// 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/kvm_pkvm.h>
#include <asm/stage2_pgtable.h>

#include <hyp/fault.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_AS_S1 | KVM_PGTABLE_S2_IDMAP)

struct host_mmu host_mmu;

static struct hyp_pool host_s2_pool;

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_mmu.lock);
}

static void host_unlock_component(void)
{
        hyp_spin_unlock(&host_mmu.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);
}

#define for_each_hyp_page(__p, __st, __sz)                              \
        for (struct hyp_page *__p = hyp_phys_to_page(__st),             \
                             *__e = __p + ((__sz) >> PAGE_SHIFT);       \
             __p < __e; __p++)

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 void host_s2_free_unlinked_table(void *addr, s8 level)
{
        kvm_pgtable_stage2_free_unlinked(&host_mmu.mm_ops, addr, level);
}

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_mmu.mm_ops = (struct kvm_pgtable_mm_ops) {
                .zalloc_pages_exact = host_s2_zalloc_pages_exact,
                .zalloc_page = host_s2_zalloc_page,
                .free_unlinked_table = host_s2_free_unlinked_table,
                .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_mmu.arch.mmu.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_mmu.arch.mmu;
        int ret;

        prepare_host_vtcr();
        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_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_mmu.pgt.pgd);
        mmu->pgt = &host_mmu.pgt;
        atomic64_set(&mmu->vmid.id, 0);

        return 0;
}

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);
        p->refcount = 1;
        p->order = 0;

        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 __apply_guest_page(void *va, size_t size,
                               void (*func)(void *addr, size_t size))
{
        size += va - PTR_ALIGN_DOWN(va, PAGE_SIZE);
        va = PTR_ALIGN_DOWN(va, PAGE_SIZE);
        size = PAGE_ALIGN(size);

        while (size) {
                size_t map_size = PAGE_SIZE;
                void *map;

                if (IS_ALIGNED((unsigned long)va, PMD_SIZE) && size >= PMD_SIZE)
                        map = hyp_fixblock_map(__hyp_pa(va), &map_size);
                else
                        map = hyp_fixmap_map(__hyp_pa(va));

                func(map, map_size);

                if (map_size == PMD_SIZE)
                        hyp_fixblock_unmap();
                else
                        hyp_fixmap_unmap();

                size -= map_size;
                va += map_size;
        }
}

static void clean_dcache_guest_page(void *va, size_t size)
{
        __apply_guest_page(va, size, __clean_dcache_guest_page);
}

static void invalidate_icache_guest_page(void *va, size_t size)
{
        __apply_guest_page(va, size, __invalidate_icache_guest_page);
}

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(mmu->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, NULL);
        guest_unlock_component(vm);
        if (ret)
                return ret;

        vm->kvm.arch.mmu.pgd_phys = __hyp_pa(vm->pgt.pgd);

        return 0;
}

void reclaim_pgtable_pages(struct pkvm_hyp_vm *vm, struct kvm_hyp_memcache *mc)
{
        struct hyp_page *page;
        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) {
                page = hyp_virt_to_page(addr);
                page->refcount = 0;
                page->order = 0;
                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_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 = mmu->vtcr;
        params->hcr_el2 |= HCR_VM;
        if (cpus_have_final_cap(ARM64_HAS_STAGE2_FWB))
                params->hcr_el2 |= HCR_FWB;

        /*
         * The CMO below not only cleans the updated params to the
         * PoC, but also provides the DSB that ensures ongoing
         * page-table walks that have started before we trapped to EL2
         * have completed.
         */
        kvm_flush_dcache_to_poc(params, sizeof(*params));

        write_sysreg_hcr(params->hcr_el2);
        __load_stage2(&host_mmu.arch.mmu, &host_mmu.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_mmu.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);
}

/*
 * Ensure the PFN range is contained within PA-range.
 *
 * This check is also robust to overflows and is therefore a requirement before
 * using a pfn/nr_pages pair from an untrusted source.
 */
static bool pfn_range_is_valid(u64 pfn, u64 nr_pages)
{
        u64 limit = BIT(kvm_phys_shift(&host_mmu.arch.mmu) - PAGE_SHIFT);

        return pfn < limit && ((limit - pfn) >= nr_pages);
}

struct kvm_mem_range {
        u64 start;
        u64 end;
};

