// SPDX-License-Identifier: GPL-2.0-only
/*
 * GICv3 ITS emulation
 *
 * Copyright (C) 2015,2016 ARM Ltd.
 * Author: Andre Przywara <andre.przywara@arm.com>
 */

#include <linux/cpu.h>
#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/uaccess.h>
#include <linux/list_sort.h>

#include <linux/irqchip/arm-gic-v3.h>

#include <asm/kvm_emulate.h>
#include <asm/kvm_arm.h>
#include <asm/kvm_mmu.h>

#include "vgic.h"
#include "vgic-mmio.h"

static int vgic_its_save_tables_v0(struct vgic_its *its);
static int vgic_its_restore_tables_v0(struct vgic_its *its);
static int vgic_its_commit_v0(struct vgic_its *its);
static int update_lpi_config(struct kvm *kvm, struct vgic_irq *irq,
                             struct kvm_vcpu *filter_vcpu, bool needs_inv);

/*
 * Creates a new (reference to a) struct vgic_irq for a given LPI.
 * If this LPI is already mapped on another ITS, we increase its refcount
 * and return a pointer to the existing structure.
 * If this is a "new" LPI, we allocate and initialize a new struct vgic_irq.
 * This function returns a pointer to the _unlocked_ structure.
 */
static struct vgic_irq *vgic_add_lpi(struct kvm *kvm, u32 intid,
                                     struct kvm_vcpu *vcpu)
{
        struct vgic_dist *dist = &kvm->arch.vgic;
        struct vgic_irq *irq = vgic_get_irq(kvm, NULL, intid), *oldirq;
        unsigned long flags;
        int ret;

        /* In this case there is no put, since we keep the reference. */
        if (irq)
                return irq;

        irq = kzalloc(sizeof(struct vgic_irq), GFP_KERNEL);
        if (!irq)
                return ERR_PTR(-ENOMEM);

        INIT_LIST_HEAD(&irq->lpi_list);
        INIT_LIST_HEAD(&irq->ap_list);
        raw_spin_lock_init(&irq->irq_lock);

        irq->config = VGIC_CONFIG_EDGE;
        kref_init(&irq->refcount);
        irq->intid = intid;
        irq->target_vcpu = vcpu;
        irq->group = 1;

        raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);

        /*
         * There could be a race with another vgic_add_lpi(), so we need to
         * check that we don't add a second list entry with the same LPI.
         */
        list_for_each_entry(oldirq, &dist->lpi_list_head, lpi_list) {
                if (oldirq->intid != intid)
                        continue;

                /* Someone was faster with adding this LPI, lets use that. */
                kfree(irq);
                irq = oldirq;

                /*
                 * This increases the refcount, the caller is expected to
                 * call vgic_put_irq() on the returned pointer once it's
                 * finished with the IRQ.
                 */
                vgic_get_irq_kref(irq);

                goto out_unlock;
        }

        list_add_tail(&irq->lpi_list, &dist->lpi_list_head);
        dist->lpi_list_count++;

out_unlock:
        raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);

        /*
         * We "cache" the configuration table entries in our struct vgic_irq's.
         * However we only have those structs for mapped IRQs, so we read in
         * the respective config data from memory here upon mapping the LPI.
         *
         * Should any of these fail, behave as if we couldn't create the LPI
         * by dropping the refcount and returning the error.
         */
        ret = update_lpi_config(kvm, irq, NULL, false);
        if (ret) {
                vgic_put_irq(kvm, irq);
                return ERR_PTR(ret);
        }

        ret = vgic_v3_lpi_sync_pending_status(kvm, irq);
        if (ret) {
                vgic_put_irq(kvm, irq);
                return ERR_PTR(ret);
        }

        return irq;
}

struct its_device {
        struct list_head dev_list;

        /* the head for the list of ITTEs */
        struct list_head itt_head;
        u32 num_eventid_bits;
        gpa_t itt_addr;
        u32 device_id;
};

#define COLLECTION_NOT_MAPPED ((u32)~0)

struct its_collection {
        struct list_head coll_list;

        u32 collection_id;
        u32 target_addr;
};

#define its_is_collection_mapped(coll) ((coll) && \
                                ((coll)->target_addr != COLLECTION_NOT_MAPPED))

struct its_ite {
        struct list_head ite_list;

        struct vgic_irq *irq;
        struct its_collection *collection;
        u32 event_id;
};

struct vgic_translation_cache_entry {
        struct list_head        entry;
        phys_addr_t             db;
        u32                     devid;
        u32                     eventid;
        struct vgic_irq         *irq;
};

/**
 * struct vgic_its_abi - ITS abi ops and settings
 * @cte_esz: collection table entry size
 * @dte_esz: device table entry size
 * @ite_esz: interrupt translation table entry size
 * @save tables: save the ITS tables into guest RAM
 * @restore_tables: restore the ITS internal structs from tables
 *  stored in guest RAM
 * @commit: initialize the registers which expose the ABI settings,
 *  especially the entry sizes
 */
struct vgic_its_abi {
        int cte_esz;
        int dte_esz;
        int ite_esz;
        int (*save_tables)(struct vgic_its *its);
        int (*restore_tables)(struct vgic_its *its);
        int (*commit)(struct vgic_its *its);
};

#define ABI_0_ESZ       8
#define ESZ_MAX         ABI_0_ESZ

static const struct vgic_its_abi its_table_abi_versions[] = {
        [0] = {
         .cte_esz = ABI_0_ESZ,
         .dte_esz = ABI_0_ESZ,
         .ite_esz = ABI_0_ESZ,
         .save_tables = vgic_its_save_tables_v0,
         .restore_tables = vgic_its_restore_tables_v0,
         .commit = vgic_its_commit_v0,
        },
};

#define NR_ITS_ABIS     ARRAY_SIZE(its_table_abi_versions)

inline const struct vgic_its_abi *vgic_its_get_abi(struct vgic_its *its)
{
        return &its_table_abi_versions[its->abi_rev];
}

static int vgic_its_set_abi(struct vgic_its *its, u32 rev)
{
        const struct vgic_its_abi *abi;

        its->abi_rev = rev;
        abi = vgic_its_get_abi(its);
        return abi->commit(its);
}

/*
 * Find and returns a device in the device table for an ITS.
 * Must be called with the its_lock mutex held.
 */
static struct its_device *find_its_device(struct vgic_its *its, u32 device_id)
{
        struct its_device *device;

        list_for_each_entry(device, &its->device_list, dev_list)
                if (device_id == device->device_id)
                        return device;

        return NULL;
}

/*
 * Find and returns an interrupt translation table entry (ITTE) for a given
 * Device ID/Event ID pair on an ITS.
 * Must be called with the its_lock mutex held.
 */
static struct its_ite *find_ite(struct vgic_its *its, u32 device_id,
                                  u32 event_id)
{
        struct its_device *device;
        struct its_ite *ite;

        device = find_its_device(its, device_id);
        if (device == NULL)
                return NULL;

        list_for_each_entry(ite, &device->itt_head, ite_list)
                if (ite->event_id == event_id)
                        return ite;

        return NULL;
}

/* To be used as an iterator this macro misses the enclosing parentheses */
#define for_each_lpi_its(dev, ite, its) \
        list_for_each_entry(dev, &(its)->device_list, dev_list) \
                list_for_each_entry(ite, &(dev)->itt_head, ite_list)

#define GIC_LPI_OFFSET 8192

#define VITS_TYPER_IDBITS 16
#define VITS_TYPER_DEVBITS 16
#define VITS_DTE_MAX_DEVID_OFFSET       (BIT(14) - 1)
#define VITS_ITE_MAX_EVENTID_OFFSET     (BIT(16) - 1)

/*
 * Finds and returns a collection in the ITS collection table.
 * Must be called with the its_lock mutex held.
 */
static struct its_collection *find_collection(struct vgic_its *its, int coll_id)
{
        struct its_collection *collection;

        list_for_each_entry(collection, &its->collection_list, coll_list) {
                if (coll_id == collection->collection_id)
                        return collection;
        }

        return NULL;
}

#define LPI_PROP_ENABLE_BIT(p)  ((p) & LPI_PROP_ENABLED)
#define LPI_PROP_PRIORITY(p)    ((p) & 0xfc)

/*
 * Reads the configuration data for a given LPI from guest memory and
 * updates the fields in struct vgic_irq.
 * If filter_vcpu is not NULL, applies only if the IRQ is targeting this
 * VCPU. Unconditionally applies if filter_vcpu is NULL.
 */
static int update_lpi_config(struct kvm *kvm, struct vgic_irq *irq,
                             struct kvm_vcpu *filter_vcpu, bool needs_inv)
{
        u64 propbase = GICR_PROPBASER_ADDRESS(kvm->arch.vgic.propbaser);
        u8 prop;
        int ret;
        unsigned long flags;

        ret = kvm_read_guest_lock(kvm, propbase + irq->intid - GIC_LPI_OFFSET,
                                  &prop, 1);

        if (ret)
                return ret;

        raw_spin_lock_irqsave(&irq->irq_lock, flags);

        if (!filter_vcpu || filter_vcpu == irq->target_vcpu) {
                irq->priority = LPI_PROP_PRIORITY(prop);
                irq->enabled = LPI_PROP_ENABLE_BIT(prop);

                if (!irq->hw) {
                        vgic_queue_irq_unlock(kvm, irq, flags);
                        return 0;
                }
        }

        raw_spin_unlock_irqrestore(&irq->irq_lock, flags);

        if (irq->hw)
                return its_prop_update_vlpi(irq->host_irq, prop, needs_inv);

        return 0;
}

/*
 * Create a snapshot of the current LPIs targeting @vcpu, so that we can
 * enumerate those LPIs without holding any lock.
 * Returns their number and puts the kmalloc'ed array into intid_ptr.
 */
int vgic_copy_lpi_list(struct kvm *kvm, struct kvm_vcpu *vcpu, u32 **intid_ptr)
{
        struct vgic_dist *dist = &kvm->arch.vgic;
        struct vgic_irq *irq;
        unsigned long flags;
        u32 *intids;
        int irq_count, i = 0;

        /*
         * There is an obvious race between allocating the array and LPIs
         * being mapped/unmapped. If we ended up here as a result of a
         * command, we're safe (locks are held, preventing another
         * command). If coming from another path (such as enabling LPIs),
         * we must be careful not to overrun the array.
         */
        irq_count = READ_ONCE(dist->lpi_list_count);
        intids = kmalloc_array(irq_count, sizeof(intids[0]), GFP_KERNEL);
        if (!intids)
                return -ENOMEM;

        raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
        list_for_each_entry(irq, &dist->lpi_list_head, lpi_list) {
                if (i == irq_count)
                        break;
                /* We don't need to "get" the IRQ, as we hold the list lock. */
                if (vcpu && irq->target_vcpu != vcpu)
                        continue;
                intids[i++] = irq->intid;
        }
        raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);

