/*
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; If not, see <http://www.gnu.org/licenses/>.
 */

#include <xen/cpu.h>
#include <xen/sched.h>
#include <xen/iocap.h>
#include <xen/iommu.h>
#include <xen/paging.h>
#include <xen/guest_access.h>
#include <xen/event.h>
#include <xen/softirq.h>
#include <xen/vm_event.h>
#include <xsm/xsm.h>

#include <asm/hvm/io.h>
#include <asm/io_apic.h>
#include <asm/mem_paging.h>
#include <asm/pt-contig-markers.h>
#include <asm/setup.h>

const struct iommu_init_ops *__initdata iommu_init_ops;
struct iommu_ops __ro_after_init iommu_ops;
bool __read_mostly iommu_non_coherent;
bool __initdata iommu_superpages = true;

enum iommu_intremap __read_mostly iommu_intremap = iommu_intremap_full;

#ifdef CONFIG_PV
/* Possible unfiltered LAPIC/MSI messages from untrusted sources? */
bool __read_mostly untrusted_msi;
#endif

#ifndef iommu_intpost
/*
 * In the current implementation of VT-d posted interrupts, in some extreme
 * cases, the per cpu list which saves the blocked vCPU will be very long,
 * and this will affect the interrupt latency, so let this feature off by
 * default until we find a good solution to resolve it.
 */
bool __read_mostly iommu_intpost;
#endif

void __init acpi_iommu_init(void)
{
    int ret = -ENODEV;

    if ( !iommu_enable && !iommu_intremap )
        return;

    if ( !acpi_disabled )
    {
        ret = acpi_dmar_init();

#ifndef iommu_snoop
        /*
         * As long as there's no per-domain snoop control, and as long as on
         * AMD we uniformly force coherent accesses, a possible command line
         * override should affect VT-d only.
         */
        if ( ret )
            iommu_snoop = true;
#endif

        if ( ret == -ENODEV )
            ret = acpi_ivrs_init();
    }

    if ( ret )
    {
        iommu_enable = false;
        iommu_intremap = iommu_intremap_off;
    }
}

int __init iommu_hardware_setup(void)
{
    struct IO_APIC_route_entry **ioapic_entries = NULL;
    int rc;

    if ( !iommu_init_ops )
        return -ENODEV;

    rc = scan_pci_devices();
    if ( rc )
        return rc;

    if ( !iommu_ops.init )
        iommu_ops = *iommu_init_ops->ops;
    else
        /* x2apic setup may have previously initialised the struct. */
        ASSERT(iommu_ops.init == iommu_init_ops->ops->init);

    if ( !x2apic_enabled && iommu_intremap )
    {
        /*
         * If x2APIC is enabled interrupt remapping is already enabled, so
         * there's no need to mess with the IO-APIC because the remapping
         * entries are already correctly setup by x2apic_bsp_setup.
         */
        ioapic_entries = alloc_ioapic_entries();
        if ( !ioapic_entries )
            return -ENOMEM;
        rc = save_IO_APIC_setup(ioapic_entries);
        if ( rc )
        {
            free_ioapic_entries(ioapic_entries);
            return rc;
        }

        mask_8259A();
        mask_IO_APIC_setup(ioapic_entries);
    }

    if ( !iommu_superpages )
        iommu_ops.page_sizes &= PAGE_SIZE_4K;

    rc = iommu_init_ops->setup();

    ASSERT(iommu_superpages || iommu_ops.page_sizes == PAGE_SIZE_4K);

    if ( ioapic_entries )
    {
        restore_IO_APIC_setup(ioapic_entries, rc);
        unmask_8259A();
        free_ioapic_entries(ioapic_entries);
    }

    return rc;
}

int iommu_enable_x2apic(void)
{
    if ( system_state < SYS_STATE_active )
    {
        if ( !iommu_supports_x2apic() )
            return -EOPNOTSUPP;

        iommu_ops = *iommu_init_ops->ops;
    }
    else if ( !x2apic_enabled )
        return -EOPNOTSUPP;

    if ( !iommu_ops.enable_x2apic )
        return -EOPNOTSUPP;

    return iommu_call(&iommu_ops, enable_x2apic);
}

void iommu_update_ire_from_apic(
    unsigned int apic, unsigned int pin, uint64_t rte)
{
    iommu_vcall(&iommu_ops, update_ire_from_apic, apic, pin, rte);
}

