8 files changed, 466 insertions, 93 deletions

diff --git a/arch/arm64/kvm/hyp/nvhe/Makefile b/arch/arm64/kvm/hyp/nvhe/Makefile
index c3c11974fa3b..24b2c2425b38 100644
--- a/arch/arm64/kvm/hyp/nvhe/Makefile
+++ b/arch/arm64/kvm/hyp/nvhe/Makefile
@@ -89,6 +89,7 @@ KBUILD_CFLAGS := $(filter-out $(CC_FLAGS_FTRACE) $(CC_FLAGS_SCS) $(CC_FLAGS_CFI)
 # cause crashes. Just disable it.
 GCOV_PROFILE	:= n
 KASAN_SANITIZE	:= n
+KCSAN_SANITIZE	:= n
 UBSAN_SANITIZE	:= n
 KCOV_INSTRUMENT	:= n
 
diff --git a/arch/arm64/kvm/hyp/nvhe/early_alloc.c b/arch/arm64/kvm/hyp/nvhe/early_alloc.c
index 1306c430ab87..00de04153cc6 100644
--- a/arch/arm64/kvm/hyp/nvhe/early_alloc.c
+++ b/arch/arm64/kvm/hyp/nvhe/early_alloc.c
@@ -43,6 +43,9 @@ void *hyp_early_alloc_page(void *arg)
 	return hyp_early_alloc_contig(1);
 }
 
+static void hyp_early_alloc_get_page(void *addr) { }
+static void hyp_early_alloc_put_page(void *addr) { }
+
 void hyp_early_alloc_init(void *virt, unsigned long size)
 {
 	base = cur = (unsigned long)virt;
@@ -51,4 +54,6 @@ void hyp_early_alloc_init(void *virt, unsigned long size)
 	hyp_early_alloc_mm_ops.zalloc_page = hyp_early_alloc_page;
 	hyp_early_alloc_mm_ops.phys_to_virt = hyp_phys_to_virt;
 	hyp_early_alloc_mm_ops.virt_to_phys = hyp_virt_to_phys;
+	hyp_early_alloc_mm_ops.get_page = hyp_early_alloc_get_page;
+	hyp_early_alloc_mm_ops.put_page = hyp_early_alloc_put_page;
 }
diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
index b096bf009144..5e2197db0d32 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -147,6 +147,13 @@ static void handle___pkvm_host_share_hyp(struct kvm_cpu_context *host_ctxt)
 	cpu_reg(host_ctxt, 1) = __pkvm_host_share_hyp(pfn);
 }
 
+static void handle___pkvm_host_unshare_hyp(struct kvm_cpu_context *host_ctxt)
+{
+	DECLARE_REG(u64, pfn, host_ctxt, 1);
+
+	cpu_reg(host_ctxt, 1) = __pkvm_host_unshare_hyp(pfn);
+}
+
 static void handle___pkvm_create_private_mapping(struct kvm_cpu_context *host_ctxt)
 {
 	DECLARE_REG(phys_addr_t, phys, host_ctxt, 1);
@@ -184,6 +191,7 @@ static const hcall_t host_hcall[] = {
 	HANDLE_FUNC(__pkvm_prot_finalize),
 
 	HANDLE_FUNC(__pkvm_host_share_hyp),
+	HANDLE_FUNC(__pkvm_host_unshare_hyp),
 	HANDLE_FUNC(__kvm_adjust_pc),
 	HANDLE_FUNC(__kvm_vcpu_run),
 	HANDLE_FUNC(__kvm_flush_vm_context),
diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index c1a90dd022b8..674f10564373 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
@@ -9,6 +9,7 @@
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_pgtable.h>
+#include <asm/kvm_pkvm.h>
 #include <asm/stage2_pgtable.h>
 
 #include <hyp/fault.h>
@@ -27,6 +28,26 @@ static struct hyp_pool host_s2_pool;
 
 const u8 pkvm_hyp_id = 1;
 
