arch/arm64/kvm/hyp/nvhe/mem_protect.c - virt/kvm/kvm - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright (C) 2020 Google LLC
  * Author: Quentin Perret <qperret@google.com>
  */

 #include <linux/kvm_host.h>
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_hyp.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_pgtable.h>
 #include <asm/stage2_pgtable.h>

 #include <hyp/switch.h>

 #include <nvhe/gfp.h>
 #include <nvhe/memory.h>
 #include <nvhe/mem_protect.h>
 #include <nvhe/mm.h>

 #define KVM_HOST_S2_FLAGS (KVM_PGTABLE_S2_NOFWB | KVM_PGTABLE_S2_IDMAP)

 extern unsigned long hyp_nr_cpus;
 struct host_kvm host_kvm;

 static struct hyp_pool host_s2_pool;

 /*
  * Copies of the host's CPU features registers holding sanitized values.
  */
 u64 id_aa64mmfr0_el1_sys_val;
 u64 id_aa64mmfr1_el1_sys_val;

 const u8 pkvm_hyp_id = 1;

 static void *host_s2_zalloc_pages_exact(size_t size)
 {
 	void *addr = hyp_alloc_pages(&host_s2_pool, get_order(size));

 	hyp_split_page(hyp_virt_to_page(addr));

 	/*
 	 * The size of concatenated PGDs is always a power of two of PAGE_SIZE,
 	 * so there should be no need to free any of the tail pages to make the
 	 * allocation exact.
 	 */
 	WARN_ON(size != (PAGE_SIZE << get_order(size)));

 	return addr;
 }

 static void *host_s2_zalloc_page(void *pool)
 {
 	return hyp_alloc_pages(pool, 0);
 }

 static void host_s2_get_page(void *addr)
 {
 	hyp_get_page(&host_s2_pool, addr);
 }

 static void host_s2_put_page(void *addr)
 {
 	hyp_put_page(&host_s2_pool, addr);
 }

 static int prepare_s2_pool(void *pgt_pool_base)
 {
 	unsigned long nr_pages, pfn;
 	int ret;

 	pfn = hyp_virt_to_pfn(pgt_pool_base);
 	nr_pages = host_s2_pgtable_pages();
 	ret = hyp_pool_init(&host_s2_pool, pfn, nr_pages, 0);
 	if (ret)
 		return ret;

 	host_kvm.mm_ops = (struct kvm_pgtable_mm_ops) {
 		.zalloc_pages_exact = host_s2_zalloc_pages_exact,
 		.zalloc_page = host_s2_zalloc_page,
 		.phys_to_virt = hyp_phys_to_virt,
 		.virt_to_phys = hyp_virt_to_phys,
 		.page_count = hyp_page_count,
 		.get_page = host_s2_get_page,
 		.put_page = host_s2_put_page,
 	};

 	return 0;
 }

 static void prepare_host_vtcr(void)
 {
 	u32 parange, phys_shift;

 	/* The host stage 2 is id-mapped, so use parange for T0SZ */
 	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,
 					  id_aa64mmfr1_el1_sys_val, phys_shift);
 }

 static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot);

 int kvm_host_prepare_stage2(void *pgt_pool_base)
 {
 	struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
 	int ret;

 	prepare_host_vtcr();
 	hyp_spin_lock_init(&host_kvm.lock);

 	ret = prepare_s2_pool(pgt_pool_base);
 	if (ret)
 		return ret;

 	ret = __kvm_pgtable_stage2_init(&host_kvm.pgt, &host_kvm.arch,
 					&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);

 	return 0;
 }

 int __pkvm_prot_finalize(void)
 {
 	struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
 	struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);

 	params->vttbr = kvm_get_vttbr(mmu);
 	params->vtcr = host_kvm.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);

 	/*
 	 * Make sure to have an ISB before the TLB maintenance below but only
 	 * when __load_stage2() doesn't include one already.
 	 */
 	asm(ALTERNATIVE("isb", "nop", ARM64_WORKAROUND_SPECULATIVE_AT));

 	/* Invalidate stale HCR bits that may be cached in TLBs */
 	__tlbi(vmalls12e1);
 	dsb(nsh);
 	isb();

 	return 0;
 }

 static int host_stage2_unmap_dev_all(void)
 {
 	struct kvm_pgtable *pgt = &host_kvm.pgt;
 	struct memblock_region *reg;
 	u64 addr = 0;
 	int i, ret;