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;
        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 reg;
                }
        }

        return NULL;
}

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 int check_range_allowed_memory(u64 start, u64 end)
{
        struct memblock_region *reg;
        struct kvm_mem_range range;

        /*
         * Callers can't check the state of a range that overlaps memory and
         * MMIO regions, so ensure [start, end[ is in the same kvm_mem_range.
         */
        reg = find_mem_range(start, &range);
        if (!is_in_mem_range(end - 1, &range))
                return -EINVAL;

        if (!reg || reg->flags & MEMBLOCK_NOMAP)
                return -EPERM;

        return 0;
}

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_mmu.pgt, start, end - start, start,
                                      prot, &host_s2_pool, 0);
}

/*
 * 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_mmu.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;
        u64 granule;
        s8 level;
        int ret;

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

        if (kvm_pte_valid(pte))
                return -EAGAIN;

        if (pte) {
                WARN_ON(addr_is_memory(addr) &&
                        get_host_state(hyp_phys_to_page(addr)) != PKVM_NOPAGE);
                return -EPERM;
        }

        for (; level <= KVM_PGTABLE_LAST_LEVEL; level++) {
                if (!kvm_level_supports_block_mapping(level))
                        continue;
                granule = kvm_granule_size(level);
                cur.start = ALIGN_DOWN(addr, granule);
                cur.end = cur.start + granule;
                if (!range_included(&cur, range) && level < KVM_PGTABLE_LAST_LEVEL)
                        continue;
                *range = cur;
                return 0;
        }

        WARN_ON(1);

        return -EINVAL;
}

int host_stage2_idmap_locked(phys_addr_t addr, u64 size,
                             enum kvm_pgtable_prot prot)
{
        return host_stage2_try(__host_stage2_idmap, addr, addr + size, prot);
}

static void __host_update_page_state(phys_addr_t addr, u64 size, enum pkvm_page_state state)
{
        for_each_hyp_page(page, addr, size)
                set_host_state(page, state);
}

int host_stage2_set_owner_locked(phys_addr_t addr, u64 size, u8 owner_id)
{
        int ret;

        if (!range_is_memory(addr, addr + size))
                return -EPERM;

        ret = host_stage2_try(kvm_pgtable_stage2_set_owner, &host_mmu.pgt,
                              addr, size, &host_s2_pool, owner_id);
        if (ret)
                return ret;

        /* Don't forget to update the vmemmap tracking for the host */
        if (owner_id == PKVM_ID_HOST)
                __host_update_page_state(addr, size, PKVM_PAGE_OWNED);
        else
                __host_update_page_state(addr, size, PKVM_NOPAGE);

        return 0;
}

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;

        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:
        host_unlock_component();

        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);
        if (!__get_fault_info(esr, &fault)) {
                /*
                 * We've presumably raced with a page-table change which caused
                 * AT to fail, try again.
                 */
                return;
        }


        /*
         * Yikes, we couldn't resolve the fault IPA. This should reinject an
         * abort into the host when we figure out how to do that.
         */
        BUG_ON(!(fault.hpfar_el2 & HPFAR_EL2_NS));
        addr = FIELD_GET(HPFAR_EL2_FIPA, fault.hpfar_el2) << 12;

        ret = host_stage2_idmap(addr);
        BUG_ON(ret && ret != -EAGAIN);
}

struct check_walk_data {
        enum pkvm_page_state    desired;
        enum pkvm_page_state    (*get_page_state)(kvm_pte_t pte, u64 addr);
};

static int __check_page_state_visitor(const struct kvm_pgtable_visit_ctx *ctx,
                                      enum kvm_pgtable_walk_flags visit)
{
        struct check_walk_data *d = ctx->arg;

        return d->get_page_state(ctx->old, ctx->addr) == 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 int __host_check_page_state_range(u64 addr, u64 size,
                                         enum pkvm_page_state state)
{
        int ret;

        ret = check_range_allowed_memory(addr, addr + size);
        if (ret)
                return ret;

        hyp_assert_lock_held(&host_mmu.lock);

