mem_protect.c

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// 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_NOFWB | 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);
}
 
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 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(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,
                    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_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;
 
    /*
     * 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(params->hcr_el2, 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);
}
 
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 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)
{
    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_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;
    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)
        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_LAST_LEVEL) &&
            !(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)
{
    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)
{
    return host_stage2_try(kvm_pgtable_stage2_set_owner, &host_mmu.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;
 
    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);
    BUG_ON(!__get_fault_info(esr, &fault));
 
    addr = (fault.hpfar_el2 & HPFAR_MASK) << 8;
    ret = host_stage2_idmap(addr);
    BUG_ON(ret && ret != -EAGAIN);
}
 
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;
            struct {
                u64 completer_addr;
            } hyp;
        };
    } 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 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, 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 enum pkvm_page_state host_get_page_state(kvm_pte_t pte, u64 addr)
{
    if (!addr_is_allowed_memory(addr))
        return PKVM_NOPAGE;
 
    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_mmu.lock);
    return check_page_state_range(&host_mmu.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 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, u64 addr)
{
    if (!kvm_pte_valid(pte))
        return PKVM_NOPAGE;
 
    return pkvm_getstate(kvm_pgtable_hyp_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 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) ||
         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 (tx->initiator.id == PKVM_ID_HOST && hyp_page_count((void *)addr))
        return -EBUSY;
 
    if (__hyp_ack_skip_pgtable_check(tx))
        return 0;
 
    return __hyp_check_page_state_range(addr, size,
                        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)
{
    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 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;
    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;
    }
 
    if (ret)
        return ret;
 
    switch (tx->completer.id) {
    case PKVM_ID_HYP:
        ret = hyp_ack_share(completer_addr, tx, share->completer_prot);
        break;
    case PKVM_ID_FFA:
        /*
         * We only check the host; the secure side will check the other
         * end when we forward the FFA call.
         */
        ret = 0;
        break;
    default:
        ret = -EINVAL;
    }
 
    return ret;
}
 
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;
    }
 
    if (ret)
        return ret;
 
    switch (tx->completer.id) {
    case PKVM_ID_HYP:
        ret = hyp_complete_share(completer_addr, tx, share->completer_prot);
        break;
    case PKVM_ID_FFA:
        /*
         * We're not responsible for any secure page-tables, so there's
         * nothing to do here.
         */
        ret = 0;
        break;
    default:
        ret = -EINVAL;
    }
 
    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;
 
    ret = check_share(share);
    if (ret)
        return ret;
 
    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;
    case PKVM_ID_FFA:
        /* See check_share() */
        ret = 0;
        break;
    default:
        ret = -EINVAL;
    }
 
    return ret;
}
 
static int __do_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_initiate_unshare(&completer_addr, tx);
        break;
    default:
        ret = -EINVAL;
    }
 
    if (ret)
        return ret;
 
    switch (tx->completer.id) {
    case PKVM_ID_HYP:
        ret = hyp_complete_unshare(completer_addr, tx);
        break;
    case PKVM_ID_FFA:
        /* See __do_share() */
        ret = 0;
        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));
}
 
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;
    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;
}
 
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();
}
 
int __pkvm_host_share_ffa(u64 pfn, u64 nr_pages)
{
    int ret;
    struct pkvm_mem_share share = {
        .tx = {
            .nr_pages   = nr_pages,
            .initiator  = {
                .id = PKVM_ID_HOST,
                .addr   = hyp_pfn_to_phys(pfn),
            },
            .completer  = {
                .id = PKVM_ID_FFA,
            },
        },
    };
 
    host_lock_component();
    ret = do_share(&share);
    host_unlock_component();
 
    return ret;
}
 
int __pkvm_host_unshare_ffa(u64 pfn, u64 nr_pages)
{
    int ret;
    struct pkvm_mem_share share = {
        .tx = {
            .nr_pages   = nr_pages,
            .initiator  = {
                .id = PKVM_ID_HOST,
                .addr   = hyp_pfn_to_phys(pfn),
            },
            .completer  = {
                .id = PKVM_ID_FFA,
            },
        },
    };
 
    host_lock_component();
    ret = do_unshare(&share);
    host_unlock_component();
 
    return ret;
}