 	/* Unmap all non-memory regions to recycle the pages */
 	for (i = 0; i < hyp_memblock_nr; i++, addr = reg->base + reg->size) {
 		reg = &hyp_memory[i];
 		ret = kvm_pgtable_stage2_unmap(pgt, addr, reg->base - addr);
 		if (ret)
 			return ret;
 	}
 	return kvm_pgtable_stage2_unmap(pgt, addr, BIT(pgt->ia_bits) - addr);
 }

 struct kvm_mem_range {
 	u64 start;
 	u64 end;
 };

 static bool find_mem_range(phys_addr_t addr, struct kvm_mem_range *range)
 {
 	int cur, left = 0, right = hyp_memblock_nr;
 	struct memblock_region *reg;
 	phys_addr_t end;

 	range->start = 0;
 	range->end = ULONG_MAX;

 	/* The list of memblock regions is sorted, binary search it */
 	while (left < right) {
 		cur = (left + right) >> 1;
 		reg = &hyp_memory[cur];
 		end = reg->base + reg->size;
 		if (addr < reg->base) {
 			right = cur;
 			range->end = reg->base;
 		} else if (addr >= end) {
 			left = cur + 1;
 			range->start = end;
 		} else {
 			range->start = reg->base;
 			range->end = end;
 			return true;
 		}
 	}

 	return false;
 }

 bool addr_is_memory(phys_addr_t phys)
 {
 	struct kvm_mem_range range;

 	return find_mem_range(phys, &range);
 }

 static bool is_in_mem_range(u64 addr, struct kvm_mem_range *range)
 {
 	return range->start <= addr && addr < range->end;
 }

 static bool range_is_memory(u64 start, u64 end)
 {
 	struct kvm_mem_range r;

 	if (!find_mem_range(start, &r))
 		return false;

 	return is_in_mem_range(end - 1, &r);
 }

 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,
 				      prot, &host_s2_pool);
 }

 /*
  * The pool has been provided with enough pages to cover all of memory with
  * page granularity, but it is difficult to know how much of the MMIO range
  * we will need to cover upfront, so we may need to 'recycle' the pages if we
  * run out.
  */
 #define host_stage2_try(fn, ...)					\
 	({								\
 		int __ret;						\
 		hyp_assert_lock_held(&host_kvm.lock);			\
 		__ret = fn(__VA_ARGS__);				\
 		if (__ret == -ENOMEM) {					\
 			__ret = host_stage2_unmap_dev_all();		\
 			if (!__ret)					\
 				__ret = fn(__VA_ARGS__);		\
 		}							\
 		__ret;							\
 	 })

 static inline bool range_included(struct kvm_mem_range *child,
 				  struct kvm_mem_range *parent)
 {
 	return parent->start <= child->start && child->end <= parent->end;
 }

 static int host_stage2_adjust_range(u64 addr, struct kvm_mem_range *range)
 {
 	struct kvm_mem_range cur;
 	kvm_pte_t pte;
 	u32 level;
 	int ret;

 	hyp_assert_lock_held(&host_kvm.lock);
 	ret = kvm_pgtable_get_leaf(&host_kvm.pgt, addr, &pte, &level);
 	if (ret)
 		return ret;

 	if (kvm_pte_valid(pte))
 		return -EAGAIN;

 	if (pte)
 		return -EPERM;

 	do {
 		u64 granule = kvm_granule_size(level);
 		cur.start = ALIGN_DOWN(addr, granule);
 		cur.end = cur.start + granule;
 		level++;
 	} while ((level < KVM_PGTABLE_MAX_LEVELS) &&
 			!(kvm_level_supports_block_mapping(level) &&
 			  range_included(&cur, range)));

 	*range = cur;

 	return 0;
 }

 int host_stage2_idmap_locked(phys_addr_t addr, u64 size,
 			     enum kvm_pgtable_prot prot)
 {
 	hyp_assert_lock_held(&host_kvm.lock);

 	return host_stage2_try(__host_stage2_idmap, addr, addr + size, prot);
 }

 int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id)
 {
 	hyp_assert_lock_held(&host_kvm.lock);

 	return host_stage2_try(kvm_pgtable_stage2_set_owner, &host_kvm.pgt,
 			       addr, size, &host_s2_pool, owner_id);
 }

 static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot)
 {
 	/*
 	 * Block mappings must be used with care in the host stage-2 as a
 	 * kvm_pgtable_stage2_map() operation targeting a page in the range of
 	 * an existing block will delete the block under the assumption that
 	 * mappings in the rest of the block range can always be rebuilt lazily.
 	 * That assumption is correct for the host stage-2 with RWX mappings
 	 * targeting memory or RW mappings targeting MMIO ranges (see
 	 * host_stage2_idmap() below which implements some of the host memory
 	 * abort logic). However, this is not safe for any other mappings where
 	 * the host stage-2 page-table is in fact the only place where this
 	 * state is stored. In all those cases, it is safer to use page-level
 	 * mappings, hence avoiding to lose the state because of side-effects in
 	 * kvm_pgtable_stage2_map().
 	 */
 	if (range_is_memory(addr, end))
 		return prot != PKVM_HOST_MEM_PROT;
 	else
 		return prot != PKVM_HOST_MMIO_PROT;
 }