        *intid_ptr = intids;
        return i;
}

static int update_affinity(struct vgic_irq *irq, struct kvm_vcpu *vcpu)
{
        int ret = 0;
        unsigned long flags;

        raw_spin_lock_irqsave(&irq->irq_lock, flags);
        irq->target_vcpu = vcpu;
        raw_spin_unlock_irqrestore(&irq->irq_lock, flags);

        if (irq->hw) {
                struct its_vlpi_map map;

                ret = its_get_vlpi(irq->host_irq, &map);
                if (ret)
                        return ret;

                if (map.vpe)
                        atomic_dec(&map.vpe->vlpi_count);
                map.vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
                atomic_inc(&map.vpe->vlpi_count);

                ret = its_map_vlpi(irq->host_irq, &map);
        }

        return ret;
}

/*
 * Promotes the ITS view of affinity of an ITTE (which redistributor this LPI
 * is targeting) to the VGIC's view, which deals with target VCPUs.
 * Needs to be called whenever either the collection for a LPIs has
 * changed or the collection itself got retargeted.
 */
static void update_affinity_ite(struct kvm *kvm, struct its_ite *ite)
{
        struct kvm_vcpu *vcpu;

        if (!its_is_collection_mapped(ite->collection))
                return;

        vcpu = kvm_get_vcpu(kvm, ite->collection->target_addr);
        update_affinity(ite->irq, vcpu);
}

/*
 * Updates the target VCPU for every LPI targeting this collection.
 * Must be called with the its_lock mutex held.
 */
static void update_affinity_collection(struct kvm *kvm, struct vgic_its *its,
                                       struct its_collection *coll)
{
        struct its_device *device;
        struct its_ite *ite;

        for_each_lpi_its(device, ite, its) {
                if (!ite->collection || coll != ite->collection)
                        continue;

                update_affinity_ite(kvm, ite);
        }
}

static u32 max_lpis_propbaser(u64 propbaser)
{
        int nr_idbits = (propbaser & 0x1f) + 1;

        return 1U << min(nr_idbits, INTERRUPT_ID_BITS_ITS);
}

/*
 * Sync the pending table pending bit of LPIs targeting @vcpu
 * with our own data structures. This relies on the LPI being
 * mapped before.
 */
static int its_sync_lpi_pending_table(struct kvm_vcpu *vcpu)
{
        gpa_t pendbase = GICR_PENDBASER_ADDRESS(vcpu->arch.vgic_cpu.pendbaser);
        struct vgic_irq *irq;
        int last_byte_offset = -1;
        int ret = 0;
        u32 *intids;
        int nr_irqs, i;
        unsigned long flags;
        u8 pendmask;

        nr_irqs = vgic_copy_lpi_list(vcpu->kvm, vcpu, &intids);
        if (nr_irqs < 0)
                return nr_irqs;

        for (i = 0; i < nr_irqs; i++) {
                int byte_offset, bit_nr;

                byte_offset = intids[i] / BITS_PER_BYTE;
                bit_nr = intids[i] % BITS_PER_BYTE;

                /*
                 * For contiguously allocated LPIs chances are we just read
                 * this very same byte in the last iteration. Reuse that.
                 */
                if (byte_offset != last_byte_offset) {
                        ret = kvm_read_guest_lock(vcpu->kvm,
                                                  pendbase + byte_offset,
                                                  &pendmask, 1);
                        if (ret) {
                                kfree(intids);
                                return ret;
                        }
                        last_byte_offset = byte_offset;
                }

                irq = vgic_get_irq(vcpu->kvm, NULL, intids[i]);
                raw_spin_lock_irqsave(&irq->irq_lock, flags);
                irq->pending_latch = pendmask & (1U << bit_nr);
                vgic_queue_irq_unlock(vcpu->kvm, irq, flags);
                vgic_put_irq(vcpu->kvm, irq);
        }

        kfree(intids);

        return ret;
}

static unsigned long vgic_mmio_read_its_typer(struct kvm *kvm,
                                              struct vgic_its *its,
                                              gpa_t addr, unsigned int len)
{
        const struct vgic_its_abi *abi = vgic_its_get_abi(its);
        u64 reg = GITS_TYPER_PLPIS;

        /*
         * We use linear CPU numbers for redistributor addressing,
         * so GITS_TYPER.PTA is 0.
         * Also we force all PROPBASER registers to be the same, so
         * CommonLPIAff is 0 as well.
         * To avoid memory waste in the guest, we keep the number of IDBits and
         * DevBits low - as least for the time being.
         */
        reg |= GIC_ENCODE_SZ(VITS_TYPER_DEVBITS, 5) << GITS_TYPER_DEVBITS_SHIFT;
        reg |= GIC_ENCODE_SZ(VITS_TYPER_IDBITS, 5) << GITS_TYPER_IDBITS_SHIFT;
        reg |= GIC_ENCODE_SZ(abi->ite_esz, 4) << GITS_TYPER_ITT_ENTRY_SIZE_SHIFT;

        return extract_bytes(reg, addr & 7, len);
}

static unsigned long vgic_mmio_read_its_iidr(struct kvm *kvm,
                                             struct vgic_its *its,
                                             gpa_t addr, unsigned int len)
{
        u32 val;

        val = (its->abi_rev << GITS_IIDR_REV_SHIFT) & GITS_IIDR_REV_MASK;
        val |= (PRODUCT_ID_KVM << GITS_IIDR_PRODUCTID_SHIFT) | IMPLEMENTER_ARM;
        return val;
}

static int vgic_mmio_uaccess_write_its_iidr(struct kvm *kvm,
                                            struct vgic_its *its,
                                            gpa_t addr, unsigned int len,
                                            unsigned long val)
{
        u32 rev = GITS_IIDR_REV(val);

        if (rev >= NR_ITS_ABIS)
                return -EINVAL;
        return vgic_its_set_abi(its, rev);
}

static unsigned long vgic_mmio_read_its_idregs(struct kvm *kvm,
                                               struct vgic_its *its,
                                               gpa_t addr, unsigned int len)
{
        switch (addr & 0xffff) {
        case GITS_PIDR0:
                return 0x92;    /* part number, bits[7:0] */
        case GITS_PIDR1:
                return 0xb4;    /* part number, bits[11:8] */
        case GITS_PIDR2:
                return GIC_PIDR2_ARCH_GICv3 | 0x0b;
        case GITS_PIDR4:
                return 0x40;    /* This is a 64K software visible page */
        /* The following are the ID registers for (any) GIC. */
        case GITS_CIDR0:
                return 0x0d;
        case GITS_CIDR1:
                return 0xf0;
        case GITS_CIDR2:
                return 0x05;
        case GITS_CIDR3:
                return 0xb1;
        }

        return 0;
}

static struct vgic_irq *__vgic_its_check_cache(struct vgic_dist *dist,
                                               phys_addr_t db,
                                               u32 devid, u32 eventid)
{
        struct vgic_translation_cache_entry *cte;

        list_for_each_entry(cte, &dist->lpi_translation_cache, entry) {
                /*
                 * If we hit a NULL entry, there is nothing after this
                 * point.
                 */
                if (!cte->irq)
                        break;

                if (cte->db != db || cte->devid != devid ||
                    cte->eventid != eventid)
                        continue;

                /*
                 * Move this entry to the head, as it is the most
                 * recently used.
                 */
                if (!list_is_first(&cte->entry, &dist->lpi_translation_cache))
                        list_move(&cte->entry, &dist->lpi_translation_cache);

                return cte->irq;
        }

        return NULL;
}

static struct vgic_irq *vgic_its_check_cache(struct kvm *kvm, phys_addr_t db,
                                             u32 devid, u32 eventid)
{
        struct vgic_dist *dist = &kvm->arch.vgic;
        struct vgic_irq *irq;
        unsigned long flags;

        raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);
        irq = __vgic_its_check_cache(dist, db, devid, eventid);
        raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);

        return irq;
}

static void vgic_its_cache_translation(struct kvm *kvm, struct vgic_its *its,
                                       u32 devid, u32 eventid,
                                       struct vgic_irq *irq)
{
        struct vgic_dist *dist = &kvm->arch.vgic;
        struct vgic_translation_cache_entry *cte;
        unsigned long flags;
        phys_addr_t db;

        /* Do not cache a directly injected interrupt */
        if (irq->hw)
                return;

        raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);

        if (unlikely(list_empty(&dist->lpi_translation_cache)))
                goto out;

        /*
         * We could have raced with another CPU caching the same
         * translation behind our back, so let's check it is not in
         * already
         */
        db = its->vgic_its_base + GITS_TRANSLATER;
        if (__vgic_its_check_cache(dist, db, devid, eventid))
                goto out;

        /* Always reuse the last entry (LRU policy) */
        cte = list_last_entry(&dist->lpi_translation_cache,
                              typeof(*cte), entry);

        /*
         * Caching the translation implies having an extra reference
         * to the interrupt, so drop the potential reference on what
         * was in the cache, and increment it on the new interrupt.
         */
        if (cte->irq)
                __vgic_put_lpi_locked(kvm, cte->irq);

        vgic_get_irq_kref(irq);

        cte->db         = db;
        cte->devid      = devid;
        cte->eventid    = eventid;
        cte->irq        = irq;

        /* Move the new translation to the head of the list */
        list_move(&cte->entry, &dist->lpi_translation_cache);

out:
        raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
}

void vgic_its_invalidate_cache(struct kvm *kvm)
{
        struct vgic_dist *dist = &kvm->arch.vgic;
        struct vgic_translation_cache_entry *cte;
        unsigned long flags;

        raw_spin_lock_irqsave(&dist->lpi_list_lock, flags);

        list_for_each_entry(cte, &dist->lpi_translation_cache, entry) {
                /*
                 * If we hit a NULL entry, there is nothing after this
                 * point.
                 */
                if (!cte->irq)
                        break;

                __vgic_put_lpi_locked(kvm, cte->irq);
                cte->irq = NULL;
        }

        raw_spin_unlock_irqrestore(&dist->lpi_list_lock, flags);
}

int vgic_its_resolve_lpi(struct kvm *kvm, struct vgic_its *its,
                         u32 devid, u32 eventid, struct vgic_irq **irq)
{
        struct kvm_vcpu *vcpu;
        struct its_ite *ite;

        if (!its->enabled)
                return -EBUSY;

        ite = find_ite(its, devid, eventid);
        if (!ite || !its_is_collection_mapped(ite->collection))
                return E_ITS_INT_UNMAPPED_INTERRUPT;

        vcpu = kvm_get_vcpu(kvm, ite->collection->target_addr);
        if (!vcpu)
                return E_ITS_INT_UNMAPPED_INTERRUPT;

        if (!vcpu->arch.vgic_cpu.lpis_enabled)
                return -EBUSY;

        vgic_its_cache_translation(kvm, its, devid, eventid, ite->irq);