unsigned int iommu_read_apic_from_ire(unsigned int apic, unsigned int reg)
{
    return iommu_call(&iommu_ops, read_apic_from_ire, apic, reg);
}

int __init iommu_setup_hpet_msi(struct msi_desc *msi)
{
    const struct iommu_ops *ops = iommu_get_ops();
    return ops->setup_hpet_msi ? iommu_call(ops, setup_hpet_msi, msi) : -ENODEV;
}

void __hwdom_init arch_iommu_check_autotranslated_hwdom(struct domain *d)
{
    if ( !is_iommu_enabled(d) )
        panic("Presently, iommu must be enabled for PVH hardware domain\n");

    if ( !iommu_hwdom_strict )
        panic("PVH hardware domain iommu must be set in 'strict' mode\n");
}

int arch_iommu_domain_init(struct domain *d)
{
    struct domain_iommu *hd = dom_iommu(d);

    spin_lock_init(&hd->arch.mapping_lock);

    INIT_PAGE_LIST_HEAD(&hd->arch.pgtables.list);
    spin_lock_init(&hd->arch.pgtables.lock);
    INIT_LIST_HEAD(&hd->arch.identity_maps);

    return 0;
}

void arch_iommu_domain_destroy(struct domain *d)
{
    /*
     * There should be not page-tables left allocated by the time the
     * domain is destroyed. Note that arch_iommu_domain_destroy() is
     * called unconditionally, so pgtables may be uninitialized.
     */
    ASSERT(!dom_iommu(d)->platform_ops ||
           page_list_empty(&dom_iommu(d)->arch.pgtables.list));
}

struct identity_map {
    struct list_head list;
    paddr_t base, end;
    p2m_access_t access;
    unsigned int count;
};

int iommu_identity_mapping(struct domain *d, p2m_access_t p2ma,
                           paddr_t base, paddr_t end,
                           unsigned int flag)
{
    unsigned long base_pfn = base >> PAGE_SHIFT_4K;
    unsigned long end_pfn = PAGE_ALIGN_4K(end) >> PAGE_SHIFT_4K;
    struct identity_map *map;
    struct domain_iommu *hd = dom_iommu(d);

    ASSERT(pcidevs_locked());
    ASSERT(base < end);

    /*
     * No need to acquire hd->arch.mapping_lock: Both insertion and removal
     * get done while holding pcidevs_lock.
     */
    list_for_each_entry( map, &hd->arch.identity_maps, list )
    {
        if ( map->base == base && map->end == end )
        {
            int ret = 0;

            if ( p2ma != p2m_access_x )
            {
                if ( map->access != p2ma )
                    return -EADDRINUSE;
                ++map->count;
                return 0;
            }

            if ( --map->count )
                return 0;

            while ( base_pfn < end_pfn )
            {
                if ( clear_identity_p2m_entry(d, base_pfn) )
                    ret = -ENXIO;
                base_pfn++;
            }

            list_del(&map->list);
            xfree(map);

            return ret;
        }

        if ( end >= map->base && map->end >= base )
            return -EADDRINUSE;
    }

    if ( p2ma == p2m_access_x )
        return -ENOENT;

    map = xmalloc(struct identity_map);
    if ( !map )
        return -ENOMEM;

    map->base = base;
    map->end = end;
    map->access = p2ma;
    map->count = 1;

    /*
     * Insert into list ahead of mapping, so the range can be found when
     * trying to clean up.
     */
    list_add_tail(&map->list, &hd->arch.identity_maps);

    for ( ; base_pfn < end_pfn; ++base_pfn )
    {
        int err = set_identity_p2m_entry(d, base_pfn, p2ma, flag);

        if ( !err )
            continue;

        if ( (map->base >> PAGE_SHIFT_4K) == base_pfn )
        {
            list_del(&map->list);
            xfree(map);
        }
        return err;
    }

    return 0;
}

void iommu_identity_map_teardown(struct domain *d)
{
    struct domain_iommu *hd = dom_iommu(d);
    struct identity_map *map, *tmp;

    list_for_each_entry_safe ( map, tmp, &hd->arch.identity_maps, list )
    {
        list_del(&map->list);
        xfree(map);
    }
}

static unsigned int __hwdom_init hwdom_iommu_map(const struct domain *d,
                                                 unsigned long pfn,
                                                 unsigned long max_pfn)
{
    mfn_t mfn = _mfn(pfn);
    unsigned int i, type, perms = IOMMUF_readable | IOMMUF_writable;