+static void host_lock_component(void)
+{
+	hyp_spin_lock(&host_kvm.lock);
+}
+
+static void host_unlock_component(void)
+{
+	hyp_spin_unlock(&host_kvm.lock);
+}
+
+static void hyp_lock_component(void)
+{
+	hyp_spin_lock(&pkvm_pgd_lock);
+}
+
+static void hyp_unlock_component(void)
+{
+	hyp_spin_unlock(&pkvm_pgd_lock);
+}
+
 static void *host_s2_zalloc_pages_exact(size_t size)
 {
 	void *addr = hyp_alloc_pages(&host_s2_pool, get_order(size));
@@ -103,19 +124,19 @@ int kvm_host_prepare_stage2(void *pgt_pool_base)
 
 	prepare_host_vtcr();
 	hyp_spin_lock_init(&host_kvm.lock);
+	mmu->arch = &host_kvm.arch;
 
 	ret = prepare_s2_pool(pgt_pool_base);
 	if (ret)
 		return ret;
 
-	ret = __kvm_pgtable_stage2_init(&host_kvm.pgt, &host_kvm.arch,
+	ret = __kvm_pgtable_stage2_init(&host_kvm.pgt, mmu,
 					&host_kvm.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->arch = &host_kvm.arch;
 	mmu->pgt = &host_kvm.pgt;
 	WRITE_ONCE(mmu->vmid.vmid_gen, 0);
 	WRITE_ONCE(mmu->vmid.vmid, 0);
@@ -338,116 +359,446 @@ static int host_stage2_idmap(u64 addr)
 
 	prot = is_memory ? PKVM_HOST_MEM_PROT : PKVM_HOST_MMIO_PROT;
 
-	hyp_spin_lock(&host_kvm.lock);
+	host_lock_component();
 	ret = host_stage2_adjust_range(addr, &range);
 	if (ret)
 		goto unlock;
 
 	ret = host_stage2_idmap_locked(range.start, range.end - range.start, prot);
 unlock:
-	hyp_spin_unlock(&host_kvm.lock);
+	host_unlock_component();
 
 	return ret;
 }
 
-static inline bool check_prot(enum kvm_pgtable_prot prot,
-			      enum kvm_pgtable_prot required,
-			      enum kvm_pgtable_prot denied)
+void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
 {
-	return (prot & (required | denied)) == required;
+	struct kvm_vcpu_fault_info fault;
+	u64 esr, addr;
+	int ret = 0;
+
+	esr = read_sysreg_el2(SYS_ESR);
+	BUG_ON(!__get_fault_info(esr, &fault));
+
+	addr = (fault.hpfar_el2 & HPFAR_MASK) << 8;
+	ret = host_stage2_idmap(addr);
+	BUG_ON(ret && ret != -EAGAIN);
 }
 
-int __pkvm_host_share_hyp(u64 pfn)
+/* This corresponds to locking order */
+enum pkvm_component_id {
+	PKVM_ID_HOST,
+	PKVM_ID_HYP,
+};
+
+struct pkvm_mem_transition {
+	u64				nr_pages;
+
+	struct {
+		enum pkvm_component_id	id;
+		/* Address in the initiator's address space */
+		u64			addr;
+
+		union {
+			struct {
+				/* Address in the completer's address space */
+				u64	completer_addr;
+			} host;
+		};
+	} initiator;
+
+	struct {
+		enum pkvm_component_id	id;
+	} completer;
+};
+
+struct pkvm_mem_share {
+	const struct pkvm_mem_transition	tx;
+	const enum kvm_pgtable_prot		completer_prot;
+};
+
+struct check_walk_data {
+	enum pkvm_page_state	desired;
+	enum pkvm_page_state	(*get_page_state)(kvm_pte_t pte);
+};
+
+static int __check_page_state_visitor(u64 addr, u64 end, u32 level,
+				      kvm_pte_t *ptep,
+				      enum kvm_pgtable_walk_flags flag,
+				      void * const arg)
 {
-	phys_addr_t addr = hyp_pfn_to_phys(pfn);
-	enum kvm_pgtable_prot prot, cur;
-	void *virt = __hyp_va(addr);
-	enum pkvm_page_state state;
-	kvm_pte_t pte;
-	int ret;
+	struct check_walk_data *d = arg;
+	kvm_pte_t pte = *ptep;
 