        *irq = ite->irq;
        return 0;
}

struct vgic_its *vgic_msi_to_its(struct kvm *kvm, struct kvm_msi *msi)
{
        u64 address;
        struct kvm_io_device *kvm_io_dev;
        struct vgic_io_device *iodev;

        if (!vgic_has_its(kvm))
                return ERR_PTR(-ENODEV);

        if (!(msi->flags & KVM_MSI_VALID_DEVID))
                return ERR_PTR(-EINVAL);

        address = (u64)msi->address_hi << 32 | msi->address_lo;

        kvm_io_dev = kvm_io_bus_get_dev(kvm, KVM_MMIO_BUS, address);
        if (!kvm_io_dev)
                return ERR_PTR(-EINVAL);

        if (kvm_io_dev->ops != &kvm_io_gic_ops)
                return ERR_PTR(-EINVAL);

        iodev = container_of(kvm_io_dev, struct vgic_io_device, dev);
        if (iodev->iodev_type != IODEV_ITS)
                return ERR_PTR(-EINVAL);

        return iodev->its;
}

/*
 * Find the target VCPU and the LPI number for a given devid/eventid pair
 * and make this IRQ pending, possibly injecting it.
 * Must be called with the its_lock mutex held.
 * Returns 0 on success, a positive error value for any ITS mapping
 * related errors and negative error values for generic errors.
 */
static int vgic_its_trigger_msi(struct kvm *kvm, struct vgic_its *its,
                                u32 devid, u32 eventid)
{
        struct vgic_irq *irq = NULL;
        unsigned long flags;
        int err;

        err = vgic_its_resolve_lpi(kvm, its, devid, eventid, &irq);
        if (err)
                return err;

        if (irq->hw)
                return irq_set_irqchip_state(irq->host_irq,
                                             IRQCHIP_STATE_PENDING, true);

        raw_spin_lock_irqsave(&irq->irq_lock, flags);
        irq->pending_latch = true;
        vgic_queue_irq_unlock(kvm, irq, flags);

        return 0;
}

int vgic_its_inject_cached_translation(struct kvm *kvm, struct kvm_msi *msi)
{
        struct vgic_irq *irq;
        unsigned long flags;
        phys_addr_t db;

        db = (u64)msi->address_hi << 32 | msi->address_lo;
        irq = vgic_its_check_cache(kvm, db, msi->devid, msi->data);
        if (!irq)
                return -EWOULDBLOCK;

        raw_spin_lock_irqsave(&irq->irq_lock, flags);
        irq->pending_latch = true;
        vgic_queue_irq_unlock(kvm, irq, flags);

        return 0;
}

/*
 * Queries the KVM IO bus framework to get the ITS pointer from the given
 * doorbell address.
 * We then call vgic_its_trigger_msi() with the decoded data.
 * According to the KVM_SIGNAL_MSI API description returns 1 on success.
 */
int vgic_its_inject_msi(struct kvm *kvm, struct kvm_msi *msi)
{
        struct vgic_its *its;
        int ret;

        if (!vgic_its_inject_cached_translation(kvm, msi))
                return 1;

        its = vgic_msi_to_its(kvm, msi);
        if (IS_ERR(its))
                return PTR_ERR(its);

        mutex_lock(&its->its_lock);
        ret = vgic_its_trigger_msi(kvm, its, msi->devid, msi->data);
        mutex_unlock(&its->its_lock);

        if (ret < 0)
                return ret;

        /*
         * KVM_SIGNAL_MSI demands a return value > 0 for success and 0
         * if the guest has blocked the MSI. So we map any LPI mapping
         * related error to that.
         */
        if (ret)
                return 0;
        else
                return 1;
}

/* Requires the its_lock to be held. */
static void its_free_ite(struct kvm *kvm, struct its_ite *ite)
{
        list_del(&ite->ite_list);

        /* This put matches the get in vgic_add_lpi. */
        if (ite->irq) {
                if (ite->irq->hw)
                        WARN_ON(its_unmap_vlpi(ite->irq->host_irq));

                vgic_put_irq(kvm, ite->irq);
        }

        kfree(ite);
}

static u64 its_cmd_mask_field(u64 *its_cmd, int word, int shift, int size)
{
        return (le64_to_cpu(its_cmd[word]) >> shift) & (BIT_ULL(size) - 1);
}

#define its_cmd_get_command(cmd)        its_cmd_mask_field(cmd, 0,  0,  8)
#define its_cmd_get_deviceid(cmd)       its_cmd_mask_field(cmd, 0, 32, 32)
#define its_cmd_get_size(cmd)           (its_cmd_mask_field(cmd, 1,  0,  5) + 1)
#define its_cmd_get_id(cmd)             its_cmd_mask_field(cmd, 1,  0, 32)
#define its_cmd_get_physical_id(cmd)    its_cmd_mask_field(cmd, 1, 32, 32)
#define its_cmd_get_collection(cmd)     its_cmd_mask_field(cmd, 2,  0, 16)
#define its_cmd_get_ittaddr(cmd)        (its_cmd_mask_field(cmd, 2,  8, 44) << 8)
#define its_cmd_get_target_addr(cmd)    its_cmd_mask_field(cmd, 2, 16, 32)
#define its_cmd_get_validbit(cmd)       its_cmd_mask_field(cmd, 2, 63,  1)

/*
 * The DISCARD command frees an Interrupt Translation Table Entry (ITTE).
 * Must be called with the its_lock mutex held.
 */
static int vgic_its_cmd_handle_discard(struct kvm *kvm, struct vgic_its *its,
                                       u64 *its_cmd)
{
        u32 device_id = its_cmd_get_deviceid(its_cmd);
        u32 event_id = its_cmd_get_id(its_cmd);
        struct its_ite *ite;

        ite = find_ite(its, device_id, event_id);
        if (ite && its_is_collection_mapped(ite->collection)) {
                /*
                 * Though the spec talks about removing the pending state, we
                 * don't bother here since we clear the ITTE anyway and the
                 * pending state is a property of the ITTE struct.
                 */
                vgic_its_invalidate_cache(kvm);

                its_free_ite(kvm, ite);
                return 0;
        }

        return E_ITS_DISCARD_UNMAPPED_INTERRUPT;
}

/*
 * The MOVI command moves an ITTE to a different collection.
 * Must be called with the its_lock mutex held.
 */
static int vgic_its_cmd_handle_movi(struct kvm *kvm, struct vgic_its *its,
                                    u64 *its_cmd)
{
        u32 device_id = its_cmd_get_deviceid(its_cmd);
        u32 event_id = its_cmd_get_id(its_cmd);
        u32 coll_id = its_cmd_get_collection(its_cmd);
        struct kvm_vcpu *vcpu;
        struct its_ite *ite;
        struct its_collection *collection;

        ite = find_ite(its, device_id, event_id);
        if (!ite)
                return E_ITS_MOVI_UNMAPPED_INTERRUPT;

        if (!its_is_collection_mapped(ite->collection))
                return E_ITS_MOVI_UNMAPPED_COLLECTION;

        collection = find_collection(its, coll_id);
        if (!its_is_collection_mapped(collection))
                return E_ITS_MOVI_UNMAPPED_COLLECTION;

        ite->collection = collection;
        vcpu = kvm_get_vcpu(kvm, collection->target_addr);

        vgic_its_invalidate_cache(kvm);

        return update_affinity(ite->irq, vcpu);
}

/*
 * Check whether an ID can be stored into the corresponding guest table.
 * For a direct table this is pretty easy, but gets a bit nasty for
 * indirect tables. We check whether the resulting guest physical address
 * is actually valid (covered by a memslot and guest accessible).
 * For this we have to read the respective first level entry.
 */
static bool vgic_its_check_id(struct vgic_its *its, u64 baser, u32 id,
                              gpa_t *eaddr)
{
        int l1_tbl_size = GITS_BASER_NR_PAGES(baser) * SZ_64K;
        u64 indirect_ptr, type = GITS_BASER_TYPE(baser);
        phys_addr_t base = GITS_BASER_ADDR_48_to_52(baser);
        int esz = GITS_BASER_ENTRY_SIZE(baser);
        int index, idx;
        gfn_t gfn;
        bool ret;

        switch (type) {
        case GITS_BASER_TYPE_DEVICE:
                if (id >= BIT_ULL(VITS_TYPER_DEVBITS))
                        return false;
                break;
        case GITS_BASER_TYPE_COLLECTION:
                /* as GITS_TYPER.CIL == 0, ITS supports 16-bit collection ID */
                if (id >= BIT_ULL(16))
                        return false;
                break;
        default:
                return false;
        }

        if (!(baser & GITS_BASER_INDIRECT)) {
                phys_addr_t addr;

                if (id >= (l1_tbl_size / esz))
                        return false;

                addr = base + id * esz;
                gfn = addr >> PAGE_SHIFT;

                if (eaddr)
                        *eaddr = addr;

                goto out;
        }

        /* calculate and check the index into the 1st level */
        index = id / (SZ_64K / esz);
        if (index >= (l1_tbl_size / sizeof(u64)))
                return false;

        /* Each 1st level entry is represented by a 64-bit value. */
        if (kvm_read_guest_lock(its->dev->kvm,
                           base + index * sizeof(indirect_ptr),
                           &indirect_ptr, sizeof(indirect_ptr)))
                return false;

        indirect_ptr = le64_to_cpu(indirect_ptr);

        /* check the valid bit of the first level entry */
        if (!(indirect_ptr & BIT_ULL(63)))
                return false;

        /* Mask the guest physical address and calculate the frame number. */
        indirect_ptr &= GENMASK_ULL(51, 16);

        /* Find the address of the actual entry */
        index = id % (SZ_64K / esz);
        indirect_ptr += index * esz;
        gfn = indirect_ptr >> PAGE_SHIFT;

        if (eaddr)
                *eaddr = indirect_ptr;

out:
        idx = srcu_read_lock(&its->dev->kvm->srcu);
        ret = kvm_is_visible_gfn(its->dev->kvm, gfn);
        srcu_read_unlock(&its->dev->kvm->srcu, idx);
        return ret;
}

static int vgic_its_alloc_collection(struct vgic_its *its,
                                     struct its_collection **colp,
                                     u32 coll_id)
{
        struct its_collection *collection;

        if (!vgic_its_check_id(its, its->baser_coll_table, coll_id, NULL))
                return E_ITS_MAPC_COLLECTION_OOR;

        collection = kzalloc(sizeof(*collection), GFP_KERNEL);
        if (!collection)
                return -ENOMEM;

        collection->collection_id = coll_id;
        collection->target_addr = COLLECTION_NOT_MAPPED;

        list_add_tail(&collection->coll_list, &its->collection_list);
        *colp = collection;

        return 0;
}

static void vgic_its_free_collection(struct vgic_its *its, u32 coll_id)
{
        struct its_collection *collection;
        struct its_device *device;
        struct its_ite *ite;

        /*
         * Clearing the mapping for that collection ID removes the
         * entry from the list. If there wasn't any before, we can
         * go home early.
         */
        collection = find_collection(its, coll_id);
        if (!collection)
                return;

        for_each_lpi_its(device, ite, its)
                if (ite->collection &&
                    ite->collection->collection_id == coll_id)
                        ite->collection = NULL;

        list_del(&collection->coll_list);
        kfree(collection);
}

/* Must be called with its_lock mutex held */
static struct its_ite *vgic_its_alloc_ite(struct its_device *device,
                                          struct its_collection *collection,
                                          u32 event_id)
{
        struct its_ite *ite;

        ite = kzalloc(sizeof(*ite), GFP_KERNEL);
        if (!ite)
                return ERR_PTR(-ENOMEM);

        ite->event_id   = event_id;
        ite->collection = collection;

        list_add_tail(&ite->ite_list, &device->itt_head);
        return ite;
}

/*
 * The MAPTI and MAPI commands map LPIs to ITTEs.
 * Must be called with its_lock mutex held.
 */
static int vgic_its_cmd_handle_mapi(struct kvm *kvm, struct vgic_its *its,
                                    u64 *its_cmd)
{
        u32 device_id = its_cmd_get_deviceid(its_cmd);
        u32 event_id = its_cmd_get_id(its_cmd);
        u32 coll_id = its_cmd_get_collection(its_cmd);
        struct its_ite *ite;
        struct kvm_vcpu *vcpu = NULL;
        struct its_device *device;
        struct its_collection *collection, *new_coll = NULL;
        struct vgic_irq *irq;
        int lpi_nr;

        device = find_its_device(its, device_id);
        if (!device)
                return E_ITS_MAPTI_UNMAPPED_DEVICE;

        if (event_id >= BIT_ULL(device->num_eventid_bits))
                return E_ITS_MAPTI_ID_OOR;

        if (its_cmd_get_command(its_cmd) == GITS_CMD_MAPTI)
                lpi_nr = its_cmd_get_physical_id(its_cmd);
        else
                lpi_nr = event_id;
        if (lpi_nr < GIC_LPI_OFFSET ||
            lpi_nr >= max_lpis_propbaser(kvm->arch.vgic.propbaser))
                return E_ITS_MAPTI_PHYSICALID_OOR;