        for_each_hyp_page(page, addr, size) {
                if (get_host_state(page) != state)
                        return -EPERM;
        }

        return 0;
}

static int __host_set_page_state_range(u64 addr, u64 size,
                                       enum pkvm_page_state state)
{
        if (get_host_state(hyp_phys_to_page(addr)) == PKVM_NOPAGE) {
                int ret = host_stage2_idmap_locked(addr, size, PKVM_HOST_MEM_PROT);

                if (ret)
                        return ret;
        }

        __host_update_page_state(addr, size, state);

        return 0;
}

static void __hyp_set_page_state_range(phys_addr_t phys, u64 size, enum pkvm_page_state state)
{
        for_each_hyp_page(page, phys, size)
                set_hyp_state(page, state);
}

static int __hyp_check_page_state_range(phys_addr_t phys, u64 size, enum pkvm_page_state state)
{
        for_each_hyp_page(page, phys, size) {
                if (get_hyp_state(page) != state)
                        return -EPERM;
        }

        return 0;
}

static enum pkvm_page_state guest_get_page_state(kvm_pte_t pte, u64 addr)
{
        if (!kvm_pte_valid(pte))
                return PKVM_NOPAGE;

        return pkvm_getstate(kvm_pgtable_stage2_pte_prot(pte));
}

static int __guest_check_page_state_range(struct pkvm_hyp_vm *vm, u64 addr,
                                          u64 size, enum pkvm_page_state state)
{
        struct check_walk_data d = {
                .desired        = state,
                .get_page_state = guest_get_page_state,
        };

        hyp_assert_lock_held(&vm->lock);
        return check_page_state_range(&vm->pgt, addr, size, &d);
}

int __pkvm_host_share_hyp(u64 pfn)
{
        u64 phys = hyp_pfn_to_phys(pfn);
        u64 size = PAGE_SIZE;
        int ret;

        host_lock_component();
        hyp_lock_component();

        ret = __host_check_page_state_range(phys, size, PKVM_PAGE_OWNED);
        if (ret)
                goto unlock;
        ret = __hyp_check_page_state_range(phys, size, PKVM_NOPAGE);
        if (ret)
                goto unlock;

        __hyp_set_page_state_range(phys, size, PKVM_PAGE_SHARED_BORROWED);
        WARN_ON(__host_set_page_state_range(phys, size, PKVM_PAGE_SHARED_OWNED));

unlock:
        hyp_unlock_component();
        host_unlock_component();

        return ret;
}

int __pkvm_host_unshare_hyp(u64 pfn)
{
        u64 phys = hyp_pfn_to_phys(pfn);
        u64 virt = (u64)__hyp_va(phys);
        u64 size = PAGE_SIZE;
        int ret;

        host_lock_component();
        hyp_lock_component();

        ret = __host_check_page_state_range(phys, size, PKVM_PAGE_SHARED_OWNED);
        if (ret)
                goto unlock;
        ret = __hyp_check_page_state_range(phys, size, PKVM_PAGE_SHARED_BORROWED);
        if (ret)
                goto unlock;
        if (hyp_page_count((void *)virt)) {
                ret = -EBUSY;
                goto unlock;
        }

        __hyp_set_page_state_range(phys, size, PKVM_NOPAGE);
        WARN_ON(__host_set_page_state_range(phys, size, PKVM_PAGE_OWNED));

unlock:
        hyp_unlock_component();
        host_unlock_component();

        return ret;
}

int __pkvm_host_donate_hyp(u64 pfn, u64 nr_pages)
{
        u64 phys = hyp_pfn_to_phys(pfn);
        u64 size = PAGE_SIZE * nr_pages;
        void *virt = __hyp_va(phys);
        int ret;

        if (!pfn_range_is_valid(pfn, nr_pages))
                return -EINVAL;

        host_lock_component();
        hyp_lock_component();

        ret = __host_check_page_state_range(phys, size, PKVM_PAGE_OWNED);
        if (ret)
                goto unlock;
        ret = __hyp_check_page_state_range(phys, size, PKVM_NOPAGE);
        if (ret)
                goto unlock;

