0, right = hyp_memblock_nr;
 	struct memblock_region *reg;
@@ -224,18 +361,28 @@ static bool find_mem_range(phys_addr_t addr, struct kvm_mem_range *range)
 		} else {
 			range->start = reg->base;
 			range->end = end;
-			return true;
+			return reg;
 		}
 	}
 
-	return false;
+	return NULL;
 }
 
 bool addr_is_memory(phys_addr_t phys)
 {
 	struct kvm_mem_range range;
 
-	return find_mem_range(phys, &range);
+	return !!find_mem_range(phys, &range);
+}
+
+static bool addr_is_allowed_memory(phys_addr_t phys)
+{
+	struct memblock_region *reg;
+	struct kvm_mem_range range;
+
+	reg = find_mem_range(phys, &range);
+
+	return reg && !(reg->flags & MEMBLOCK_NOMAP);
 }
 
 static bool is_in_mem_range(u64 addr, struct kvm_mem_range *range)
@@ -256,7 +403,7 @@ static bool range_is_memory(u64 start, u64 end)
 static inline int __host_stage2_idmap(u64 start, u64 end,
 				      enum kvm_pgtable_prot prot)
 {
-	return kvm_pgtable_stage2_map(&host_kvm.pgt, start, end - start, start,
+	return kvm_pgtable_stage2_map(&host_mmu.pgt, start, end - start, start,
 				      prot, &host_s2_pool, 0);
 }
 
@@ -269,7 +416,7 @@ static inline int __host_stage2_idmap(u64 start, u64 end,
 #define host_stage2_try(fn, ...)					\
 	({								\
 		int __ret;						\
-		hyp_assert_lock_held(&host_kvm.lock);			\
+		hyp_assert_lock_held(&host_mmu.lock);			\
 		__ret = fn(__VA_ARGS__);				\
 		if (__ret == -ENOMEM) {					\
 			__ret = host_stage2_unmap_dev_all();		\
@@ -292,8 +439,8 @@ static int host_stage2_adjust_range(u64 addr, struct kvm_mem_range *range)
 	u32 level;
 	int ret;
 
-	hyp_assert_lock_held(&host_kvm.lock);
-	ret = kvm_pgtable_get_leaf(&host_kvm.pgt, addr, &pte, &level);
+	hyp_assert_lock_held(&host_mmu.lock);
+	ret = kvm_pgtable_get_leaf(&host_mmu.pgt, addr, &pte, &level);
 	if (ret)
 		return ret;
 
@@ -325,7 +472,7 @@ int host_stage2_idmap_locked(phys_addr_t addr, u64 size,
 
 int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id)
 {
-	return host_stage2_try(kvm_pgtable_stage2_set_owner, &host_kvm.pgt,
+	return host_stage2_try(kvm_pgtable_stage2_set_owner, &host_mmu.pgt,
 			       addr, size, &host_s2_pool, owner_id);
 }
 
@@ -354,7 +501,7 @@ static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot pr
 static int host_stage2_idmap(u64 addr)
 {
 	struct kvm_mem_range range;
-	bool is_memory = find_mem_range(addr, &range);
+	bool is_memory = !!find_mem_range(addr, &range);
 	enum kvm_pgtable_prot prot;
 	int ret;
 
@@ -386,12 +533,6 @@ void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
 	BUG_ON(ret && ret != -EAGAIN);
 }
 
-/* This corresponds to locking order */
-enum pkvm_component_id {
-	PKVM_ID_HOST,
-	PKVM_ID_HYP,
-};
-
 struct pkvm_mem_transition {
 	u64				nr_pages;
 
@@ -405,6 +546,9 @@ struct pkvm_mem_transition {
 				/* Address in the completer's address space */
 				u64	completer_addr;
 			} host;
+			struct {
+				u64	completer_addr;
+			} hyp;
 		};
 	} initiator;
 
@@ -418,6 +562,10 @@ struct pkvm_mem_share {
 	const enum kvm_pgtable_prot		completer_prot;
 };
 