        /* If there is an existing mapping, behavior is UNPREDICTABLE. */
        if (find_ite(its, device_id, event_id))
                return 0;

        collection = find_collection(its, coll_id);
        if (!collection) {
                int ret = vgic_its_alloc_collection(its, &collection, coll_id);
                if (ret)
                        return ret;
                new_coll = collection;
        }

        ite = vgic_its_alloc_ite(device, collection, event_id);
        if (IS_ERR(ite)) {
                if (new_coll)
                        vgic_its_free_collection(its, coll_id);
                return PTR_ERR(ite);
        }

        if (its_is_collection_mapped(collection))
                vcpu = kvm_get_vcpu(kvm, collection->target_addr);

        irq = vgic_add_lpi(kvm, lpi_nr, vcpu);
        if (IS_ERR(irq)) {
                if (new_coll)
                        vgic_its_free_collection(its, coll_id);
                its_free_ite(kvm, ite);
                return PTR_ERR(irq);
        }
        ite->irq = irq;

        return 0;
}

/* Requires the its_lock to be held. */
static void vgic_its_free_device(struct kvm *kvm, struct its_device *device)
{
        struct its_ite *ite, *temp;

        /*
         * The spec says that unmapping a device with still valid
         * ITTEs associated is UNPREDICTABLE. We remove all ITTEs,
         * since we cannot leave the memory unreferenced.
         */
        list_for_each_entry_safe(ite, temp, &device->itt_head, ite_list)
                its_free_ite(kvm, ite);

        vgic_its_invalidate_cache(kvm);

        list_del(&device->dev_list);
        kfree(device);
}

/* its lock must be held */
static void vgic_its_free_device_list(struct kvm *kvm, struct vgic_its *its)
{
        struct its_device *cur, *temp;

        list_for_each_entry_safe(cur, temp, &its->device_list, dev_list)
                vgic_its_free_device(kvm, cur);
}

/* its lock must be held */
static void vgic_its_free_collection_list(struct kvm *kvm, struct vgic_its *its)
{
        struct its_collection *cur, *temp;

        list_for_each_entry_safe(cur, temp, &its->collection_list, coll_list)
                vgic_its_free_collection(its, cur->collection_id);
}

/* Must be called with its_lock mutex held */
static struct its_device *vgic_its_alloc_device(struct vgic_its *its,
                                                u32 device_id, gpa_t itt_addr,
                                                u8 num_eventid_bits)
{
        struct its_device *device;

        device = kzalloc(sizeof(*device), GFP_KERNEL);
        if (!device)
                return ERR_PTR(-ENOMEM);

        device->device_id = device_id;
        device->itt_addr = itt_addr;
        device->num_eventid_bits = num_eventid_bits;
        INIT_LIST_HEAD(&device->itt_head);

        list_add_tail(&device->dev_list, &its->device_list);
        return device;
}

/*
 * MAPD maps or unmaps a device ID to Interrupt Translation Tables (ITTs).
 * Must be called with the its_lock mutex held.
 */
static int vgic_its_cmd_handle_mapd(struct kvm *kvm, struct vgic_its *its,
                                    u64 *its_cmd)
{
        u32 device_id = its_cmd_get_deviceid(its_cmd);
        bool valid = its_cmd_get_validbit(its_cmd);
        u8 num_eventid_bits = its_cmd_get_size(its_cmd);
        gpa_t itt_addr = its_cmd_get_ittaddr(its_cmd);
        struct its_device *device;

        if (!vgic_its_check_id(its, its->baser_device_table, device_id, NULL))
                return E_ITS_MAPD_DEVICE_OOR;

        if (valid && num_eventid_bits > VITS_TYPER_IDBITS)
                return E_ITS_MAPD_ITTSIZE_OOR;

        device = find_its_device(its, device_id);

        /*
         * The spec says that calling MAPD on an already mapped device
         * invalidates all cached data for this device. We implement this
         * by removing the mapping and re-establishing it.
         */
        if (device)
                vgic_its_free_device(kvm, device);

        /*
         * The spec does not say whether unmapping a not-mapped device
         * is an error, so we are done in any case.
         */
        if (!valid)
                return 0;

        device = vgic_its_alloc_device(its, device_id, itt_addr,
                                       num_eventid_bits);

        return PTR_ERR_OR_ZERO(device);
}

/*
 * The MAPC command maps collection IDs to redistributors.
 * Must be called with the its_lock mutex held.
 */
static int vgic_its_cmd_handle_mapc(struct kvm *kvm, struct vgic_its *its,
                                    u64 *its_cmd)
{
        u16 coll_id;
        u32 target_addr;
        struct its_collection *collection;
        bool valid;

        valid = its_cmd_get_validbit(its_cmd);
        coll_id = its_cmd_get_collection(its_cmd);
        target_addr = its_cmd_get_target_addr(its_cmd);

        if (target_addr >= atomic_read(&kvm->online_vcpus))
                return E_ITS_MAPC_PROCNUM_OOR;

        if (!valid) {
                vgic_its_free_collection(its, coll_id);
                vgic_its_invalidate_cache(kvm);
        } else {
                collection = find_collection(its, coll_id);

                if (!collection) {
                        int ret;

                        ret = vgic_its_alloc_collection(its, &collection,
                                                        coll_id);
                        if (ret)
                                return ret;
                        collection->target_addr = target_addr;
                } else {
                        collection->target_addr = target_addr;
                        update_affinity_collection(kvm, its, collection);
                }
        }

        return 0;
}

/*
 * The CLEAR command removes the pending state for a particular LPI.
 * Must be called with the its_lock mutex held.
 */
static int vgic_its_cmd_handle_clear(struct kvm *kvm, struct vgic_its *its,
                                     u64 *its_cmd)
{
        u32 device_id = its_cmd_get_deviceid(its_cmd);
        u32 event_id = its_cmd_get_id(its_cmd);
        struct its_ite *ite;


        ite = find_ite(its, device_id, event_id);
        if (!ite)
                return E_ITS_CLEAR_UNMAPPED_INTERRUPT;

        ite->irq->pending_latch = false;

        if (ite->irq->hw)
                return irq_set_irqchip_state(ite->irq->host_irq,
                                             IRQCHIP_STATE_PENDING, false);

        return 0;
}

/*
 * The INV command syncs the configuration bits from the memory table.
 * Must be called with the its_lock mutex held.
 */
static int vgic_its_cmd_handle_inv(struct kvm *kvm, struct vgic_its *its,
                                   u64 *its_cmd)
{
        u32 device_id = its_cmd_get_deviceid(its_cmd);
        u32 event_id = its_cmd_get_id(its_cmd);
        struct its_ite *ite;


        ite = find_ite(its, device_id, event_id);
        if (!ite)
                return E_ITS_INV_UNMAPPED_INTERRUPT;

        return update_lpi_config(kvm, ite->irq, NULL, true);
}

/*
 * The INVALL command requests flushing of all IRQ data in this collection.
 * Find the VCPU mapped to that collection, then iterate over the VM's list
 * of mapped LPIs and update the configuration for each IRQ which targets
 * the specified vcpu. The configuration will be read from the in-memory
 * configuration table.
 * Must be called with the its_lock mutex held.
 */
static int vgic_its_cmd_handle_invall(struct kvm *kvm, struct vgic_its *its,
                                      u64 *its_cmd)
{
        u32 coll_id = its_cmd_get_collection(its_cmd);
        struct its_collection *collection;
        struct kvm_vcpu *vcpu;
        struct vgic_irq *irq;
        u32 *intids;
        int irq_count, i;

        collection = find_collection(its, coll_id);
        if (!its_is_collection_mapped(collection))
                return E_ITS_INVALL_UNMAPPED_COLLECTION;

        vcpu = kvm_get_vcpu(kvm, collection->target_addr);

        irq_count = vgic_copy_lpi_list(kvm, vcpu, &intids);
        if (irq_count < 0)
                return irq_count;

        for (i = 0; i < irq_count; i++) {
                irq = vgic_get_irq(kvm, NULL, intids[i]);
                if (!irq)
                        continue;
                update_lpi_config(kvm, irq, vcpu, false);
                vgic_put_irq(kvm, irq);
        }

        kfree(intids);

        if (vcpu->arch.vgic_cpu.vgic_v3.its_vpe.its_vm)
                its_invall_vpe(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe);

        return 0;
}

/*
 * The MOVALL command moves the pending state of all IRQs targeting one
 * redistributor to another. We don't hold the pending state in the VCPUs,
 * but in the IRQs instead, so there is really not much to do for us here.
 * However the spec says that no IRQ must target the old redistributor
 * afterwards, so we make sure that no LPI is using the associated target_vcpu.
 * This command affects all LPIs in the system that target that redistributor.
 */
static int vgic_its_cmd_handle_movall(struct kvm *kvm, struct vgic_its *its,
                                      u64 *its_cmd)
{
        u32 target1_addr = its_cmd_get_target_addr(its_cmd);
        u32 target2_addr = its_cmd_mask_field(its_cmd, 3, 16, 32);
        struct kvm_vcpu *vcpu1, *vcpu2;
        struct vgic_irq *irq;
        u32 *intids;
        int irq_count, i;

        if (target1_addr >= atomic_read(&kvm->online_vcpus) ||
            target2_addr >= atomic_read(&kvm->online_vcpus))
                return E_ITS_MOVALL_PROCNUM_OOR;

        if (target1_addr == target2_addr)
                return 0;

        vcpu1 = kvm_get_vcpu(kvm, target1_addr);
        vcpu2 = kvm_get_vcpu(kvm, target2_addr);

        irq_count = vgic_copy_lpi_list(kvm, vcpu1, &intids);
        if (irq_count < 0)
                return irq_count;

        for (i = 0; i < irq_count; i++) {
                irq = vgic_get_irq(kvm, NULL, intids[i]);

                update_affinity(irq, vcpu2);

                vgic_put_irq(kvm, irq);
        }

        vgic_its_invalidate_cache(kvm);

        kfree(intids);
        return 0;
}

/*
 * The INT command injects the LPI associated with that DevID/EvID pair.
 * Must be called with the its_lock mutex held.
 */
static int vgic_its_cmd_handle_int(struct kvm *kvm, struct vgic_its *its,
                                   u64 *its_cmd)
{
        u32 msi_data = its_cmd_get_id(its_cmd);
        u64 msi_devid = its_cmd_get_deviceid(its_cmd);

        return vgic_its_trigger_msi(kvm, its, msi_devid, msi_data);
}

/*
 * This function is called with the its_cmd lock held, but the ITS data
 * structure lock dropped.
 */
static int vgic_its_handle_command(struct kvm *kvm, struct vgic_its *its,
                                   u64 *its_cmd)
{
        int ret = -ENODEV;