 static int host_stage2_idmap(u64 addr)
 {
 	struct kvm_mem_range range;
 	bool is_memory = find_mem_range(addr, &range);
 	enum kvm_pgtable_prot prot;
 	int ret;

 	prot = is_memory ? PKVM_HOST_MEM_PROT : PKVM_HOST_MMIO_PROT;

 	hyp_spin_lock(&host_kvm.lock);
 	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);

 	return ret;
 }

 static inline bool check_prot(enum kvm_pgtable_prot prot,
 			      enum kvm_pgtable_prot required,
 			      enum kvm_pgtable_prot denied)
 {
 	return (prot & (required | denied)) == required;
 }

 int __pkvm_host_share_hyp(u64 pfn)
 {
 	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;

 	if (!addr_is_memory(addr))
 		return -EINVAL;

 	hyp_spin_lock(&host_kvm.lock);
 	hyp_spin_lock(&pkvm_pgd_lock);

 	ret = kvm_pgtable_get_leaf(&host_kvm.pgt, addr, &pte, NULL);
 	if (ret)
 		goto unlock;
 	if (!pte)
 		goto map_shared;

 	/*
 	 * 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;
 	}

 	state = pkvm_getstate(cur);
 	if (state == PKVM_PAGE_OWNED)
 		goto map_shared;

 	/*
 	 * 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;
 	}

 	ret = kvm_pgtable_get_leaf(&pkvm_pgtable, (u64)virt, &pte, NULL);
 	if (ret)
 		goto unlock;

 	/*
 	 * 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;

 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);

 	prot = pkvm_mkstate(PKVM_HOST_MEM_PROT, PKVM_PAGE_SHARED_OWNED);
 	ret = host_stage2_idmap_locked(addr, PAGE_SIZE, prot);
 	BUG_ON(ret);

 unlock:
 	hyp_spin_unlock(&pkvm_pgd_lock);
 	hyp_spin_unlock(&host_kvm.lock);

 	return ret;
 }

 void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
 {
 	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);
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright (C) 2020 Google LLC
	* Author: Quentin Perret <qperret@google.com>
	*/

	#include <linux/kvm_host.h>
	#include <asm/kvm_emulate.h>
	#include <asm/kvm_hyp.h>
	#include <asm/kvm_mmu.h>
	#include <asm/kvm_pgtable.h>
	#include <asm/stage2_pgtable.h>

	#include <hyp/switch.h>

	#include <nvhe/gfp.h>
	#include <nvhe/memory.h>
	#include <nvhe/mem_protect.h>
	#include <nvhe/mm.h>

	#define KVM_HOST_S2_FLAGS (KVM_PGTABLE_S2_NOFWB \| KVM_PGTABLE_S2_IDMAP)

	extern unsigned long hyp_nr_cpus;
	struct host_kvm host_kvm;

	static struct hyp_pool host_s2_pool;

	/*
	* Copies of the host's CPU features registers holding sanitized values.
	*/
	u64 id_aa64mmfr0_el1_sys_val;
	u64 id_aa64mmfr1_el1_sys_val;

	const u8 pkvm_hyp_id = 1;

	static void *host_s2_zalloc_pages_exact(size_t size)
	{
	void *addr = hyp_alloc_pages(&host_s2_pool, get_order(size));

	hyp_split_page(hyp_virt_to_page(addr));

	/*
	* The size of concatenated PGDs is always a power of two of PAGE_SIZE,
	* so there should be no need to free any of the tail pages to make the
	* allocation exact.
	*/
	WARN_ON(size != (PAGE_SIZE << get_order(size)));

	return addr;
	}

	static void host_s2_zalloc_page(void pool)
	{
	return hyp_alloc_pages(pool, 0);
	}

	static void host_s2_get_page(void *addr)
	{
	hyp_get_page(&host_s2_pool, addr);
	}

	static void host_s2_put_page(void *addr)
	{
	hyp_put_page(&host_s2_pool, addr);
	}

	static int prepare_s2_pool(void *pgt_pool_base)
	{
	unsigned long nr_pages, pfn;
	int ret;

	pfn = hyp_virt_to_pfn(pgt_pool_base);
	nr_pages = host_s2_pgtable_pages();
	ret = hyp_pool_init(&host_s2_pool, pfn, nr_pages, 0);
	if (ret)
	return ret;

	host_kvm.mm_ops = (struct kvm_pgtable_mm_ops) {
	.zalloc_pages_exact = host_s2_zalloc_pages_exact,
	.zalloc_page = host_s2_zalloc_page,
	.phys_to_virt = hyp_phys_to_virt,
	.virt_to_phys = hyp_virt_to_phys,
	.page_count = hyp_page_count,
	.get_page = host_s2_get_page,
	.put_page = host_s2_put_page,
	};

	return 0;
	}

	static void prepare_host_vtcr(void)
	{
	u32 parange, phys_shift;