+struct pkvm_mem_donation {
+	const struct pkvm_mem_transition	tx;
+};
+
 struct check_walk_data {
 	enum pkvm_page_state	desired;
 	enum pkvm_page_state	(*get_page_state)(kvm_pte_t pte);
@@ -428,7 +576,7 @@ static int __check_page_state_visitor(const struct kvm_pgtable_visit_ctx *ctx,
 {
 	struct check_walk_data *d = ctx->arg;
 
-	if (kvm_pte_valid(ctx->old) && !addr_is_memory(kvm_pte_to_phys(ctx->old)))
+	if (kvm_pte_valid(ctx->old) && !addr_is_allowed_memory(kvm_pte_to_phys(ctx->old)))
 		return -EINVAL;
 
 	return d->get_page_state(ctx->old) == d->desired ? 0 : -EPERM;
@@ -462,8 +610,8 @@ static int __host_check_page_state_range(u64 addr, u64 size,
 		.get_page_state	= host_get_page_state,
 	};
 
-	hyp_assert_lock_held(&host_kvm.lock);
-	return check_page_state_range(&host_kvm.pgt, addr, size, &d);
+	hyp_assert_lock_held(&host_mmu.lock);
+	return check_page_state_range(&host_mmu.pgt, addr, size, &d);
 }
 
 static int __host_set_page_state_range(u64 addr, u64 size,
@@ -514,6 +662,46 @@ static int host_initiate_unshare(u64 *completer_addr,
 	return __host_set_page_state_range(addr, size, PKVM_PAGE_OWNED);
 }
 
+static int host_initiate_donation(u64 *completer_addr,
+				  const struct pkvm_mem_transition *tx)
+{
+	u8 owner_id = tx->completer.id;
+	u64 size = tx->nr_pages * PAGE_SIZE;
+
+	*completer_addr = tx->initiator.host.completer_addr;
+	return host_stage2_set_owner_locked(tx->initiator.addr, size, owner_id);
+}
+
+static bool __host_ack_skip_pgtable_check(const struct pkvm_mem_transition *tx)
+{
+	return !(IS_ENABLED(CONFIG_NVHE_EL2_DEBUG) ||
+		 tx->initiator.id != PKVM_ID_HYP);
+}
+
+static int __host_ack_transition(u64 addr, const struct pkvm_mem_transition *tx,
+				 enum pkvm_page_state state)
+{
+	u64 size = tx->nr_pages * PAGE_SIZE;
+
+	if (__host_ack_skip_pgtable_check(tx))
+		return 0;
+
+	return __host_check_page_state_range(addr, size, state);
+}
+
+static int host_ack_donation(u64 addr, const struct pkvm_mem_transition *tx)
+{
+	return __host_ack_transition(addr, tx, PKVM_NOPAGE);
+}
+
+static int host_complete_donation(u64 addr, const struct pkvm_mem_transition *tx)
+{
+	u64 size = tx->nr_pages * PAGE_SIZE;
+	u8 host_id = tx->completer.id;
+
+	return host_stage2_set_owner_locked(addr, size, host_id);
+}
+
 static enum pkvm_page_state hyp_get_page_state(kvm_pte_t pte)
 {
 	if (!kvm_pte_valid(pte))
@@ -534,6 +722,27 @@ static int __hyp_check_page_state_range(u64 addr, u64 size,
 	return check_page_state_range(&pkvm_pgtable, addr, size, &d);
 }
 