        __hyp_set_page_state_range(phys, size, PKVM_PAGE_OWNED);
        WARN_ON(pkvm_create_mappings_locked(virt, virt + size, PAGE_HYP));
        WARN_ON(host_stage2_set_owner_locked(phys, size, PKVM_ID_HYP));

unlock:
        hyp_unlock_component();
        host_unlock_component();

        return ret;
}

int __pkvm_hyp_donate_host(u64 pfn, u64 nr_pages)
{
        u64 phys = hyp_pfn_to_phys(pfn);
        u64 size = PAGE_SIZE * nr_pages;
        u64 virt = (u64)__hyp_va(phys);
        int ret;

        if (!pfn_range_is_valid(pfn, nr_pages))
                return -EINVAL;

        host_lock_component();
        hyp_lock_component();

        ret = __hyp_check_page_state_range(phys, size, PKVM_PAGE_OWNED);
        if (ret)
                goto unlock;
        ret = __host_check_page_state_range(phys, size, PKVM_NOPAGE);
        if (ret)
                goto unlock;

        __hyp_set_page_state_range(phys, size, PKVM_NOPAGE);
        WARN_ON(kvm_pgtable_hyp_unmap(&pkvm_pgtable, virt, size) != size);
        WARN_ON(host_stage2_set_owner_locked(phys, size, PKVM_ID_HOST));

unlock:
        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 phys = __hyp_pa(start);
        u64 size = end - start;
        struct hyp_page *p;
        int ret;

        host_lock_component();
        hyp_lock_component();

        ret = __host_check_page_state_range(phys, size, PKVM_PAGE_SHARED_OWNED);
        if (ret)
                goto unlock;

        ret = __hyp_check_page_state_range(phys, size, PKVM_PAGE_SHARED_BORROWED);
        if (ret)
                goto unlock;

        for (cur = start; cur < end; cur += PAGE_SIZE) {
                p = hyp_virt_to_page(cur);
                hyp_page_ref_inc(p);
                if (p->refcount == 1)
                        WARN_ON(pkvm_create_mappings_locked((void *)cur,
                                                            (void *)cur + PAGE_SIZE,
                                                            PAGE_HYP));
        }

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);
        struct hyp_page *p;

        host_lock_component();
        hyp_lock_component();

        for (cur = start; cur < end; cur += PAGE_SIZE) {
                p = hyp_virt_to_page(cur);
                if (p->refcount == 1)
                        WARN_ON(kvm_pgtable_hyp_unmap(&pkvm_pgtable, cur, PAGE_SIZE) != PAGE_SIZE);
                hyp_page_ref_dec(p);
        }

        hyp_unlock_component();
        host_unlock_component();
}

int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages)
{
        u64 phys = hyp_pfn_to_phys(pfn);
        u64 size = PAGE_SIZE * nr_pages;
        int ret;

        if (!pfn_range_is_valid(pfn, nr_pages))
                return -EINVAL;

        host_lock_component();
        ret = __host_check_page_state_range(phys, size, PKVM_PAGE_OWNED);
        if (!ret)
                ret = __host_set_page_state_range(phys, size, PKVM_PAGE_SHARED_OWNED);
        host_unlock_component();

        return ret;
}

int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages)
{
        u64 phys = hyp_pfn_to_phys(pfn);
        u64 size = PAGE_SIZE * nr_pages;
        int ret;

        if (!pfn_range_is_valid(pfn, nr_pages))
                return -EINVAL;

        host_lock_component();
        ret = __host_check_page_state_range(phys, size, PKVM_PAGE_SHARED_OWNED);
        if (!ret)
                ret = __host_set_page_state_range(phys, size, PKVM_PAGE_OWNED);
        host_unlock_component();

        return ret;
}

static int __guest_check_transition_size(u64 phys, u64 ipa, u64 nr_pages, u64 *size)
{
        size_t block_size;

        if (nr_pages == 1) {
                *size = PAGE_SIZE;
                return 0;
        }

        /* We solely support second to last level huge mapping */
        block_size = kvm_granule_size(KVM_PGTABLE_LAST_LEVEL - 1);

        if (nr_pages != block_size >> PAGE_SHIFT)
                return -EINVAL;

        if (!IS_ALIGNED(phys | ipa, block_size))
                return -EINVAL;