    /*
     * Set up 1:1 mapping for dom0. Default to include only conventional RAM
     * areas and let RMRRs include needed reserved regions. When set, the
     * inclusive mapping additionally maps in every pfn up to 4GB except those
     * that fall in unusable ranges for PV Dom0.
     */
    if ( (pfn > max_pfn && !mfn_valid(mfn)) || xen_in_range(pfn) )
        return 0;

    switch ( type = page_get_ram_type(mfn) )
    {
    case RAM_TYPE_UNUSABLE:
        return 0;

    case RAM_TYPE_CONVENTIONAL:
        if ( iommu_hwdom_strict )
            return 0;
        break;

    default:
        if ( type & RAM_TYPE_RESERVED )
        {
            if ( !iommu_hwdom_inclusive && !iommu_hwdom_reserved )
                perms = 0;
        }
        else if ( is_hvm_domain(d) )
            return 0;
        else if ( !iommu_hwdom_inclusive || pfn > max_pfn )
            perms = 0;
    }

    /* Check that it doesn't overlap with the Interrupt Address Range. */
    if ( pfn >= 0xfee00 && pfn <= 0xfeeff )
        return 0;
    /* ... or the IO-APIC */
    if ( has_vioapic(d) )
    {
        for ( i = 0; i < d->arch.hvm.nr_vioapics; i++ )
            if ( pfn == PFN_DOWN(domain_vioapic(d, i)->base_address) )
                return 0;
    }
    else if ( is_pv_domain(d) )
    {
        /*
         * Be consistent with CPU mappings: Dom0 is permitted to establish r/o
         * ones there (also for e.g. HPET in certain cases), so it should also
         * have such established for IOMMUs.
         */
        if ( iomem_access_permitted(d, pfn, pfn) &&
             rangeset_contains_singleton(mmio_ro_ranges, pfn) )
            perms = IOMMUF_readable;
    }
    /*
     * ... or the PCIe MCFG regions.
     * TODO: runtime added MMCFG regions are not checked to make sure they
     * don't overlap with already mapped regions, thus preventing trapping.
     */
    if ( has_vpci(d) && vpci_is_mmcfg_address(d, pfn_to_paddr(pfn)) )
        return 0;

    return perms;
}

void __hwdom_init arch_iommu_hwdom_init(struct domain *d)
{
    unsigned long i, top, max_pfn, start, count;
    unsigned int flush_flags = 0, start_perms = 0;

    BUG_ON(!is_hardware_domain(d));

    /* Reserved IOMMU mappings are enabled by default. */
    if ( iommu_hwdom_reserved == -1 )
        iommu_hwdom_reserved = 1;

    if ( iommu_hwdom_inclusive )
    {
        printk(XENLOG_WARNING
               "IOMMU inclusive mappings are deprecated and will be removed in future versions\n");

        if ( !is_pv_domain(d) )
        {
            printk(XENLOG_WARNING
                   "IOMMU inclusive mappings are only supported on PV Dom0\n");
            iommu_hwdom_inclusive = false;
        }
    }

    if ( iommu_hwdom_passthrough )
        return;

    max_pfn = (GB(4) >> PAGE_SHIFT) - 1;
    top = max(max_pdx, pfn_to_pdx(max_pfn) + 1);

    for ( i = 0, start = 0, count = 0; i < top; )
    {
        unsigned long pfn = pdx_to_pfn(i);
        unsigned int perms = hwdom_iommu_map(d, pfn, max_pfn);

        if ( !perms )
            /* nothing */;
        else if ( paging_mode_translate(d) )
        {
            int rc;

            rc = p2m_add_identity_entry(d, pfn,
                                        perms & IOMMUF_writable ? p2m_access_rw
                                                                : p2m_access_r,
                                        0);
            if ( rc )
                printk(XENLOG_WARNING
                       "%pd: identity mapping of %lx failed: %d\n",
                       d, pfn, rc);
        }
        else if ( pfn != start + count || perms != start_perms )
        {
            long rc;

        commit:
            while ( (rc = iommu_map(d, _dfn(start), _mfn(start), count,
                                    start_perms | IOMMUF_preempt,
                                    &flush_flags)) > 0 )
            {
                start += rc;
                count -= rc;
                process_pending_softirqs();
            }
            if ( rc )
                printk(XENLOG_WARNING
                       "%pd: IOMMU identity mapping of [%lx,%lx) failed: %ld\n",
                       d, start, start + count, rc);
            start = pfn;
            count = 1;
            start_perms = perms;
        }
        else
            ++count;

