// 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);
}