        *size = block_size;
        return 0;
}

int __pkvm_host_share_guest(u64 pfn, u64 gfn, u64 nr_pages, struct pkvm_hyp_vcpu *vcpu,
                            enum kvm_pgtable_prot prot)
{
        struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
        u64 phys = hyp_pfn_to_phys(pfn);
        u64 ipa = hyp_pfn_to_phys(gfn);
        u64 size;
        int ret;

        if (prot & ~KVM_PGTABLE_PROT_RWX)
                return -EINVAL;

        if (!pfn_range_is_valid(pfn, nr_pages))
                return -EINVAL;

        ret = __guest_check_transition_size(phys, ipa, nr_pages, &size);
        if (ret)
                return ret;

        ret = check_range_allowed_memory(phys, phys + size);
        if (ret)
                return ret;

        host_lock_component();
        guest_lock_component(vm);

        ret = __guest_check_page_state_range(vm, ipa, size, PKVM_NOPAGE);
        if (ret)
                goto unlock;

        for_each_hyp_page(page, phys, size) {
                switch (get_host_state(page)) {
                case PKVM_PAGE_OWNED:
                        continue;
                case PKVM_PAGE_SHARED_OWNED:
                        if (page->host_share_guest_count == U32_MAX) {
                                ret = -EBUSY;
                                goto unlock;
                        }

                        /* Only host to np-guest multi-sharing is tolerated */
                        if (page->host_share_guest_count)
                                continue;

                        fallthrough;
                default:
                        ret = -EPERM;
                        goto unlock;
                }
        }

        for_each_hyp_page(page, phys, size) {
                set_host_state(page, PKVM_PAGE_SHARED_OWNED);
                page->host_share_guest_count++;
        }

        WARN_ON(kvm_pgtable_stage2_map(&vm->pgt, ipa, size, phys,
                                       pkvm_mkstate(prot, PKVM_PAGE_SHARED_BORROWED),
                                       &vcpu->vcpu.arch.pkvm_memcache, 0));

unlock:
        guest_unlock_component(vm);
        host_unlock_component();

        return ret;
}

static int __check_host_shared_guest(struct pkvm_hyp_vm *vm, u64 *__phys, u64 ipa, u64 size)
{
        enum pkvm_page_state state;
        kvm_pte_t pte;
        u64 phys;
        s8 level;
        int ret;

        ret = kvm_pgtable_get_leaf(&vm->pgt, ipa, &pte, &level);
        if (ret)
                return ret;
        if (!kvm_pte_valid(pte))
                return -ENOENT;
        if (size && kvm_granule_size(level) != size)
                return -E2BIG;

        if (!size)
                size = kvm_granule_size(level);

        state = guest_get_page_state(pte, ipa);
        if (state != PKVM_PAGE_SHARED_BORROWED)
                return -EPERM;

        phys = kvm_pte_to_phys(pte);
        ret = check_range_allowed_memory(phys, phys + size);
        if (WARN_ON(ret))
                return ret;

        for_each_hyp_page(page, phys, size) {
                if (get_host_state(page) != PKVM_PAGE_SHARED_OWNED)
                        return -EPERM;
                if (WARN_ON(!page->host_share_guest_count))
                        return -EINVAL;
        }

        *__phys = phys;

        return 0;
}

int __pkvm_host_unshare_guest(u64 gfn, u64 nr_pages, struct pkvm_hyp_vm *vm)
{
        u64 ipa = hyp_pfn_to_phys(gfn);
        u64 size, phys;
        int ret;

        ret = __guest_check_transition_size(0, ipa, nr_pages, &size);
        if (ret)
                return ret;

        host_lock_component();
        guest_lock_component(vm);

        ret = __check_host_shared_guest(vm, &phys, ipa, size);
        if (ret)
                goto unlock;

        ret = kvm_pgtable_stage2_unmap(&vm->pgt, ipa, size);
        if (ret)
                goto unlock;

        for_each_hyp_page(page, phys, size) {
                /* __check_host_shared_guest() protects against underflow */
                page->host_share_guest_count--;
                if (!page->host_share_guest_count)
                        set_host_state(page, PKVM_PAGE_OWNED);
        }

unlock:
        guest_unlock_component(vm);
        host_unlock_component();

        return ret;
}

static void assert_host_shared_guest(struct pkvm_hyp_vm *vm, u64 ipa, u64 size)
{
        u64 phys;
        int ret;

        if (!IS_ENABLED(CONFIG_NVHE_EL2_DEBUG))
                return;

        host_lock_component();
        guest_lock_component(vm);

        ret = __check_host_shared_guest(vm, &phys, ipa, size);

        guest_unlock_component(vm);
        host_unlock_component();