        if ( !(++i & 0xfffff) )
            process_pending_softirqs();

        if ( i == top && count )
            goto commit;
    }

    /* Use if to avoid compiler warning */
    if ( iommu_iotlb_flush_all(d, flush_flags) )
        return;
}

void arch_pci_init_pdev(struct pci_dev *pdev)
{
    pdev->arch.pseudo_domid = DOMID_INVALID;
}

unsigned long *__init iommu_init_domid(domid_t reserve)
{
    unsigned long *map;

    if ( !iommu_quarantine )
        return ZERO_BLOCK_PTR;

    BUILD_BUG_ON(DOMID_MASK * 2U >= UINT16_MAX);

    map = xzalloc_array(unsigned long, BITS_TO_LONGS(UINT16_MAX - DOMID_MASK));
    if ( map && reserve != DOMID_INVALID )
    {
        ASSERT(reserve > DOMID_MASK);
        __set_bit(reserve & DOMID_MASK, map);
    }

    return map;
}

domid_t iommu_alloc_domid(unsigned long *map)
{
    /*
     * This is used uniformly across all IOMMUs, such that on typical
     * systems we wouldn't re-use the same ID very quickly (perhaps never).
     */
    static unsigned int start;
    unsigned int idx = find_next_zero_bit(map, UINT16_MAX - DOMID_MASK, start);

    ASSERT(pcidevs_locked());

    if ( idx >= UINT16_MAX - DOMID_MASK )
        idx = find_first_zero_bit(map, UINT16_MAX - DOMID_MASK);
    if ( idx >= UINT16_MAX - DOMID_MASK )
        return DOMID_INVALID;

    __set_bit(idx, map);

    start = idx + 1;

    return idx | (DOMID_MASK + 1);
}

void iommu_free_domid(domid_t domid, unsigned long *map)
{
    ASSERT(pcidevs_locked());

    if ( domid == DOMID_INVALID )
        return;

    ASSERT(domid > DOMID_MASK);

    if ( !__test_and_clear_bit(domid & DOMID_MASK, map) )
        BUG();
}

int iommu_free_pgtables(struct domain *d)
{
    struct domain_iommu *hd = dom_iommu(d);
    struct page_info *pg;
    unsigned int done = 0;

    if ( !is_iommu_enabled(d) )
        return 0;

    /* After this barrier, no new IOMMU mappings can be inserted. */
    spin_barrier(&hd->arch.mapping_lock);

    /*
     * Pages will be moved to the free list below. So we want to
     * clear the root page-table to avoid any potential use after-free.
     */
    iommu_vcall(hd->platform_ops, clear_root_pgtable, d);

    while ( (pg = page_list_remove_head(&hd->arch.pgtables.list)) )
    {
        free_domheap_page(pg);

        if ( !(++done & 0xff) && general_preempt_check() )
            return -ERESTART;
    }

    return 0;
}

struct page_info *iommu_alloc_pgtable(struct domain_iommu *hd,
                                      uint64_t contig_mask)
{
    unsigned int memflags = 0;
    struct page_info *pg;
    uint64_t *p;

#ifdef CONFIG_NUMA
    if ( hd->node != NUMA_NO_NODE )
        memflags = MEMF_node(hd->node);
#endif

    pg = alloc_domheap_page(NULL, memflags);
    if ( !pg )
        return NULL;

    p = __map_domain_page(pg);

    if ( contig_mask )
    {
        /* See pt-contig-markers.h for a description of the marker scheme. */
        unsigned int i, shift = find_first_set_bit(contig_mask);