        mutex_lock(&its->its_lock);
        switch (its_cmd_get_command(its_cmd)) {
        case GITS_CMD_MAPD:
                ret = vgic_its_cmd_handle_mapd(kvm, its, its_cmd);
                break;
        case GITS_CMD_MAPC:
                ret = vgic_its_cmd_handle_mapc(kvm, its, its_cmd);
                break;
        case GITS_CMD_MAPI:
                ret = vgic_its_cmd_handle_mapi(kvm, its, its_cmd);
                break;
        case GITS_CMD_MAPTI:
                ret = vgic_its_cmd_handle_mapi(kvm, its, its_cmd);
                break;
        case GITS_CMD_MOVI:
                ret = vgic_its_cmd_handle_movi(kvm, its, its_cmd);
                break;
        case GITS_CMD_DISCARD:
                ret = vgic_its_cmd_handle_discard(kvm, its, its_cmd);
                break;
        case GITS_CMD_CLEAR:
                ret = vgic_its_cmd_handle_clear(kvm, its, its_cmd);
                break;
        case GITS_CMD_MOVALL:
                ret = vgic_its_cmd_handle_movall(kvm, its, its_cmd);
                break;
        case GITS_CMD_INT:
                ret = vgic_its_cmd_handle_int(kvm, its, its_cmd);
                break;
        case GITS_CMD_INV:
                ret = vgic_its_cmd_handle_inv(kvm, its, its_cmd);
                break;
        case GITS_CMD_INVALL:
                ret = vgic_its_cmd_handle_invall(kvm, its, its_cmd);
                break;
        case GITS_CMD_SYNC:
                /* we ignore this command: we are in sync all of the time */
                ret = 0;
                break;
        }
        mutex_unlock(&its->its_lock);

        return ret;
}

static u64 vgic_sanitise_its_baser(u64 reg)
{
        reg = vgic_sanitise_field(reg, GITS_BASER_SHAREABILITY_MASK,
                                  GITS_BASER_SHAREABILITY_SHIFT,
                                  vgic_sanitise_shareability);
        reg = vgic_sanitise_field(reg, GITS_BASER_INNER_CACHEABILITY_MASK,
                                  GITS_BASER_INNER_CACHEABILITY_SHIFT,
                                  vgic_sanitise_inner_cacheability);
        reg = vgic_sanitise_field(reg, GITS_BASER_OUTER_CACHEABILITY_MASK,
                                  GITS_BASER_OUTER_CACHEABILITY_SHIFT,
                                  vgic_sanitise_outer_cacheability);

        /* We support only one (ITS) page size: 64K */
        reg = (reg & ~GITS_BASER_PAGE_SIZE_MASK) | GITS_BASER_PAGE_SIZE_64K;

        return reg;
}

static u64 vgic_sanitise_its_cbaser(u64 reg)
{
        reg = vgic_sanitise_field(reg, GITS_CBASER_SHAREABILITY_MASK,
                                  GITS_CBASER_SHAREABILITY_SHIFT,
                                  vgic_sanitise_shareability);
        reg = vgic_sanitise_field(reg, GITS_CBASER_INNER_CACHEABILITY_MASK,
                                  GITS_CBASER_INNER_CACHEABILITY_SHIFT,
                                  vgic_sanitise_inner_cacheability);
        reg = vgic_sanitise_field(reg, GITS_CBASER_OUTER_CACHEABILITY_MASK,
                                  GITS_CBASER_OUTER_CACHEABILITY_SHIFT,
                                  vgic_sanitise_outer_cacheability);

        /* Sanitise the physical address to be 64k aligned. */
        reg &= ~GENMASK_ULL(15, 12);

        return reg;
}

static unsigned long vgic_mmio_read_its_cbaser(struct kvm *kvm,
                                               struct vgic_its *its,
                                               gpa_t addr, unsigned int len)
{
        return extract_bytes(its->cbaser, addr & 7, len);
}

static void vgic_mmio_write_its_cbaser(struct kvm *kvm, struct vgic_its *its,
                                       gpa_t addr, unsigned int len,
                                       unsigned long val)
{
        /* When GITS_CTLR.Enable is 1, this register is RO. */
        if (its->enabled)
                return;

        mutex_lock(&its->cmd_lock);
        its->cbaser = update_64bit_reg(its->cbaser, addr & 7, len, val);
        its->cbaser = vgic_sanitise_its_cbaser(its->cbaser);
        its->creadr = 0;
        /*
         * CWRITER is architecturally UNKNOWN on reset, but we need to reset
         * it to CREADR to make sure we start with an empty command buffer.
         */
        its->cwriter = its->creadr;
        mutex_unlock(&its->cmd_lock);
}

#define ITS_CMD_BUFFER_SIZE(baser)      ((((baser) & 0xff) + 1) << 12)
#define ITS_CMD_SIZE                    32
#define ITS_CMD_OFFSET(reg)             ((reg) & GENMASK(19, 5))

/* Must be called with the cmd_lock held. */
static void vgic_its_process_commands(struct kvm *kvm, struct vgic_its *its)
{
        gpa_t cbaser;
        u64 cmd_buf[4];

        /* Commands are only processed when the ITS is enabled. */
        if (!its->enabled)
                return;

        cbaser = GITS_CBASER_ADDRESS(its->cbaser);

        while (its->cwriter != its->creadr) {
                int ret = kvm_read_guest_lock(kvm, cbaser + its->creadr,
                                              cmd_buf, ITS_CMD_SIZE);
                /*
                 * If kvm_read_guest() fails, this could be due to the guest
                 * programming a bogus value in CBASER or something else going
                 * wrong from which we cannot easily recover.
                 * According to section 6.3.2 in the GICv3 spec we can just
                 * ignore that command then.
                 */
                if (!ret)
                        vgic_its_handle_command(kvm, its, cmd_buf);

                its->creadr += ITS_CMD_SIZE;
                if (its->creadr == ITS_CMD_BUFFER_SIZE(its->cbaser))
                        its->creadr = 0;
        }
}

/*
 * By writing to CWRITER the guest announces new commands to be processed.
 * To avoid any races in the first place, we take the its_cmd lock, which
 * protects our ring buffer variables, so that there is only one user
 * per ITS handling commands at a given time.
 */
static void vgic_mmio_write_its_cwriter(struct kvm *kvm, struct vgic_its *its,
                                        gpa_t addr, unsigned int len,
                                        unsigned long val)
{
        u64 reg;

        if (!its)
                return;

        mutex_lock(&its->cmd_lock);

        reg = update_64bit_reg(its->cwriter, addr & 7, len, val);
        reg = ITS_CMD_OFFSET(reg);
        if (reg >= ITS_CMD_BUFFER_SIZE(its->cbaser)) {
                mutex_unlock(&its->cmd_lock);
                return;
        }
        its->cwriter = reg;

        vgic_its_process_commands(kvm, its);

        mutex_unlock(&its->cmd_lock);
}

static unsigned long vgic_mmio_read_its_cwriter(struct kvm *kvm,
                                                struct vgic_its *its,
                                                gpa_t addr, unsigned int len)
{
        return extract_bytes(its->cwriter, addr & 0x7, len);
}

static unsigned long vgic_mmio_read_its_creadr(struct kvm *kvm,
                                               struct vgic_its *its,
                                               gpa_t addr, unsigned int len)
{
        return extract_bytes(its->creadr, addr & 0x7, len);
}

static int vgic_mmio_uaccess_write_its_creadr(struct kvm *kvm,
                                              struct vgic_its *its,
                                              gpa_t addr, unsigned int len,
                                              unsigned long val)
{
        u32 cmd_offset;
        int ret = 0;

        mutex_lock(&its->cmd_lock);

        if (its->enabled) {
                ret = -EBUSY;
                goto out;
        }

        cmd_offset = ITS_CMD_OFFSET(val);
        if (cmd_offset >= ITS_CMD_BUFFER_SIZE(its->cbaser)) {
                ret = -EINVAL;
                goto out;
        }

        its->creadr = cmd_offset;
out:
        mutex_unlock(&its->cmd_lock);
        return ret;
}

#define BASER_INDEX(addr) (((addr) / sizeof(u64)) & 0x7)
static unsigned long vgic_mmio_read_its_baser(struct kvm *kvm,
                                              struct vgic_its *its,
                                              gpa_t addr, unsigned int len)
{
        u64 reg;

        switch (BASER_INDEX(addr)) {
        case 0:
                reg = its->baser_device_table;
                break;
        case 1:
                reg = its->baser_coll_table;
                break;
        default:
                reg = 0;
                break;
        }

        return extract_bytes(reg, addr & 7, len);
}

#define GITS_BASER_RO_MASK      (GENMASK_ULL(52, 48) | GENMASK_ULL(58, 56))
static void vgic_mmio_write_its_baser(struct kvm *kvm,
                                      struct vgic_its *its,
                                      gpa_t addr, unsigned int len,
                                      unsigned long val)
{
        const struct vgic_its_abi *abi = vgic_its_get_abi(its);
        u64 entry_size, table_type;
        u64 reg, *regptr, clearbits = 0;

        /* When GITS_CTLR.Enable is 1, we ignore write accesses. */
        if (its->enabled)
                return;

        switch (BASER_INDEX(addr)) {
        case 0:
                regptr = &its->baser_device_table;
                entry_size = abi->dte_esz;
                table_type = GITS_BASER_TYPE_DEVICE;
                break;
        case 1:
                regptr = &its->baser_coll_table;
                entry_size = abi->cte_esz;
                table_type = GITS_BASER_TYPE_COLLECTION;
                clearbits = GITS_BASER_INDIRECT;
                break;
        default:
                return;
        }

        reg = update_64bit_reg(*regptr, addr & 7, len, val);
        reg &= ~GITS_BASER_RO_MASK;
        reg &= ~clearbits;

        reg |= (entry_size - 1) << GITS_BASER_ENTRY_SIZE_SHIFT;
        reg |= table_type << GITS_BASER_TYPE_SHIFT;
        reg = vgic_sanitise_its_baser(reg);

        *regptr = reg;

        if (!(reg & GITS_BASER_VALID)) {
                /* Take the its_lock to prevent a race with a save/restore */
                mutex_lock(&its->its_lock);
                switch (table_type) {
                case GITS_BASER_TYPE_DEVICE:
                        vgic_its_free_device_list(kvm, its);
                        break;
                case GITS_BASER_TYPE_COLLECTION:
                        vgic_its_free_collection_list(kvm, its);
                        break;
                }
                mutex_unlock(&its->its_lock);
        }
}

static unsigned long vgic_mmio_read_its_ctlr(struct kvm *vcpu,
                                             struct vgic_its *its,
                                             gpa_t addr, unsigned int len)
{
        u32 reg = 0;

        mutex_lock(&its->cmd_lock);
        if (its->creadr == its->cwriter)
                reg |= GITS_CTLR_QUIESCENT;
        if (its->enabled)
                reg |= GITS_CTLR_ENABLE;
        mutex_unlock(&its->cmd_lock);

        return reg;
}

static void vgic_mmio_write_its_ctlr(struct kvm *kvm, struct vgic_its *its,
                                     gpa_t addr, unsigned int len,
                                     unsigned long val)
{
        mutex_lock(&its->cmd_lock);

        /*
         * It is UNPREDICTABLE to enable the ITS if any of the CBASER or
         * device/collection BASER are invalid
         */
        if (!its->enabled && (val & GITS_CTLR_ENABLE) &&
                (!(its->baser_device_table & GITS_BASER_VALID) ||
                 !(its->baser_coll_table & GITS_BASER_VALID) ||
                 !(its->cbaser & GITS_CBASER_VALID)))
                goto out;

        its->enabled = !!(val & GITS_CTLR_ENABLE);
        if (!its->enabled)
                vgic_its_invalidate_cache(kvm);