+static int hyp_request_donation(u64 *completer_addr,
+				const struct pkvm_mem_transition *tx)
+{
+	u64 size = tx->nr_pages * PAGE_SIZE;
+	u64 addr = tx->initiator.addr;
+
+	*completer_addr = tx->initiator.hyp.completer_addr;
+	return __hyp_check_page_state_range(addr, size, PKVM_PAGE_OWNED);
+}
+
+static int hyp_initiate_donation(u64 *completer_addr,
+				 const struct pkvm_mem_transition *tx)
+{
+	u64 size = tx->nr_pages * PAGE_SIZE;
+	int ret;
+
+	*completer_addr = tx->initiator.hyp.completer_addr;
+	ret = kvm_pgtable_hyp_unmap(&pkvm_pgtable, tx->initiator.addr, size);
+	return (ret != size) ? -EFAULT : 0;
+}
+
 static bool __hyp_ack_skip_pgtable_check(const struct pkvm_mem_transition *tx)
 {
 	return !(IS_ENABLED(CONFIG_NVHE_EL2_DEBUG) ||
@@ -558,6 +767,9 @@ static int hyp_ack_unshare(u64 addr, const struct pkvm_mem_transition *tx)
 {
 	u64 size = tx->nr_pages * PAGE_SIZE;
 
+	if (tx->initiator.id == PKVM_ID_HOST && hyp_page_count((void *)addr))
+		return -EBUSY;
+
 	if (__hyp_ack_skip_pgtable_check(tx))
 		return 0;
 
@@ -565,6 +777,16 @@ static int hyp_ack_unshare(u64 addr, const struct pkvm_mem_transition *tx)
 					    PKVM_PAGE_SHARED_BORROWED);
 }
 
+static int hyp_ack_donation(u64 addr, const struct pkvm_mem_transition *tx)
+{
+	u64 size = tx->nr_pages * PAGE_SIZE;
+
+	if (__hyp_ack_skip_pgtable_check(tx))
+		return 0;
+
+	return __hyp_check_page_state_range(addr, size, PKVM_NOPAGE);
+}
+
 static int hyp_complete_share(u64 addr, const struct pkvm_mem_transition *tx,
 			      enum kvm_pgtable_prot perms)
 {
@@ -583,6 +805,15 @@ static int hyp_complete_unshare(u64 addr, const struct pkvm_mem_transition *tx)
 	return (ret != size) ? -EFAULT : 0;
 }
 
+static int hyp_complete_donation(u64 addr,
+				 const struct pkvm_mem_transition *tx)
+{
+	void *start = (void *)addr, *end = start + (tx->nr_pages * PAGE_SIZE);
+	enum kvm_pgtable_prot prot = pkvm_mkstate(PAGE_HYP, PKVM_PAGE_OWNED);
+
+	return pkvm_create_mappings_locked(start, end, prot);
+}
+
 static int check_share(struct pkvm_mem_share *share)
 {
 	const struct pkvm_mem_transition *tx = &share->tx;
@@ -735,6 +966,94 @@ static int do_unshare(struct pkvm_mem_share *share)
 	return WARN_ON(__do_unshare(share));
 }
 
+static int check_donation(struct pkvm_mem_donation *donation)
+{
+	const struct pkvm_mem_transition *tx = &donation->tx;
+	u64 completer_addr;
+	int ret;
+
+	switch (tx->initiator.id) {
+	case PKVM_ID_HOST:
+		ret = host_request_owned_transition(&completer_addr, tx);
+		break;
+	case PKVM_ID_HYP:
+		ret = hyp_request_donation(&completer_addr, tx);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	if (ret)
+		return ret;
+
+	switch (tx->completer.id) {
+	case PKVM_ID_HOST:
+		ret = host_ack_donation(completer_addr, tx);
+		break;
+	case PKVM_ID_HYP:
+		ret = hyp_ack_donation(completer_addr, tx);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+static int __do_donate(struct pkvm_mem_donation *donation)
+{
+	const struct pkvm_mem_transition *tx = &donation->tx;
+	u64 completer_addr;
+	int ret;
+
+	switch (tx->initiator.id) {
+	case PKVM_ID_HOST:
+		ret = host_initiate_donation(&completer_addr, tx);
+		break;
+	case PKVM_ID_HYP:
+		ret = hyp_initiate_donation(&completer_addr, tx);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	if (ret)
+		return ret;
+
+	switch (tx->completer.id) {
+	case PKVM_ID_HOST:
+		ret = host_complete_donation(completer_addr, tx);
+		break;
+	case PKVM_ID_HYP:
+		ret = hyp_complete_donation(completer_addr, tx);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+/*
+ * do_donate():
+ *
+ * The page owner transfers ownership to another component, losing access
+ * as a consequence.
+ *
+ * Initiator: OWNED	=> NOPAGE
+ * Completer: NOPAGE	=> OWNED
+ */
+static int do_donate(struct pkvm_mem_donation *donation)
+{
+	int ret;
+
+	ret = check_donation(donation);
+	if (ret)
+		return ret;
+
+	return WARN_ON(__do_donate(donation));
+}
+
 int __pkvm_host_share_hyp(u64 pfn)
 {
 	int ret;
@@ -800,3 +1119,112 @@ int __pkvm_host_unshare_hyp(u64 pfn)
 