	/* The host stage 2 is id-mapped, so use parange for T0SZ */
	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,
	id_aa64mmfr1_el1_sys_val, phys_shift);
	}

	static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot);

	int kvm_host_prepare_stage2(void *pgt_pool_base)
	{
	struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
	int ret;

	prepare_host_vtcr();
	hyp_spin_lock_init(&host_kvm.lock);

	ret = prepare_s2_pool(pgt_pool_base);
	if (ret)
	return ret;

	ret = __kvm_pgtable_stage2_init(&host_kvm.pgt, &host_kvm.arch,
	&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);

	return 0;
	}

	int __pkvm_prot_finalize(void)
	{
	struct kvm_s2_mmu *mmu = &host_kvm.arch.mmu;
	struct kvm_nvhe_init_params *params = this_cpu_ptr(&kvm_init_params);

	params->vttbr = kvm_get_vttbr(mmu);
	params->vtcr = host_kvm.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);

	/*
	* Make sure to have an ISB before the TLB maintenance below but only
	* when __load_stage2() doesn't include one already.
	*/
	asm(ALTERNATIVE("isb", "nop", ARM64_WORKAROUND_SPECULATIVE_AT));

	/* Invalidate stale HCR bits that may be cached in TLBs */
	__tlbi(vmalls12e1);
	dsb(nsh);
	isb();

	return 0;
	}

	static int host_stage2_unmap_dev_all(void)
	{
	struct kvm_pgtable *pgt = &host_kvm.pgt;
	struct memblock_region *reg;
	u64 addr = 0;
	int i, ret;

	/* Unmap all non-memory regions to recycle the pages */
	for (i = 0; i < hyp_memblock_nr; i++, addr = reg->base + reg->size) {
	reg = &hyp_memory[i];
	ret = kvm_pgtable_stage2_unmap(pgt, addr, reg->base - addr);
	if (ret)
	return ret;
	}
	return kvm_pgtable_stage2_unmap(pgt, addr, BIT(pgt->ia_bits) - addr);
	}

	struct kvm_mem_range {
	u64 start;
	u64 end;
	};

	static bool find_mem_range(phys_addr_t addr, struct kvm_mem_range *range)
	{
	int cur, left = 0, right = hyp_memblock_nr;
	struct memblock_region *reg;
	phys_addr_t end;

	range->start = 0;
	range->end = ULONG_MAX;

	/* The list of memblock regions is sorted, binary search it */
	while (left < right) {
	cur = (left + right) >> 1;
	reg = &hyp_memory[cur];
	end = reg->base + reg->size;
	if (addr < reg->base) {
	right = cur;
	range->end = reg->base;
	} else if (addr >= end) {
	left = cur + 1;
	range->start = end;
	} else {
	range->start = reg->base;
	range->end = end;
	return true;
	}
	}

	return false;
	}

	bool addr_is_memory(phys_addr_t phys)
	{
	struct kvm_mem_range range;

	return find_mem_range(phys, &range);
	}

	static bool is_in_mem_range(u64 addr, struct kvm_mem_range *range)
	{
	return range->start <= addr && addr < range->end;
	}

	static bool range_is_memory(u64 start, u64 end)
	{
	struct kvm_mem_range r;

	if (!find_mem_range(start, &r))
	return false;

	return is_in_mem_range(end - 1, &r);
	}

	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,
	prot, &host_s2_pool);
	}

	/*
	* The pool has been provided with enough pages to cover all of memory with
	* page granularity, but it is difficult to know how much of the MMIO range
	* we will need to cover upfront, so we may need to 'recycle' the pages if we
	* run out.
	*/
	#define host_stage2_try(fn, ...) \
	({ \
	int __ret; \
	hyp_assert_lock_held(&host_kvm.lock); \
	__ret = fn(__VA_ARGS__); \
	if (__ret == -ENOMEM) { \
	__ret = host_stage2_unmap_dev_all(); \
	if (!__ret) \
	__ret = fn(__VA_ARGS__); \
	} \
	__ret; \
	})