        WARN_ON(ret && ret != -ENOENT);
}

int __pkvm_host_relax_perms_guest(u64 gfn, struct pkvm_hyp_vcpu *vcpu, enum kvm_pgtable_prot prot)
{
        struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
        u64 ipa = hyp_pfn_to_phys(gfn);
        int ret;

        if (pkvm_hyp_vm_is_protected(vm))
                return -EPERM;

        if (prot & ~KVM_PGTABLE_PROT_RWX)
                return -EINVAL;

        assert_host_shared_guest(vm, ipa, 0);
        guest_lock_component(vm);
        ret = kvm_pgtable_stage2_relax_perms(&vm->pgt, ipa, prot, 0);
        guest_unlock_component(vm);

        return ret;
}

int __pkvm_host_wrprotect_guest(u64 gfn, u64 nr_pages, struct pkvm_hyp_vm *vm)
{
        u64 size, ipa = hyp_pfn_to_phys(gfn);
        int ret;

        if (pkvm_hyp_vm_is_protected(vm))
                return -EPERM;

        ret = __guest_check_transition_size(0, ipa, nr_pages, &size);
        if (ret)
                return ret;

        assert_host_shared_guest(vm, ipa, size);
        guest_lock_component(vm);
        ret = kvm_pgtable_stage2_wrprotect(&vm->pgt, ipa, size);
        guest_unlock_component(vm);

        return ret;
}

int __pkvm_host_test_clear_young_guest(u64 gfn, u64 nr_pages, bool mkold, struct pkvm_hyp_vm *vm)
{
        u64 size, ipa = hyp_pfn_to_phys(gfn);
        int ret;

        if (pkvm_hyp_vm_is_protected(vm))
                return -EPERM;

        ret = __guest_check_transition_size(0, ipa, nr_pages, &size);
        if (ret)
                return ret;

        assert_host_shared_guest(vm, ipa, size);
        guest_lock_component(vm);
        ret = kvm_pgtable_stage2_test_clear_young(&vm->pgt, ipa, size, mkold);
        guest_unlock_component(vm);

        return ret;
}

int __pkvm_host_mkyoung_guest(u64 gfn, struct pkvm_hyp_vcpu *vcpu)
{
        struct pkvm_hyp_vm *vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);
        u64 ipa = hyp_pfn_to_phys(gfn);

        if (pkvm_hyp_vm_is_protected(vm))
                return -EPERM;

        assert_host_shared_guest(vm, ipa, 0);
        guest_lock_component(vm);
        kvm_pgtable_stage2_mkyoung(&vm->pgt, ipa, 0);
        guest_unlock_component(vm);

        return 0;
}

#ifdef CONFIG_NVHE_EL2_DEBUG
struct pkvm_expected_state {
        enum pkvm_page_state host;
        enum pkvm_page_state hyp;
        enum pkvm_page_state guest[2]; /* [ gfn, gfn + 1 ] */
};

static struct pkvm_expected_state selftest_state;
static struct hyp_page *selftest_page;

static struct pkvm_hyp_vm selftest_vm = {
        .kvm = {
                .arch = {
                        .mmu = {
                                .arch = &selftest_vm.kvm.arch,
                                .pgt = &selftest_vm.pgt,
                        },
                },
        },
};

static struct pkvm_hyp_vcpu selftest_vcpu = {
        .vcpu = {
                .arch = {
                        .hw_mmu = &selftest_vm.kvm.arch.mmu,
                },
                .kvm = &selftest_vm.kvm,
        },
};

static void init_selftest_vm(void *virt)
{
        struct hyp_page *p = hyp_virt_to_page(virt);
        int i;