        /*
         * Try to process any pending commands. This function bails out early
         * if the ITS is disabled or no commands have been queued.
         */
        vgic_its_process_commands(kvm, its);

out:
        mutex_unlock(&its->cmd_lock);
}

#define REGISTER_ITS_DESC(off, rd, wr, length, acc)             \
{                                                               \
        .reg_offset = off,                                      \
        .len = length,                                          \
        .access_flags = acc,                                    \
        .its_read = rd,                                         \
        .its_write = wr,                                        \
}

#define REGISTER_ITS_DESC_UACCESS(off, rd, wr, uwr, length, acc)\
{                                                               \
        .reg_offset = off,                                      \
        .len = length,                                          \
        .access_flags = acc,                                    \
        .its_read = rd,                                         \
        .its_write = wr,                                        \
        .uaccess_its_write = uwr,                               \
}

static void its_mmio_write_wi(struct kvm *kvm, struct vgic_its *its,
                              gpa_t addr, unsigned int len, unsigned long val)
{
        /* Ignore */
}

static struct vgic_register_region its_registers[] = {
        REGISTER_ITS_DESC(GITS_CTLR,
                vgic_mmio_read_its_ctlr, vgic_mmio_write_its_ctlr, 4,
                VGIC_ACCESS_32bit),
        REGISTER_ITS_DESC_UACCESS(GITS_IIDR,
                vgic_mmio_read_its_iidr, its_mmio_write_wi,
                vgic_mmio_uaccess_write_its_iidr, 4,
                VGIC_ACCESS_32bit),
        REGISTER_ITS_DESC(GITS_TYPER,
                vgic_mmio_read_its_typer, its_mmio_write_wi, 8,
                VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
        REGISTER_ITS_DESC(GITS_CBASER,
                vgic_mmio_read_its_cbaser, vgic_mmio_write_its_cbaser, 8,
                VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
        REGISTER_ITS_DESC(GITS_CWRITER,
                vgic_mmio_read_its_cwriter, vgic_mmio_write_its_cwriter, 8,
                VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
        REGISTER_ITS_DESC_UACCESS(GITS_CREADR,
                vgic_mmio_read_its_creadr, its_mmio_write_wi,
                vgic_mmio_uaccess_write_its_creadr, 8,
                VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
        REGISTER_ITS_DESC(GITS_BASER,
                vgic_mmio_read_its_baser, vgic_mmio_write_its_baser, 0x40,
                VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
        REGISTER_ITS_DESC(GITS_IDREGS_BASE,
                vgic_mmio_read_its_idregs, its_mmio_write_wi, 0x30,
                VGIC_ACCESS_32bit),
};

/* This is called on setting the LPI enable bit in the redistributor. */
void vgic_enable_lpis(struct kvm_vcpu *vcpu)
{
        if (!(vcpu->arch.vgic_cpu.pendbaser & GICR_PENDBASER_PTZ))
                its_sync_lpi_pending_table(vcpu);
}

static int vgic_register_its_iodev(struct kvm *kvm, struct vgic_its *its,
                                   u64 addr)
{
        struct vgic_io_device *iodev = &its->iodev;
        int ret;

        mutex_lock(&kvm->slots_lock);
        if (!IS_VGIC_ADDR_UNDEF(its->vgic_its_base)) {
                ret = -EBUSY;
                goto out;
        }

        its->vgic_its_base = addr;
        iodev->regions = its_registers;
        iodev->nr_regions = ARRAY_SIZE(its_registers);
        kvm_iodevice_init(&iodev->dev, &kvm_io_gic_ops);

        iodev->base_addr = its->vgic_its_base;
        iodev->iodev_type = IODEV_ITS;
        iodev->its = its;
        ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, iodev->base_addr,
                                      KVM_VGIC_V3_ITS_SIZE, &iodev->dev);
out:
        mutex_unlock(&kvm->slots_lock);

        return ret;
}

/* Default is 16 cached LPIs per vcpu */
#define LPI_DEFAULT_PCPU_CACHE_SIZE     16

void vgic_lpi_translation_cache_init(struct kvm *kvm)
{
        struct vgic_dist *dist = &kvm->arch.vgic;
        unsigned int sz;
        int i;

        if (!list_empty(&dist->lpi_translation_cache))
                return;

        sz = atomic_read(&kvm->online_vcpus) * LPI_DEFAULT_PCPU_CACHE_SIZE;

        for (i = 0; i < sz; i++) {
                struct vgic_translation_cache_entry *cte;

                /* An allocation failure is not fatal */
                cte = kzalloc(sizeof(*cte), GFP_KERNEL);
                if (WARN_ON(!cte))
                        break;

                INIT_LIST_HEAD(&cte->entry);
                list_add(&cte->entry, &dist->lpi_translation_cache);
        }
}

void vgic_lpi_translation_cache_destroy(struct kvm *kvm)
{
        struct vgic_dist *dist = &kvm->arch.vgic;
        struct vgic_translation_cache_entry *cte, *tmp;

        vgic_its_invalidate_cache(kvm);

        list_for_each_entry_safe(cte, tmp,
                                 &dist->lpi_translation_cache, entry) {
                list_del(&cte->entry);
                kfree(cte);
        }
}

#define INITIAL_BASER_VALUE                                               \
        (GIC_BASER_CACHEABILITY(GITS_BASER, INNER, RaWb)                | \
         GIC_BASER_CACHEABILITY(GITS_BASER, OUTER, SameAsInner)         | \
         GIC_BASER_SHAREABILITY(GITS_BASER, InnerShareable)             | \
         GITS_BASER_PAGE_SIZE_64K)

#define INITIAL_PROPBASER_VALUE                                           \
        (GIC_BASER_CACHEABILITY(GICR_PROPBASER, INNER, RaWb)            | \
         GIC_BASER_CACHEABILITY(GICR_PROPBASER, OUTER, SameAsInner)     | \
         GIC_BASER_SHAREABILITY(GICR_PROPBASER, InnerShareable))

static int vgic_its_create(struct kvm_device *dev, u32 type)
{
        struct vgic_its *its;

        if (type != KVM_DEV_TYPE_ARM_VGIC_ITS)
                return -ENODEV;

        its = kzalloc(sizeof(struct vgic_its), GFP_KERNEL);
        if (!its)
                return -ENOMEM;

        if (vgic_initialized(dev->kvm)) {
                int ret = vgic_v4_init(dev->kvm);
                if (ret < 0) {
                        kfree(its);
                        return ret;
                }

                vgic_lpi_translation_cache_init(dev->kvm);
        }

        mutex_init(&its->its_lock);
        mutex_init(&its->cmd_lock);

        its->vgic_its_base = VGIC_ADDR_UNDEF;

        INIT_LIST_HEAD(&its->device_list);
        INIT_LIST_HEAD(&its->collection_list);

        dev->kvm->arch.vgic.msis_require_devid = true;
        dev->kvm->arch.vgic.has_its = true;
        its->enabled = false;
        its->dev = dev;

        its->baser_device_table = INITIAL_BASER_VALUE                   |
                ((u64)GITS_BASER_TYPE_DEVICE << GITS_BASER_TYPE_SHIFT);
        its->baser_coll_table = INITIAL_BASER_VALUE |
                ((u64)GITS_BASER_TYPE_COLLECTION << GITS_BASER_TYPE_SHIFT);
        dev->kvm->arch.vgic.propbaser = INITIAL_PROPBASER_VALUE;

        dev->private = its;

        return vgic_its_set_abi(its, NR_ITS_ABIS - 1);
}

static void vgic_its_destroy(struct kvm_device *kvm_dev)
{
        struct kvm *kvm = kvm_dev->kvm;
        struct vgic_its *its = kvm_dev->private;

        mutex_lock(&its->its_lock);

        vgic_its_free_device_list(kvm, its);
        vgic_its_free_collection_list(kvm, its);

        mutex_unlock(&its->its_lock);
        kfree(its);
        kfree(kvm_dev);/* alloc by kvm_ioctl_create_device, free by .destroy */
}

static int vgic_its_has_attr_regs(struct kvm_device *dev,
                                  struct kvm_device_attr *attr)
{
        const struct vgic_register_region *region;
        gpa_t offset = attr->attr;
        int align;

        align = (offset < GITS_TYPER) || (offset >= GITS_PIDR4) ? 0x3 : 0x7;

        if (offset & align)
                return -EINVAL;

        region = vgic_find_mmio_region(its_registers,
                                       ARRAY_SIZE(its_registers),
                                       offset);
        if (!region)
                return -ENXIO;

        return 0;
}

static int vgic_its_attr_regs_access(struct kvm_device *dev,
                                     struct kvm_device_attr *attr,
                                     u64 *reg, bool is_write)
{
        const struct vgic_register_region *region;
        struct vgic_its *its;
        gpa_t addr, offset;
        unsigned int len;
        int align, ret = 0;

        its = dev->private;
        offset = attr->attr;

        /*
         * Although the spec supports upper/lower 32-bit accesses to
         * 64-bit ITS registers, the userspace ABI requires 64-bit
         * accesses to all 64-bit wide registers. We therefore only
         * support 32-bit accesses to GITS_CTLR, GITS_IIDR and GITS ID
         * registers
         */
        if ((offset < GITS_TYPER) || (offset >= GITS_PIDR4))
                align = 0x3;
        else
                align = 0x7;

        if (offset & align)
                return -EINVAL;

        mutex_lock(&dev->kvm->lock);

        if (IS_VGIC_ADDR_UNDEF(its->vgic_its_base)) {
                ret = -ENXIO;
                goto out;
        }

        region = vgic_find_mmio_region(its_registers,

                                       ARRAY_SIZE(its_registers),
                                       offset);
        if (!region) {
                ret = -ENXIO;
                goto out;
        }

        if (!lock_all_vcpus(dev->kvm)) {
                ret = -EBUSY;
                goto out;
        }

        addr = its->vgic_its_base + offset;

        len = region->access_flags & VGIC_ACCESS_64bit ? 8 : 4;

        if (is_write) {
                if (region->uaccess_its_write)
                        ret = region->uaccess_its_write(dev->kvm, its, addr,
                                                        len, *reg);
                else
                        region->its_write(dev->kvm, its, addr, len, *reg);
        } else {
                *reg = region->its_read(dev->kvm, its, addr, len);
        }
        unlock_all_vcpus(dev->kvm);
out:
        mutex_unlock(&dev->kvm->lock);
        return ret;
}

static u32 compute_next_devid_offset(struct list_head *h,
                                     struct its_device *dev)
{
        struct its_device *next;
        u32 next_offset;

        if (list_is_last(&dev->dev_list, h))
                return 0;
        next = list_next_entry(dev, dev_list);
        next_offset = next->device_id - dev->device_id;

        return min_t(u32, next_offset, VITS_DTE_MAX_DEVID_OFFSET);
}

static u32 compute_next_eventid_offset(struct list_head *h, struct its_ite *ite)
{
        struct its_ite *next;
        u32 next_offset;

        if (list_is_last(&ite->ite_list, h))
                return 0;
        next = list_next_entry(ite, ite_list);
        next_offset = next->event_id - ite->event_id;

        return min_t(u32, next_offset, VITS_ITE_MAX_EVENTID_OFFSET);
}

/**
 * entry_fn_t - Callback called on a table entry restore path
 * @its: its handle
 * @id: id of the entry
 * @entry: pointer to the entry
 * @opaque: pointer to an opaque data
 *
 * Return: < 0 on error, 0 if last element was identified, id offset to next
 * element otherwise
 */
typedef int (*entry_fn_t)(struct vgic_its *its, u32 id, void *entry,
                          void *opaque);