	static inline bool range_included(struct kvm_mem_range *child,
	struct kvm_mem_range *parent)
	{
	return parent->start <= child->start && child->end <= parent->end;
	}

	static int host_stage2_adjust_range(u64 addr, struct kvm_mem_range *range)
	{
	struct kvm_mem_range cur;
	kvm_pte_t pte;
	u32 level;
	int ret;

	hyp_assert_lock_held(&host_kvm.lock);
	ret = kvm_pgtable_get_leaf(&host_kvm.pgt, addr, &pte, &level);
	if (ret)
	return ret;

	if (kvm_pte_valid(pte))
	return -EAGAIN;

	if (pte)
	return -EPERM;

	do {
	u64 granule = kvm_granule_size(level);
	cur.start = ALIGN_DOWN(addr, granule);
	cur.end = cur.start + granule;
	level++;
	} while ((level < KVM_PGTABLE_MAX_LEVELS) &&
	!(kvm_level_supports_block_mapping(level) &&
	range_included(&cur, range)));

	*range = cur;

	return 0;
	}

	int host_stage2_idmap_locked(phys_addr_t addr, u64 size,
	enum kvm_pgtable_prot prot)
	{
	hyp_assert_lock_held(&host_kvm.lock);

	return host_stage2_try(__host_stage2_idmap, addr, addr + size, prot);
	}

	int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id)
	{
	hyp_assert_lock_held(&host_kvm.lock);

	return host_stage2_try(kvm_pgtable_stage2_set_owner, &host_kvm.pgt,
	addr, size, &host_s2_pool, owner_id);
	}

	static bool host_stage2_force_pte_cb(u64 addr, u64 end, enum kvm_pgtable_prot prot)
	{
	/*
	* Block mappings must be used with care in the host stage-2 as a
	* kvm_pgtable_stage2_map() operation targeting a page in the range of
	* an existing block will delete the block under the assumption that
	* mappings in the rest of the block range can always be rebuilt lazily.
	* That assumption is correct for the host stage-2 with RWX mappings
	* targeting memory or RW mappings targeting MMIO ranges (see
	* host_stage2_idmap() below which implements some of the host memory
	* abort logic). However, this is not safe for any other mappings where
	* the host stage-2 page-table is in fact the only place where this
	* state is stored. In all those cases, it is safer to use page-level
	* mappings, hence avoiding to lose the state because of side-effects in
	* kvm_pgtable_stage2_map().
	*/
	if (range_is_memory(addr, end))
	return prot != PKVM_HOST_MEM_PROT;
	else
	return prot != PKVM_HOST_MMIO_PROT;
	}

	static int host_stage2_idmap(u64 addr)
	{
	struct kvm_mem_range range;
	bool is_memory = find_mem_range(addr, &range);
	enum kvm_pgtable_prot prot;
	int ret;

	prot = is_memory ? PKVM_HOST_MEM_PROT : PKVM_HOST_MMIO_PROT;

	hyp_spin_lock(&host_kvm.lock);
	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);

	return ret;
	}

	static inline bool check_prot(enum kvm_pgtable_prot prot,
	enum kvm_pgtable_prot required,
	enum kvm_pgtable_prot denied)
	{
	return (prot & (required \| denied)) == required;
	}

	int __pkvm_host_share_hyp(u64 pfn)
	{
	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;

	if (!addr_is_memory(addr))
	return -EINVAL;

	hyp_spin_lock(&host_kvm.lock);
	hyp_spin_lock(&pkvm_pgd_lock);

	ret = kvm_pgtable_get_leaf(&host_kvm.pgt, addr, &pte, NULL);
	if (ret)
	goto unlock;
	if (!pte)
	goto map_shared;

	/*
	* 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;
	}

	state = pkvm_getstate(cur);
	if (state == PKVM_PAGE_OWNED)
	goto map_shared;

	/*
	* 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;
	}

	ret = kvm_pgtable_get_leaf(&pkvm_pgtable, (u64)virt, &pte, NULL);
	if (ret)
	goto unlock;

	/*
	* 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;

	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);

	prot = pkvm_mkstate(PKVM_HOST_MEM_PROT, PKVM_PAGE_SHARED_OWNED);
	ret = host_stage2_idmap_locked(addr, PAGE_SIZE, prot);
	BUG_ON(ret);

	unlock:
	hyp_spin_unlock(&pkvm_pgd_lock);
	hyp_spin_unlock(&host_kvm.lock);

	return ret;
	}

	void handle_host_mem_abort(struct kvm_cpu_context *host_ctxt)
	{
	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);
	}