        selftest_vm.kvm.arch.mmu.vtcr = host_mmu.arch.mmu.vtcr;
        WARN_ON(kvm_guest_prepare_stage2(&selftest_vm, virt));

        for (i = 0; i < pkvm_selftest_pages(); i++) {
                if (p[i].refcount)
                        continue;
                p[i].refcount = 1;
                hyp_put_page(&selftest_vm.pool, hyp_page_to_virt(&p[i]));
        }
}

static u64 selftest_ipa(void)
{
        return BIT(selftest_vm.pgt.ia_bits - 1);
}

static void assert_page_state(void)
{
        void *virt = hyp_page_to_virt(selftest_page);
        u64 size = PAGE_SIZE << selftest_page->order;
        struct pkvm_hyp_vcpu *vcpu = &selftest_vcpu;
        u64 phys = hyp_virt_to_phys(virt);
        u64 ipa[2] = { selftest_ipa(), selftest_ipa() + PAGE_SIZE };
        struct pkvm_hyp_vm *vm;

        vm = pkvm_hyp_vcpu_to_hyp_vm(vcpu);

        host_lock_component();
        WARN_ON(__host_check_page_state_range(phys, size, selftest_state.host));
        host_unlock_component();

        hyp_lock_component();
        WARN_ON(__hyp_check_page_state_range(phys, size, selftest_state.hyp));
        hyp_unlock_component();

        guest_lock_component(&selftest_vm);
        WARN_ON(__guest_check_page_state_range(vm, ipa[0], size, selftest_state.guest[0]));
        WARN_ON(__guest_check_page_state_range(vm, ipa[1], size, selftest_state.guest[1]));
        guest_unlock_component(&selftest_vm);
}

#define assert_transition_res(res, fn, ...)             \
        do {                                            \
                WARN_ON(fn(__VA_ARGS__) != res);        \
                assert_page_state();                    \
        } while (0)

void pkvm_ownership_selftest(void *base)
{
        enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_RWX;
        void *virt = hyp_alloc_pages(&host_s2_pool, 0);
        struct pkvm_hyp_vcpu *vcpu = &selftest_vcpu;
        struct pkvm_hyp_vm *vm = &selftest_vm;
        u64 phys, size, pfn, gfn;

        WARN_ON(!virt);
        selftest_page = hyp_virt_to_page(virt);
        selftest_page->refcount = 0;
        init_selftest_vm(base);

        size = PAGE_SIZE << selftest_page->order;
        phys = hyp_virt_to_phys(virt);
        pfn = hyp_phys_to_pfn(phys);
        gfn = hyp_phys_to_pfn(selftest_ipa());

        selftest_state.host = PKVM_NOPAGE;
        selftest_state.hyp = PKVM_PAGE_OWNED;
        selftest_state.guest[0] = selftest_state.guest[1] = PKVM_NOPAGE;
        assert_page_state();
        assert_transition_res(-EPERM,   __pkvm_host_donate_hyp, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_share_hyp, pfn);
        assert_transition_res(-EPERM,   __pkvm_host_unshare_hyp, pfn);
        assert_transition_res(-EPERM,   __pkvm_host_share_ffa, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_unshare_ffa, pfn, 1);
        assert_transition_res(-EPERM,   hyp_pin_shared_mem, virt, virt + size);
        assert_transition_res(-EPERM,   __pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
        assert_transition_res(-ENOENT,  __pkvm_host_unshare_guest, gfn, 1, vm);

        selftest_state.host = PKVM_PAGE_OWNED;
        selftest_state.hyp = PKVM_NOPAGE;
        assert_transition_res(0,        __pkvm_hyp_donate_host, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_hyp_donate_host, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_unshare_hyp, pfn);
        assert_transition_res(-EPERM,   __pkvm_host_unshare_ffa, pfn, 1);
        assert_transition_res(-ENOENT,  __pkvm_host_unshare_guest, gfn, 1, vm);
        assert_transition_res(-EPERM,   hyp_pin_shared_mem, virt, virt + size);