/**
 * scan_its_table - Scan a contiguous table in guest RAM and applies a function
 * to each entry
 *
 * @its: its handle
 * @base: base gpa of the table
 * @size: size of the table in bytes
 * @esz: entry size in bytes
 * @start_id: the ID of the first entry in the table
 * (non zero for 2d level tables)
 * @fn: function to apply on each entry
 *
 * Return: < 0 on error, 0 if last element was identified, 1 otherwise
 * (the last element may not be found on second level tables)
 */
static int scan_its_table(struct vgic_its *its, gpa_t base, int size, u32 esz,
                          int start_id, entry_fn_t fn, void *opaque)
{
        struct kvm *kvm = its->dev->kvm;
        unsigned long len = size;
        int id = start_id;
        gpa_t gpa = base;
        char entry[ESZ_MAX];
        int ret;

        memset(entry, 0, esz);

        while (len > 0) {
                int next_offset;
                size_t byte_offset;

                ret = kvm_read_guest_lock(kvm, gpa, entry, esz);
                if (ret)
                        return ret;

                next_offset = fn(its, id, entry, opaque);
                if (next_offset <= 0)
                        return next_offset;

                byte_offset = next_offset * esz;
                id += next_offset;
                gpa += byte_offset;
                len -= byte_offset;
        }
        return 1;
}

/**
 * vgic_its_save_ite - Save an interrupt translation entry at @gpa
 */
static int vgic_its_save_ite(struct vgic_its *its, struct its_device *dev,
                              struct its_ite *ite, gpa_t gpa, int ite_esz)
{
        struct kvm *kvm = its->dev->kvm;
        u32 next_offset;
        u64 val;

        next_offset = compute_next_eventid_offset(&dev->itt_head, ite);
        val = ((u64)next_offset << KVM_ITS_ITE_NEXT_SHIFT) |
               ((u64)ite->irq->intid << KVM_ITS_ITE_PINTID_SHIFT) |
                ite->collection->collection_id;
        val = cpu_to_le64(val);
        return kvm_write_guest_lock(kvm, gpa, &val, ite_esz);
}

/**
 * vgic_its_restore_ite - restore an interrupt translation entry
 * @event_id: id used for indexing
 * @ptr: pointer to the ITE entry
 * @opaque: pointer to the its_device
 */
static int vgic_its_restore_ite(struct vgic_its *its, u32 event_id,
                                void *ptr, void *opaque)
{
        struct its_device *dev = (struct its_device *)opaque;
        struct its_collection *collection;
        struct kvm *kvm = its->dev->kvm;
        struct kvm_vcpu *vcpu = NULL;
        u64 val;
        u64 *p = (u64 *)ptr;
        struct vgic_irq *irq;
        u32 coll_id, lpi_id;
        struct its_ite *ite;
        u32 offset;

        val = *p;

        val = le64_to_cpu(val);

        coll_id = val & KVM_ITS_ITE_ICID_MASK;
        lpi_id = (val & KVM_ITS_ITE_PINTID_MASK) >> KVM_ITS_ITE_PINTID_SHIFT;

        if (!lpi_id)
                return 1; /* invalid entry, no choice but to scan next entry */

        if (lpi_id < VGIC_MIN_LPI)
                return -EINVAL;

        offset = val >> KVM_ITS_ITE_NEXT_SHIFT;
        if (event_id + offset >= BIT_ULL(dev->num_eventid_bits))
                return -EINVAL;

        collection = find_collection(its, coll_id);
        if (!collection)
                return -EINVAL;

        ite = vgic_its_alloc_ite(dev, collection, event_id);
        if (IS_ERR(ite))
                return PTR_ERR(ite);

        if (its_is_collection_mapped(collection))
                vcpu = kvm_get_vcpu(kvm, collection->target_addr);

        irq = vgic_add_lpi(kvm, lpi_id, vcpu);
        if (IS_ERR(irq))
                return PTR_ERR(irq);
        ite->irq = irq;

        return offset;
}

static int vgic_its_ite_cmp(void *priv, const struct list_head *a,
                            const struct list_head *b)
{
        struct its_ite *itea = container_of(a, struct its_ite, ite_list);
        struct its_ite *iteb = container_of(b, struct its_ite, ite_list);

        if (itea->event_id < iteb->event_id)
                return -1;
        else
                return 1;
}

static int vgic_its_save_itt(struct vgic_its *its, struct its_device *device)
{
        const struct vgic_its_abi *abi = vgic_its_get_abi(its);
        gpa_t base = device->itt_addr;
        struct its_ite *ite;
        int ret;
        int ite_esz = abi->ite_esz;

        list_sort(NULL, &device->itt_head, vgic_its_ite_cmp);

        list_for_each_entry(ite, &device->itt_head, ite_list) {
                gpa_t gpa = base + ite->event_id * ite_esz;

                /*
                 * If an LPI carries the HW bit, this means that this
                 * interrupt is controlled by GICv4, and we do not
                 * have direct access to that state without GICv4.1.
                 * Let's simply fail the save operation...
                 */
                if (ite->irq->hw && !kvm_vgic_global_state.has_gicv4_1)
                        return -EACCES;

                ret = vgic_its_save_ite(its, device, ite, gpa, ite_esz);
                if (ret)
                        return ret;
        }
        return 0;
}

/**
 * vgic_its_restore_itt - restore the ITT of a device
 *
 * @its: its handle
 * @dev: device handle
 *
 * Return 0 on success, < 0 on error
 */
static int vgic_its_restore_itt(struct vgic_its *its, struct its_device *dev)
{
        const struct vgic_its_abi *abi = vgic_its_get_abi(its);
        gpa_t base = dev->itt_addr;
        int ret;
        int ite_esz = abi->ite_esz;
        size_t max_size = BIT_ULL(dev->num_eventid_bits) * ite_esz;

        ret = scan_its_table(its, base, max_size, ite_esz, 0,
                             vgic_its_restore_ite, dev);

        /* scan_its_table returns +1 if all ITEs are invalid */
        if (ret > 0)
                ret = 0;

        return ret;
}

/**
 * vgic_its_save_dte - Save a device table entry at a given GPA
 *
 * @its: ITS handle
 * @dev: ITS device
 * @ptr: GPA
 */
static int vgic_its_save_dte(struct vgic_its *its, struct its_device *dev,
                             gpa_t ptr, int dte_esz)
{
        struct kvm *kvm = its->dev->kvm;
        u64 val, itt_addr_field;
        u32 next_offset;

        itt_addr_field = dev->itt_addr >> 8;
        next_offset = compute_next_devid_offset(&its->device_list, dev);
        val = (1ULL << KVM_ITS_DTE_VALID_SHIFT |
               ((u64)next_offset << KVM_ITS_DTE_NEXT_SHIFT) |
               (itt_addr_field << KVM_ITS_DTE_ITTADDR_SHIFT) |
                (dev->num_eventid_bits - 1));
        val = cpu_to_le64(val);
        return kvm_write_guest_lock(kvm, ptr, &val, dte_esz);
}

/**
 * vgic_its_restore_dte - restore a device table entry
 *
 * @its: its handle
 * @id: device id the DTE corresponds to
 * @ptr: kernel VA where the 8 byte DTE is located
 * @opaque: unused
 *
 * Return: < 0 on error, 0 if the dte is the last one, id offset to the
 * next dte otherwise
 */
static int vgic_its_restore_dte(struct vgic_its *its, u32 id,
                                void *ptr, void *opaque)
{
        struct its_device *dev;
        gpa_t itt_addr;
        u8 num_eventid_bits;
        u64 entry = *(u64 *)ptr;
        bool valid;
        u32 offset;
        int ret;

        entry = le64_to_cpu(entry);

        valid = entry >> KVM_ITS_DTE_VALID_SHIFT;
        num_eventid_bits = (entry & KVM_ITS_DTE_SIZE_MASK) + 1;
        itt_addr = ((entry & KVM_ITS_DTE_ITTADDR_MASK)
                        >> KVM_ITS_DTE_ITTADDR_SHIFT) << 8;

        if (!valid)
                return 1;

        /* dte entry is valid */
        offset = (entry & KVM_ITS_DTE_NEXT_MASK) >> KVM_ITS_DTE_NEXT_SHIFT;

        dev = vgic_its_alloc_device(its, id, itt_addr, num_eventid_bits);
        if (IS_ERR(dev))
                return PTR_ERR(dev);

        ret = vgic_its_restore_itt(its, dev);
        if (ret) {
                vgic_its_free_device(its->dev->kvm, dev);
                return ret;
        }

        return offset;
}

static int vgic_its_device_cmp(void *priv, const struct list_head *a,
                               const struct list_head *b)
{
        struct its_device *deva = container_of(a, struct its_device, dev_list);
        struct its_device *devb = container_of(b, struct its_device, dev_list);

        if (deva->device_id < devb->device_id)
                return -1;
        else
                return 1;
}

/**
 * vgic_its_save_device_tables - Save the device table and all ITT
 * into guest RAM
 *
 * L1/L2 handling is hidden by vgic_its_check_id() helper which directly
 * returns the GPA of the device entry
 */
static int vgic_its_save_device_tables(struct vgic_its *its)
{
        const struct vgic_its_abi *abi = vgic_its_get_abi(its);
        u64 baser = its->baser_device_table;
        struct its_device *dev;
        int dte_esz = abi->dte_esz;

        if (!(baser & GITS_BASER_VALID))
                return 0;

        list_sort(NULL, &its->device_list, vgic_its_device_cmp);

        list_for_each_entry(dev, &its->device_list, dev_list) {
                int ret;
                gpa_t eaddr;

                if (!vgic_its_check_id(its, baser,
                                       dev->device_id, &eaddr))
                        return -EINVAL;

                ret = vgic_its_save_itt(its, dev);
                if (ret)
                        return ret;

                ret = vgic_its_save_dte(its, dev, eaddr, dte_esz);
                if (ret)
                        return ret;
        }
        return 0;
}

/**
 * handle_l1_dte - callback used for L1 device table entries (2 stage case)
 *
 * @its: its handle
 * @id: index of the entry in the L1 table
 * @addr: kernel VA
 * @opaque: unused
 *
 * L1 table entries are scanned by steps of 1 entry
 * Return < 0 if error, 0 if last dte was found when scanning the L2
 * table, +1 otherwise (meaning next L1 entry must be scanned)
 */
static int handle_l1_dte(struct vgic_its *its, u32 id, void *addr,
                         void *opaque)
{
        const struct vgic_its_abi *abi = vgic_its_get_abi(its);
        int l2_start_id = id * (SZ_64K / abi->dte_esz);
        u64 entry = *(u64 *)addr;
        int dte_esz = abi->dte_esz;
        gpa_t gpa;
        int ret;

        entry = le64_to_cpu(entry);

        if (!(entry & KVM_ITS_L1E_VALID_MASK))
                return 1;

        gpa = entry & KVM_ITS_L1E_ADDR_MASK;

        ret = scan_its_table(its, gpa, SZ_64K, dte_esz,
                             l2_start_id, vgic_its_restore_dte, NULL);

        return ret;
}

/**
 * vgic_its_restore_device_tables - Restore the device table and all ITT
 * from guest RAM to internal data structs
 */
static int vgic_its_restore_device_tables(struct vgic_its *its)
{
        const struct vgic_its_abi *abi = vgic_its_get_abi(its);
        u64 baser = its->baser_device_table;
        int l1_esz, ret;
        int l1_tbl_size = GITS_BASER_NR_PAGES(baser) * SZ_64K;
        gpa_t l1_gpa;

        if (!(baser & GITS_BASER_VALID))
                return 0;

        l1_gpa = GITS_BASER_ADDR_48_to_52(baser);

        if (baser & GITS_BASER_INDIRECT) {
                l1_esz = GITS_LVL1_ENTRY_SIZE;
                ret = scan_its_table(its, l1_gpa, l1_tbl_size, l1_esz, 0,
                                     handle_l1_dte, NULL);
        } else {
                l1_esz = abi->dte_esz;
                ret = scan_its_table(its, l1_gpa, l1_tbl_size, l1_esz, 0,
                                     vgic_its_restore_dte, NULL);
        }