 	return ret;
 }
+
+int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages)
+{
+	int ret;
+	u64 host_addr = hyp_pfn_to_phys(pfn);
+	u64 hyp_addr = (u64)__hyp_va(host_addr);
+	struct pkvm_mem_donation donation = {
+		.tx	= {
+			.nr_pages	= nr_pages,
+			.initiator	= {
+				.id	= PKVM_ID_HOST,
+				.addr	= host_addr,
+				.host	= {
+					.completer_addr = hyp_addr,
+				},
+			},
+			.completer	= {
+				.id	= PKVM_ID_HYP,
+			},
+		},
+	};
+
+	host_lock_component();
+	hyp_lock_component();
+
+	ret = do_donate(&donation);
+
+	hyp_unlock_component();
+	host_unlock_component();
+
+	return ret;
+}
+
+int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages)
+{
+	int ret;
+	u64 host_addr = hyp_pfn_to_phys(pfn);
+	u64 hyp_addr = (u64)__hyp_va(host_addr);
+	struct pkvm_mem_donation donation = {
+		.tx	= {
+			.nr_pages	= nr_pages,
+			.initiator	= {
+				.id	= PKVM_ID_HYP,
+				.addr	= hyp_addr,
+				.hyp	= {
+					.completer_addr = host_addr,
+				},
+			},
+			.completer	= {
+				.id	= PKVM_ID_HOST,
+			},
+		},
+	};
+
+	host_lock_component();
+	hyp_lock_component();
+
+	ret = do_donate(&donation);
+
+	hyp_unlock_component();
+	host_unlock_component();
+
+	return ret;
+}
+
+int hyp_pin_shared_mem(void *from, void *to)
+{
+	u64 cur, start = ALIGN_DOWN((u64)from, PAGE_SIZE);
+	u64 end = PAGE_ALIGN((u64)to);
+	u64 size = end - start;
+	int ret;
+
+	host_lock_component();
+	hyp_lock_component();
+
+	ret = __host_check_page_state_range(__hyp_pa(start), size,
+					    PKVM_PAGE_SHARED_OWNED);
+	if (ret)
+		goto unlock;
+
+	ret = __hyp_check_page_state_range(start, size,
+					   PKVM_PAGE_SHARED_BORROWED);
+	if (ret)
+		goto unlock;
+
+	for (cur = start; cur < end; cur += PAGE_SIZE)
+		hyp_page_ref_inc(hyp_virt_to_page(cur));
+
+unlock:
+	hyp_unlock_component();
+	host_unlock_component();
+
+	return ret;
+}
+
+void hyp_unpin_shared_mem(void *from, void *to)
+{
+	u64 cur, start = ALIGN_DOWN((u64)from, PAGE_SIZE);
+	u64 end = PAGE_ALIGN((u64)to);
+
+	host_lock_component();
+	hyp_lock_component();
+
+	for (cur = start; cur < end; cur += PAGE_SIZE)
+		hyp_page_ref_dec(hyp_virt_to_page(cur));
+
+	hyp_unlock_component();
+	host_unlock_component();
+}