        selftest_state.host = PKVM_PAGE_SHARED_OWNED;
        selftest_state.hyp = PKVM_PAGE_SHARED_BORROWED;
        assert_transition_res(0,        __pkvm_host_share_hyp, pfn);
        assert_transition_res(-EPERM,   __pkvm_host_share_hyp, pfn);
        assert_transition_res(-EPERM,   __pkvm_host_donate_hyp, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_share_ffa, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_hyp_donate_host, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
        assert_transition_res(-ENOENT,  __pkvm_host_unshare_guest, gfn, 1, vm);

        assert_transition_res(0,        hyp_pin_shared_mem, virt, virt + size);
        assert_transition_res(0,        hyp_pin_shared_mem, virt, virt + size);
        hyp_unpin_shared_mem(virt, virt + size);
        WARN_ON(hyp_page_count(virt) != 1);
        assert_transition_res(-EBUSY,   __pkvm_host_unshare_hyp, pfn);
        assert_transition_res(-EPERM,   __pkvm_host_share_hyp, pfn);
        assert_transition_res(-EPERM,   __pkvm_host_donate_hyp, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_share_ffa, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_hyp_donate_host, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
        assert_transition_res(-ENOENT,  __pkvm_host_unshare_guest, gfn, 1, vm);

        hyp_unpin_shared_mem(virt, virt + size);
        assert_page_state();
        WARN_ON(hyp_page_count(virt));

        selftest_state.host = PKVM_PAGE_OWNED;
        selftest_state.hyp = PKVM_NOPAGE;
        assert_transition_res(0,        __pkvm_host_unshare_hyp, pfn);

        selftest_state.host = PKVM_PAGE_SHARED_OWNED;
        selftest_state.hyp = PKVM_NOPAGE;
        assert_transition_res(0,        __pkvm_host_share_ffa, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_share_ffa, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_donate_hyp, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_share_hyp, pfn);
        assert_transition_res(-EPERM,   __pkvm_host_unshare_hyp, pfn);
        assert_transition_res(-EPERM,   __pkvm_hyp_donate_host, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
        assert_transition_res(-ENOENT,  __pkvm_host_unshare_guest, gfn, 1, vm);
        assert_transition_res(-EPERM,   hyp_pin_shared_mem, virt, virt + size);

        selftest_state.host = PKVM_PAGE_OWNED;
        selftest_state.hyp = PKVM_NOPAGE;
        assert_transition_res(0,        __pkvm_host_unshare_ffa, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_unshare_ffa, pfn, 1);

        selftest_state.host = PKVM_PAGE_SHARED_OWNED;
        selftest_state.guest[0] = PKVM_PAGE_SHARED_BORROWED;
        assert_transition_res(0,        __pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
        assert_transition_res(-EPERM,   __pkvm_host_share_guest, pfn, gfn, 1, vcpu, prot);
        assert_transition_res(-EPERM,   __pkvm_host_share_ffa, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_donate_hyp, pfn, 1);
        assert_transition_res(-EPERM,   __pkvm_host_share_hyp, pfn);
        assert_transition_res(-EPERM,   __pkvm_host_unshare_hyp, pfn);
        assert_transition_res(-EPERM,   __pkvm_hyp_donate_host, pfn, 1);
        assert_transition_res(-EPERM,   hyp_pin_shared_mem, virt, virt + size);

        selftest_state.guest[1] = PKVM_PAGE_SHARED_BORROWED;
        assert_transition_res(0,        __pkvm_host_share_guest, pfn, gfn + 1, 1, vcpu, prot);
        WARN_ON(hyp_virt_to_page(virt)->host_share_guest_count != 2);

        selftest_state.guest[0] = PKVM_NOPAGE;
        assert_transition_res(0,        __pkvm_host_unshare_guest, gfn, 1, vm);

        selftest_state.guest[1] = PKVM_NOPAGE;
        selftest_state.host = PKVM_PAGE_OWNED;
        assert_transition_res(0,        __pkvm_host_unshare_guest, gfn + 1, 1, vm);

        selftest_state.host = PKVM_NOPAGE;
        selftest_state.hyp = PKVM_PAGE_OWNED;
        assert_transition_res(0,        __pkvm_host_donate_hyp, pfn, 1);

        selftest_page->refcount = 1;
        hyp_put_page(&host_s2_pool, virt);
}
#endif