-	if (!addr_is_memory(addr))
+	if (kvm_pte_valid(pte) && !addr_is_memory(kvm_pte_to_phys(pte)))
 		return -EINVAL;
 
-	hyp_spin_lock(&host_kvm.lock);
-	hyp_spin_lock(&pkvm_pgd_lock);
+	return d->get_page_state(pte) == d->desired ? 0 : -EPERM;
+}
+
+static int check_page_state_range(struct kvm_pgtable *pgt, u64 addr, u64 size,
+				  struct check_walk_data *data)
+{
+	struct kvm_pgtable_walker walker = {
+		.cb	= __check_page_state_visitor,
+		.arg	= data,
+		.flags	= KVM_PGTABLE_WALK_LEAF,
+	};
+
+	return kvm_pgtable_walk(pgt, addr, size, &walker);
+}
+
+static enum pkvm_page_state host_get_page_state(kvm_pte_t pte)
+{
+	if (!kvm_pte_valid(pte) && pte)
+		return PKVM_NOPAGE;
+
+	return pkvm_getstate(kvm_pgtable_stage2_pte_prot(pte));
+}
+
+static int __host_check_page_state_range(u64 addr, u64 size,
+					 enum pkvm_page_state state)
+{
+	struct check_walk_data d = {
+		.desired	= state,
+		.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);
+}
+
+static int __host_set_page_state_range(u64 addr, u64 size,
+				       enum pkvm_page_state state)
+{
+	enum kvm_pgtable_prot prot = pkvm_mkstate(PKVM_HOST_MEM_PROT, state);
+
+	return host_stage2_idmap_locked(addr, size, prot);
+}
+
+static int host_request_owned_transition(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.host.completer_addr;
+	return __host_check_page_state_range(addr, size, PKVM_PAGE_OWNED);
+}
+
+static int host_request_unshare(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.host.completer_addr;
+	return __host_check_page_state_range(addr, size, PKVM_PAGE_SHARED_OWNED);
+}
+
+static int host_initiate_share(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.host.completer_addr;
+	return __host_set_page_state_range(addr, size, PKVM_PAGE_SHARED_OWNED);
+}
+
+static int host_initiate_unshare(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.host.completer_addr;
+	return __host_set_page_state_range(addr, size, PKVM_PAGE_OWNED);
+}
+
+static enum pkvm_page_state hyp_get_page_state(kvm_pte_t pte)
+{
+	if (!kvm_pte_valid(pte))
+		return PKVM_NOPAGE;
+
+	return pkvm_getstate(kvm_pgtable_stage2_pte_prot(pte));
+}
+
+static int __hyp_check_page_state_range(u64 addr, u64 size,
+					enum pkvm_page_state state)
+{
+	struct check_walk_data d = {
+		.desired	= state,
+		.get_page_state	= hyp_get_page_state,
+	};
+
+	hyp_assert_lock_held(&pkvm_pgd_lock);
+	return check_page_state_range(&pkvm_pgtable, addr, size, &d);
+}
+
+static bool __hyp_ack_skip_pgtable_check(const struct pkvm_mem_transition *tx)
+{
+	return !(IS_ENABLED(CONFIG_NVHE_EL2_DEBUG) ||
+		 tx->initiator.id != PKVM_ID_HOST);
+}
+
+static int hyp_ack_share(u64 addr, const struct pkvm_mem_transition *tx,
+			 enum kvm_pgtable_prot perms)
+{
+	u64 size = tx->nr_pages * PAGE_SIZE;
+
+	if (perms != PAGE_HYP)
+		return -EPERM;
+
+	if (__hyp_ack_skip_pgtable_check(tx))
+		return 0;
+
+	return __hyp_check_page_state_range(addr, size, PKVM_NOPAGE);
+}
+
+static int hyp_ack_unshare(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_PAGE_SHARED_BORROWED);
+}
+
+static int hyp_complete_share(u64 addr, const struct pkvm_mem_transition *tx,
+			      enum kvm_pgtable_prot perms)
+{
+	void *start = (void *)addr, *end = start + (tx->nr_pages * PAGE_SIZE);
+	enum kvm_pgtable_prot prot;
+
+	prot = pkvm_mkstate(perms, PKVM_PAGE_SHARED_BORROWED);
+	return pkvm_create_mappings_locked(start, end, prot);
+}
+
+static int hyp_complete_unshare(u64 addr, const struct pkvm_mem_transition *tx)
+{
+	u64 size = tx->nr_pages * PAGE_SIZE;
+	int ret = kvm_pgtable_hyp_unmap(&pkvm_pgtable, addr, size);
+
+	return (ret != size) ? -EFAULT : 0;
+}
+
+static int check_share(struct pkvm_mem_share *share)
+{
+	const struct pkvm_mem_transition *tx = &share->tx;
+	u64 completer_addr;
+	int ret;
+
+	switch (tx->initiator.id) {
+	case PKVM_ID_HOST:
+		ret = host_request_owned_transition(&completer_addr, tx);
+		break;
+	default:
+		ret = -EINVAL;
+	}
 