        ASSERT((CONTIG_LEVEL_SHIFT & (contig_mask >> shift)) == CONTIG_LEVEL_SHIFT);

        p[0] = (CONTIG_LEVEL_SHIFT + 0ULL) << shift;
        p[1] = 0;
        p[2] = 1ULL << shift;
        p[3] = 0;

        for ( i = 4; i < PAGE_SIZE / sizeof(*p); i += 4 )
        {
            p[i + 0] = (find_first_set_bit(i) + 0ULL) << shift;
            p[i + 1] = 0;
            p[i + 2] = 1ULL << shift;
            p[i + 3] = 0;
        }
    }
    else
        clear_page(p);

    iommu_sync_cache(p, PAGE_SIZE);

    unmap_domain_page(p);

    spin_lock(&hd->arch.pgtables.lock);
    page_list_add(pg, &hd->arch.pgtables.list);
    spin_unlock(&hd->arch.pgtables.lock);

    return pg;
}

/*
 * Intermediate page tables which get replaced by large pages may only be
 * freed after a suitable IOTLB flush. Hence such pages get queued on a
 * per-CPU list, with a per-CPU tasklet processing the list on the assumption
 * that the necessary IOTLB flush will have occurred by the time tasklets get
 * to run. (List and tasklet being per-CPU has the benefit of accesses not
 * requiring any locking.)
 */
static DEFINE_PER_CPU(struct page_list_head, free_pgt_list);
static DEFINE_PER_CPU(struct tasklet, free_pgt_tasklet);

static void cf_check free_queued_pgtables(void *arg)
{
    struct page_list_head *list = arg;
    struct page_info *pg;
    unsigned int done = 0;

    ASSERT(list == &this_cpu(free_pgt_list));

    while ( (pg = page_list_remove_head(list)) )
    {
        free_domheap_page(pg);

        /*
         * Just to be on the safe side, check for processing softirqs every
         * once in a while.  Generally it is expected that parties queuing
         * pages for freeing will find a need for preemption before too many
         * pages can be queued.  Granularity of checking is somewhat arbitrary.
         */
        if ( !(++done & 0x1ff) )
             process_pending_softirqs();
    }
}

void iommu_queue_free_pgtable(struct domain_iommu *hd, struct page_info *pg)
{
    unsigned int cpu = smp_processor_id();

    spin_lock(&hd->arch.pgtables.lock);
    page_list_del(pg, &hd->arch.pgtables.list);
    spin_unlock(&hd->arch.pgtables.lock);

    page_list_add_tail(pg, &per_cpu(free_pgt_list, cpu));

    tasklet_schedule(&per_cpu(free_pgt_tasklet, cpu));
}

static int cf_check cpu_callback(
    struct notifier_block *nfb, unsigned long action, void *hcpu)
{
    unsigned int cpu = (unsigned long)hcpu;
    struct page_list_head *list = &per_cpu(free_pgt_list, cpu);
    struct tasklet *tasklet = &per_cpu(free_pgt_tasklet, cpu);

    switch ( action )
    {
    case CPU_DOWN_PREPARE:
        tasklet_kill(tasklet);
        break;

    case CPU_DEAD:
        if ( !page_list_empty(list) )
        {
            page_list_splice(list, &this_cpu(free_pgt_list));
            INIT_PAGE_LIST_HEAD(list);
            tasklet_schedule(&this_cpu(free_pgt_tasklet));
        }
        break;

    case CPU_UP_PREPARE:
        INIT_PAGE_LIST_HEAD(list);
        fallthrough;
    case CPU_DOWN_FAILED:
        tasklet_init(tasklet, free_queued_pgtables, list);
        if ( !page_list_empty(list) )
            tasklet_schedule(tasklet);
        break;
    }

    return NOTIFY_DONE;
}

static struct notifier_block cpu_nfb = {
    .notifier_call = cpu_callback,
};

static int __init cf_check bsp_init(void)
{
    if ( iommu_enabled )
    {
        cpu_callback(&cpu_nfb, CPU_UP_PREPARE,
                     (void *)(unsigned long)smp_processor_id());
        register_cpu_notifier(&cpu_nfb);
    }

    return 0;
}
presmp_initcall(bsp_init);

bool arch_iommu_use_permitted(const struct domain *d)
{
    /*
     * Prevent device assign if mem paging, mem sharing or log-dirty
     * have been enabled for this domain, or if PoD is still in active use.
     */
    return d == dom_io ||
           (likely(!mem_sharing_enabled(d)) &&
            likely(!mem_paging_enabled(d)) &&
            likely(!p2m_pod_active(d)) &&
            likely(!p2m_is_global_logdirty(d)));
}

static int __init cf_check adjust_irq_affinities(void)
{
    iommu_adjust_irq_affinities();

    return 0;
}
__initcall(adjust_irq_affinities);

/*
 * Local variables:
 * mode: C
 * c-file-style: "BSD"
 * c-basic-offset: 4
 * indent-tabs-mode: nil
 * End:
 */