        /* scan_its_table returns +1 if all entries are invalid */
        if (ret > 0)
                ret = 0;

        return ret;
}

static int vgic_its_save_cte(struct vgic_its *its,
                             struct its_collection *collection,
                             gpa_t gpa, int esz)
{
        u64 val;

        val = (1ULL << KVM_ITS_CTE_VALID_SHIFT |
               ((u64)collection->target_addr << KVM_ITS_CTE_RDBASE_SHIFT) |
               collection->collection_id);
        val = cpu_to_le64(val);
        return kvm_write_guest_lock(its->dev->kvm, gpa, &val, esz);
}

static int vgic_its_restore_cte(struct vgic_its *its, gpa_t gpa, int esz)
{
        struct its_collection *collection;
        struct kvm *kvm = its->dev->kvm;
        u32 target_addr, coll_id;
        u64 val;
        int ret;

        BUG_ON(esz > sizeof(val));
        ret = kvm_read_guest_lock(kvm, gpa, &val, esz);
        if (ret)
                return ret;
        val = le64_to_cpu(val);
        if (!(val & KVM_ITS_CTE_VALID_MASK))
                return 0;

        target_addr = (u32)(val >> KVM_ITS_CTE_RDBASE_SHIFT);
        coll_id = val & KVM_ITS_CTE_ICID_MASK;

        if (target_addr != COLLECTION_NOT_MAPPED &&
            target_addr >= atomic_read(&kvm->online_vcpus))
                return -EINVAL;

        collection = find_collection(its, coll_id);
        if (collection)
                return -EEXIST;
        ret = vgic_its_alloc_collection(its, &collection, coll_id);
        if (ret)
                return ret;
        collection->target_addr = target_addr;
        return 1;
}

/**
 * vgic_its_save_collection_table - Save the collection table into
 * guest RAM
 */
static int vgic_its_save_collection_table(struct vgic_its *its)
{
        const struct vgic_its_abi *abi = vgic_its_get_abi(its);
        u64 baser = its->baser_coll_table;
        gpa_t gpa = GITS_BASER_ADDR_48_to_52(baser);
        struct its_collection *collection;
        u64 val;
        size_t max_size, filled = 0;
        int ret, cte_esz = abi->cte_esz;

        if (!(baser & GITS_BASER_VALID))
                return 0;

        max_size = GITS_BASER_NR_PAGES(baser) * SZ_64K;

        list_for_each_entry(collection, &its->collection_list, coll_list) {
                ret = vgic_its_save_cte(its, collection, gpa, cte_esz);
                if (ret)
                        return ret;
                gpa += cte_esz;
                filled += cte_esz;
        }

        if (filled == max_size)
                return 0;

        /*
         * table is not fully filled, add a last dummy element
         * with valid bit unset
         */
        val = 0;
        BUG_ON(cte_esz > sizeof(val));
        ret = kvm_write_guest_lock(its->dev->kvm, gpa, &val, cte_esz);
        return ret;
}

/**
 * vgic_its_restore_collection_table - reads the collection table
 * in guest memory and restores the ITS internal state. Requires the
 * BASER registers to be restored before.
 */
static int vgic_its_restore_collection_table(struct vgic_its *its)
{
        const struct vgic_its_abi *abi = vgic_its_get_abi(its);
        u64 baser = its->baser_coll_table;
        int cte_esz = abi->cte_esz;
        size_t max_size, read = 0;
        gpa_t gpa;
        int ret;

        if (!(baser & GITS_BASER_VALID))
                return 0;

        gpa = GITS_BASER_ADDR_48_to_52(baser);

        max_size = GITS_BASER_NR_PAGES(baser) * SZ_64K;

        while (read < max_size) {
                ret = vgic_its_restore_cte(its, gpa, cte_esz);
                if (ret <= 0)
                        break;
                gpa += cte_esz;
                read += cte_esz;
        }

        if (ret > 0)
                return 0;

        return ret;
}

/**
 * vgic_its_save_tables_v0 - Save the ITS tables into guest ARM
 * according to v0 ABI
 */
static int vgic_its_save_tables_v0(struct vgic_its *its)
{
        int ret;

        ret = vgic_its_save_device_tables(its);
        if (ret)
                return ret;

        return vgic_its_save_collection_table(its);
}

/**
 * vgic_its_restore_tables_v0 - Restore the ITS tables from guest RAM
 * to internal data structs according to V0 ABI
 *
 */
static int vgic_its_restore_tables_v0(struct vgic_its *its)
{
        int ret;

        ret = vgic_its_restore_collection_table(its);
        if (ret)
                return ret;

        return vgic_its_restore_device_tables(its);
}

static int vgic_its_commit_v0(struct vgic_its *its)
{
        const struct vgic_its_abi *abi;

        abi = vgic_its_get_abi(its);
        its->baser_coll_table &= ~GITS_BASER_ENTRY_SIZE_MASK;
        its->baser_device_table &= ~GITS_BASER_ENTRY_SIZE_MASK;

        its->baser_coll_table |= (GIC_ENCODE_SZ(abi->cte_esz, 5)
                                        << GITS_BASER_ENTRY_SIZE_SHIFT);

        its->baser_device_table |= (GIC_ENCODE_SZ(abi->dte_esz, 5)
                                        << GITS_BASER_ENTRY_SIZE_SHIFT);
        return 0;
}

static void vgic_its_reset(struct kvm *kvm, struct vgic_its *its)
{
        /* We need to keep the ABI specific field values */
        its->baser_coll_table &= ~GITS_BASER_VALID;
        its->baser_device_table &= ~GITS_BASER_VALID;
        its->cbaser = 0;
        its->creadr = 0;
        its->cwriter = 0;
        its->enabled = 0;
        vgic_its_free_device_list(kvm, its);
        vgic_its_free_collection_list(kvm, its);
}

static int vgic_its_has_attr(struct kvm_device *dev,
                             struct kvm_device_attr *attr)
{
        switch (attr->group) {
        case KVM_DEV_ARM_VGIC_GRP_ADDR:
                switch (attr->attr) {
                case KVM_VGIC_ITS_ADDR_TYPE:
                        return 0;
                }
                break;
        case KVM_DEV_ARM_VGIC_GRP_CTRL:
                switch (attr->attr) {
                case KVM_DEV_ARM_VGIC_CTRL_INIT:
                        return 0;
                case KVM_DEV_ARM_ITS_CTRL_RESET:
                        return 0;
                case KVM_DEV_ARM_ITS_SAVE_TABLES:
                        return 0;
                case KVM_DEV_ARM_ITS_RESTORE_TABLES:
                        return 0;
                }
                break;
        case KVM_DEV_ARM_VGIC_GRP_ITS_REGS:
                return vgic_its_has_attr_regs(dev, attr);
        }
        return -ENXIO;
}

static int vgic_its_ctrl(struct kvm *kvm, struct vgic_its *its, u64 attr)
{
        const struct vgic_its_abi *abi = vgic_its_get_abi(its);
        int ret = 0;

        if (attr == KVM_DEV_ARM_VGIC_CTRL_INIT) /* Nothing to do */
                return 0;

        mutex_lock(&kvm->lock);
        mutex_lock(&its->its_lock);

        if (!lock_all_vcpus(kvm)) {
                mutex_unlock(&its->its_lock);
                mutex_unlock(&kvm->lock);
                return -EBUSY;
        }

        switch (attr) {
        case KVM_DEV_ARM_ITS_CTRL_RESET:
                vgic_its_reset(kvm, its);
                break;
        case KVM_DEV_ARM_ITS_SAVE_TABLES:
                ret = abi->save_tables(its);
                break;
        case KVM_DEV_ARM_ITS_RESTORE_TABLES:
                ret = abi->restore_tables(its);
                break;
        }

        unlock_all_vcpus(kvm);
        mutex_unlock(&its->its_lock);
        mutex_unlock(&kvm->lock);
        return ret;
}

static int vgic_its_set_attr(struct kvm_device *dev,
                             struct kvm_device_attr *attr)
{
        struct vgic_its *its = dev->private;
        int ret;

        switch (attr->group) {
        case KVM_DEV_ARM_VGIC_GRP_ADDR: {
                u64 __user *uaddr = (u64 __user *)(long)attr->addr;
                unsigned long type = (unsigned long)attr->attr;
                u64 addr;

                if (type != KVM_VGIC_ITS_ADDR_TYPE)
                        return -ENODEV;

                if (copy_from_user(&addr, uaddr, sizeof(addr)))
                        return -EFAULT;

                ret = vgic_check_ioaddr(dev->kvm, &its->vgic_its_base,
                                        addr, SZ_64K);
                if (ret)
                        return ret;

                return vgic_register_its_iodev(dev->kvm, its, addr);
        }
        case KVM_DEV_ARM_VGIC_GRP_CTRL:
                return vgic_its_ctrl(dev->kvm, its, attr->attr);
        case KVM_DEV_ARM_VGIC_GRP_ITS_REGS: {
                u64 __user *uaddr = (u64 __user *)(long)attr->addr;
                u64 reg;

                if (get_user(reg, uaddr))
                        return -EFAULT;

                return vgic_its_attr_regs_access(dev, attr, &reg, true);
        }
        }
        return -ENXIO;
}

static int vgic_its_get_attr(struct kvm_device *dev,
                             struct kvm_device_attr *attr)
{
        switch (attr->group) {
        case KVM_DEV_ARM_VGIC_GRP_ADDR: {
                struct vgic_its *its = dev->private;
                u64 addr = its->vgic_its_base;
                u64 __user *uaddr = (u64 __user *)(long)attr->addr;
                unsigned long type = (unsigned long)attr->attr;

                if (type != KVM_VGIC_ITS_ADDR_TYPE)
                        return -ENODEV;

                if (copy_to_user(uaddr, &addr, sizeof(addr)))
                        return -EFAULT;
                break;
        }
        case KVM_DEV_ARM_VGIC_GRP_ITS_REGS: {
                u64 __user *uaddr = (u64 __user *)(long)attr->addr;
                u64 reg;
                int ret;

                ret = vgic_its_attr_regs_access(dev, attr, &reg, false);
                if (ret)
                        return ret;
                return put_user(reg, uaddr);
        }
        default:
                return -ENXIO;
        }

        return 0;
}

static struct kvm_device_ops kvm_arm_vgic_its_ops = {
        .name = "kvm-arm-vgic-its",
        .create = vgic_its_create,
        .destroy = vgic_its_destroy,
        .set_attr = vgic_its_set_attr,
        .get_attr = vgic_its_get_attr,
        .has_attr = vgic_its_has_attr,
};

int kvm_vgic_register_its_device(void)
{
        return kvm_register_device_ops(&kvm_arm_vgic_its_ops,
                                       KVM_DEV_TYPE_ARM_VGIC_ITS);
}