-	ret = kvm_pgtable_get_leaf(&host_kvm.pgt, addr, &pte, NULL);
 	if (ret)
-		goto unlock;
-	if (!pte)
-		goto map_shared;
+		return ret;
 
-	/*
-	 * Check attributes in the host stage-2 PTE. We need the page to be:
-	 *  - mapped RWX as we're sharing memory;
-	 *  - not borrowed, as that implies absence of ownership.
-	 * Otherwise, we can't let it got through
-	 */
-	cur = kvm_pgtable_stage2_pte_prot(pte);
-	prot = pkvm_mkstate(0, PKVM_PAGE_SHARED_BORROWED);
-	if (!check_prot(cur, PKVM_HOST_MEM_PROT, prot)) {
-		ret = -EPERM;
-		goto unlock;
+	switch (tx->completer.id) {
+	case PKVM_ID_HYP:
+		ret = hyp_ack_share(completer_addr, tx, share->completer_prot);
+		break;
+	default:
+		ret = -EINVAL;
 	}
 
-	state = pkvm_getstate(cur);
-	if (state == PKVM_PAGE_OWNED)
-		goto map_shared;
+	return ret;
+}
 
-	/*
-	 * Tolerate double-sharing the same page, but this requires
-	 * cross-checking the hypervisor stage-1.
-	 */
-	if (state != PKVM_PAGE_SHARED_OWNED) {
-		ret = -EPERM;
-		goto unlock;
+static int __do_share(struct pkvm_mem_share *share)
+{
+	const struct pkvm_mem_transition *tx = &share->tx;
+	u64 completer_addr;
+	int ret;
+
+	switch (tx->initiator.id) {
+	case PKVM_ID_HOST:
+		ret = host_initiate_share(&completer_addr, tx);
+		break;
+	default:
+		ret = -EINVAL;
 	}
 
-	ret = kvm_pgtable_get_leaf(&pkvm_pgtable, (u64)virt, &pte, NULL);
 	if (ret)
-		goto unlock;
+		return ret;
 
-	/*
-	 * If the page has been shared with the hypervisor, it must be
-	 * already mapped as SHARED_BORROWED in its stage-1.
-	 */
-	cur = kvm_pgtable_hyp_pte_prot(pte);
-	prot = pkvm_mkstate(PAGE_HYP, PKVM_PAGE_SHARED_BORROWED);
-	if (!check_prot(cur, prot, ~prot))
-		ret = -EPERM;
-	goto unlock;
+	switch (tx->completer.id) {
+	case PKVM_ID_HYP:
+		ret = hyp_complete_share(completer_addr, tx, share->completer_prot);
+		break;
+	default:
+		ret = -EINVAL;
+	}
 
-map_shared:
-	/*
-	 * If the page is not yet shared, adjust mappings in both page-tables
-	 * while both locks are held.
-	 */
-	prot = pkvm_mkstate(PAGE_HYP, PKVM_PAGE_SHARED_BORROWED);
-	ret = pkvm_create_mappings_locked(virt, virt + PAGE_SIZE, prot);
-	BUG_ON(ret);
+	return ret;
+}
+
+/*
+ * do_share():
+ *
+ * The page owner grants access to another component with a given set
+ * of permissions.
+ *
+ * Initiator: OWNED	=> SHARED_OWNED
+ * Completer: NOPAGE	=> SHARED_BORROWED
+ */
+static int do_share(struct pkvm_mem_share *share)
+{
+	int ret;
 
-	prot = pkvm_mkstate(PKVM_HOST_MEM_PROT, PKVM_PAGE_SHARED_OWNED);
-	ret = host_stage2_idmap_locked(addr, PAGE_SIZE, prot);
-	BUG_ON(ret);
+	ret = check_share(share);
+	if (ret)
+		return ret;
 
-unlock:
-	hyp_spin_unlock(&pkvm_pgd_lock);
-	hyp_spin_unlock(&host_kvm.lock);
+	return WARN_ON(__do_share(share));
+}
+
+static int check_unshare(struct pkvm_mem_share *share)
+{
+	const struct pkvm_mem_transition *tx = &share->tx;
+	u64 completer_addr;
+	int ret;
+
+	switch (tx->initiator.id) {
+	case PKVM_ID_HOST:
+		ret = host_request_unshare(&completer_addr, tx);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	if (ret)
+		return ret;
+
+	switch (tx->completer.id) {
+	case PKVM_ID_HYP:
+		ret = hyp_ack_unshare(completer_addr, tx);
+		break;
+	default:
+		ret = -EINVAL;
+	}
 
 	return ret;
 }
 
-void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
+static int __do_unshare(struct pkvm_mem_share *share)
 {
-	struct kvm_vcpu_fault_info fault;
-	u64 esr, addr;
-	int ret = 0;
+	const struct pkvm_mem_transition *tx = &share->tx;
+	u64 completer_addr;
+	int ret;
 
-	esr = read_sysreg_el2(SYS_ESR);
-	BUG_ON(!__get_fault_info(esr, &fault));
+	switch (tx->initiator.id) {
+	case PKVM_ID_HOST:
+		ret = host_initiate_unshare(&completer_addr, tx);
+		break;
+	default:
+		ret = -EINVAL;
+	}
 
-	addr = (fault.hpfar_el2 & HPFAR_MASK) << 8;
-	ret = host_stage2_idmap(addr);
-	BUG_ON(ret && ret != -EAGAIN);
+	if (ret)
+		return ret;
+
+	switch (tx->completer.id) {
+	case PKVM_ID_HYP:
+		ret = hyp_complete_unshare(completer_addr, tx);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+
+/*
+ * do_unshare():
+ *
+ * The page owner revokes access from another component for a range of
+ * pages which were previously shared using do_share().
+ *
+ * Initiator: SHARED_OWNED	=> OWNED
+ * Completer: SHARED_BORROWED	=> NOPAGE
+ */
+static int do_unshare(struct pkvm_mem_share *share)
+{
+	int ret;
+
+	ret = check_unshare(share);
+	if (ret)
+		return ret;
+
+	return WARN_ON(__do_unshare(share));
+}
+
+int __pkvm_host_share_hyp(u64 pfn)
+{
+	int ret;
+	u64 host_addr = hyp_pfn_to_phys(pfn);
+	u64 hyp_addr = (u64)__hyp_va(host_addr);
+	struct pkvm_mem_share share = {
+		.tx	= {
+			.nr_pages	= 1,
+			.initiator	= {
+				.id	= PKVM_ID_HOST,
+				.addr	= host_addr,
+				.host	= {
+					.completer_addr = hyp_addr,
+				},
+			},
+			.completer	= {
+				.id	= PKVM_ID_HYP,
+			},
+		},
+		.completer_prot	= PAGE_HYP,
+	};
+
+	host_lock_component();
+	hyp_lock_component();
+
+	ret = do_share(&share);
+
+	hyp_unlock_component();
+	host_unlock_component();
+
+	return ret;
+}
+
+int __pkvm_host_unshare_hyp(u64 pfn)
+{
+	int ret;
+	u64 host_addr = hyp_pfn_to_phys(pfn);
+	u64 hyp_addr = (u64)__hyp_va(host_addr);
+	struct pkvm_mem_share share = {
+		.tx	= {
+			.nr_pages	= 1,
+			.initiator	= {
+				.id	= PKVM_ID_HOST,
+				.addr	= host_addr,
+				.host	= {
+					.completer_addr = hyp_addr,
+				},
+			},
+			.completer	= {
+				.id	= PKVM_ID_HYP,
+			},
+		},
+		.completer_prot	= PAGE_HYP,
+	};
+
+	host_lock_component();
+	hyp_lock_component();
+
+	ret = do_unshare(&share);
+
+	hyp_unlock_component();
+	host_unlock_component();
+
+	return ret;
 }
diff --git a/arch/arm64/kvm/hyp/nvhe/mm.c b/arch/arm64/kvm/hyp/nvhe/mm.c
index 2fabeceb889a..526a7d6fa86f 100644
--- a/arch/arm64/kvm/hyp/nvhe/mm.c
+++ b/arch/arm64/kvm/hyp/nvhe/mm.c
@@ -8,6 +8,7 @@
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_pgtable.h>
+#include <asm/kvm_pkvm.h>
 #include <asm/spectre.h>
 
 #include <nvhe/early_alloc.h>
@@ -18,11 +19,12 @@
 
 struct kvm_pgtable pkvm_pgtable;
 hyp_spinlock_t pkvm_pgd_lock;
-u64 __io_map_base;
 
 struct memblock_region hyp_memory[HYP_MEMBLOCK_REGIONS];
 unsigned int hyp_memblock_nr;
 
+static u64 __io_map_base;
+
 static int __pkvm_create_mappings(unsigned long start, unsigned long size,
 				  unsigned long phys, enum kvm_pgtable_prot prot)
 {
diff --git a/arch/arm64/kvm/hyp/nvhe/page_alloc.c b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
index 0bd7701ad1df..543cad6c376a 100644
--- a/arch/arm64/kvm/hyp/nvhe/page_alloc.c
+++ b/arch/arm64/kvm/hyp/nvhe/page_alloc.c
@@ -241,7 +241,7 @@ int hyp_pool_init(struct hyp_pool *pool, u64 pfn, unsigned int nr_pages,
 	int i;
 
 	hyp_spin_lock_init(&pool->lock);
-	pool->max_order = min(MAX_ORDER, get_order(nr_pages << PAGE_SHIFT));
+	pool->max_order = min(MAX_ORDER, get_order((nr_pages + 1) << PAGE_SHIFT));
 	for (i = 0; i < pool->max_order; i++)
 		INIT_LIST_HEAD(&pool->free_area[i]);
 	pool->range_start = phys;
diff --git a/arch/arm64/kvm/hyp/nvhe/setup.c b/arch/arm64/kvm/hyp/nvhe/setup.c
index 578f71798c2e..27af337f9fea 100644
--- a/arch/arm64/kvm/hyp/nvhe/setup.c
+++ b/arch/arm64/kvm/hyp/nvhe/setup.c
@@ -8,6 +8,7 @@
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_pgtable.h>
+#include <asm/kvm_pkvm.h>
 
 #include <nvhe/early_alloc.h>
 #include <nvhe/fixed_config.h>
@@ -17,7 +18,6 @@
 #include <nvhe/mm.h>
 #include <nvhe/trap_handler.h>
 
-struct hyp_pool hpool;
 unsigned long hyp_nr_cpus;
 
 #define hyp_percpu_size ((unsigned long)__per_cpu_end - \
@@ -27,6 +27,7 @@ static void *vmemmap_base;
 static void *hyp_pgt_base;
 static void *host_s2_pgt_base;
 static struct kvm_pgtable_mm_ops pkvm_pgtable_mm_ops;
+static struct hyp_pool hpool;
 
 static int divide_memory_pool(void *virt, unsigned long size)
 {
@@ -165,6 +166,7 @@ static int finalize_host_mappings_walker(u64 addr, u64 end, u32 level,
 					 enum kvm_pgtable_walk_flags flag,
 					 void * const arg)
 {
+	struct kvm_pgtable_mm_ops *mm_ops = arg;
 	enum kvm_pgtable_prot prot;
 	enum pkvm_page_state state;
 	kvm_pte_t pte = *ptep;
@@ -173,6 +175,15 @@ static int finalize_host_mappings_walker(u64 addr, u64 end, u32 level,
 	if (!kvm_pte_valid(pte))
 		return 0;
 
+	/*
+	 * Fix-up the refcount for the page-table pages as the early allocator
+	 * was unable to access the hyp_vmemmap and so the buddy allocator has
+	 * initialised the refcount to '1'.
+	 */
+	mm_ops->get_page(ptep);
+	if (flag != KVM_PGTABLE_WALK_LEAF)
+		return 0;
+
 	if (level != (KVM_PGTABLE_MAX_LEVELS - 1))
 		return -EINVAL;
 
@@ -205,7 +216,8 @@ static int finalize_host_mappings(void)
 {
 	struct kvm_pgtable_walker walker = {
 		.cb	= finalize_host_mappings_walker,
-		.flags	= KVM_PGTABLE_WALK_LEAF,
+		.flags	= KVM_PGTABLE_WALK_LEAF | KVM_PGTABLE_WALK_TABLE_POST,
+		.arg	= pkvm_pgtable.mm_ops,
 	};
 	int i, ret;
 
@@ -240,19 +252,20 @@ void __noreturn __pkvm_init_finalise(void)
 	if (ret)
 		goto out;
 
-	ret = finalize_host_mappings();
-	if (ret)
-		goto out;
-
 	pkvm_pgtable_mm_ops = (struct kvm_pgtable_mm_ops) {
 		.zalloc_page = hyp_zalloc_hyp_page,
 		.phys_to_virt = hyp_phys_to_virt,
 		.virt_to_phys = hyp_virt_to_phys,
 		.get_page = hpool_get_page,
 		.put_page = hpool_put_page,
+		.page_count = hyp_page_count,
 	};
 	pkvm_pgtable.mm_ops = &pkvm_pgtable_mm_ops;
 
+	ret = finalize_host_mappings();
+	if (ret)
+		goto out;
+
 out:
 	/*
 	 * We tail-called to here from handle___pkvm_init() and will not return,
diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
index c0e3fed26d93..6410d21d8695 100644
--- a/arch/arm64/kvm/hyp/nvhe/switch.c
+++ b/arch/arm64/kvm/hyp/nvhe/switch.c
@@ -25,7 +25,6 @@
 #include <asm/fpsimd.h>
 #include <asm/debug-monitors.h>
 #include <asm/processor.h>
-#include <asm/thread_info.h>
 
 #include <nvhe/fixed_config.h>
 #include <nvhe/mem_protect.h>
@@ -233,7 +232,7 @@ static const exit_handler_fn *kvm_get_exit_handler_array(struct kvm_vcpu *vcpu)
  * Returns false if the guest ran in AArch32 when it shouldn't have, and
  * thus should exit to the host, or true if a the guest run loop can continue.
  */
-static bool handle_aarch32_guest(struct kvm_vcpu *vcpu, u64 *exit_code)
+static void early_exit_filter(struct kvm_vcpu *vcpu, u64 *exit_code)
 {
 	struct kvm *kvm = kern_hyp_va(vcpu->kvm);
 
@@ -248,10 +247,7 @@ static bool handle_aarch32_guest(struct kvm_vcpu *vcpu, u64 *exit_code)
 		vcpu->arch.target = -1;
 		*exit_code &= BIT(ARM_EXIT_WITH_SERROR_BIT);
 		*exit_code |= ARM_EXCEPTION_IL;
-		return false;
 	}
-
-	return true;
 }
 
 /* Switch to the guest for legacy non-VHE systems */
@@ -316,9 +312,6 @@ int __kvm_vcpu_run(struct kvm_vcpu *vcpu)
 		/* Jump in the fire! */
 		exit_code = __guest_enter(vcpu);
 
-		if (unlikely(!handle_aarch32_guest(vcpu, &exit_code)))
-			break;
-
 		/* And we're baaack! */
 	} while (fixup_guest_exit(vcpu, &exit_code));