#include <linux/interrupt.h>
#include <linux/dmar.h>
#include <linux/spinlock.h>
#include <linux/slab.h>
#include <linux/jiffies.h>
#include <linux/hpet.h>
#include <linux/pci.h>
#include <linux/irq.h>
#include <linux/intel-iommu.h>
#include <linux/acpi.h>
#include <asm/io_apic.h>
#include <asm/smp.h>
#include <asm/cpu.h>
#include <asm/irq_remapping.h>
#include <asm/pci-direct.h>
#include <asm/msidef.h>

#include "irq_remapping.h"

struct ioapic_scope {
        struct intel_iommu *iommu;
        unsigned int id;
        unsigned int bus;       /* PCI bus number */
        unsigned int devfn;     /* PCI devfn number */
};

struct hpet_scope {
        struct intel_iommu *iommu;
        u8 id;
        unsigned int bus;
        unsigned int devfn;
};

#define IR_X2APIC_MODE(mode) (mode ? (1 << 11) : 0)
#define IRTE_DEST(dest) ((x2apic_mode) ? dest : dest << 8)

static struct ioapic_scope ir_ioapic[MAX_IO_APICS];
static struct hpet_scope ir_hpet[MAX_HPET_TBS];

/*
 * Lock ordering:
 * ->dmar_global_lock
 *      ->irq_2_ir_lock
 *              ->qi->q_lock
 *      ->iommu->register_lock
 * Note:
 * intel_irq_remap_ops.{supported,prepare,enable,disable,reenable} are called
 * in single-threaded environment with interrupt disabled, so no need to tabke
 * the dmar_global_lock.
 */
static DEFINE_RAW_SPINLOCK(irq_2_ir_lock);

static int __init parse_ioapics_under_ir(void);

static struct irq_2_iommu *irq_2_iommu(unsigned int irq)
{
        struct irq_cfg *cfg = irq_cfg(irq);
        return cfg ? &cfg->irq_2_iommu : NULL;
}

static int get_irte(int irq, struct irte *entry)
{
        struct irq_2_iommu *irq_iommu = irq_2_iommu(irq);
        unsigned long flags;
        int index;

        if (!entry || !irq_iommu)
                return -1;

        raw_spin_lock_irqsave(&irq_2_ir_lock, flags);

        if (unlikely(!irq_iommu->iommu)) {
                raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);
                return -1;
        }

        index = irq_iommu->irte_index + irq_iommu->sub_handle;
        *entry = *(irq_iommu->iommu->ir_table->base + index);

        raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);
        return 0;
}

static int alloc_irte(struct intel_iommu *iommu, int irq, u16 count)
{
        struct ir_table *table = iommu->ir_table;
        struct irq_2_iommu *irq_iommu = irq_2_iommu(irq);
        struct irq_cfg *cfg = irq_cfg(irq);
        unsigned int mask = 0;
        unsigned long flags;
        int index;

        if (!count || !irq_iommu)
                return -1;

        if (count > 1) {
                count = __roundup_pow_of_two(count);
                mask = ilog2(count);
        }

        if (mask > ecap_max_handle_mask(iommu->ecap)) {
                printk(KERN_ERR
                       "Requested mask %x exceeds the max invalidation handle"
                       " mask value %Lx\n", mask,
                       ecap_max_handle_mask(iommu->ecap));
                return -1;
        }

        raw_spin_lock_irqsave(&irq_2_ir_lock, flags);
        index = bitmap_find_free_region(table->bitmap,
                                        INTR_REMAP_TABLE_ENTRIES, mask);
        if (index < 0) {
                pr_warn("IR%d: can't allocate an IRTE\n", iommu->seq_id);
        } else {
                cfg->remapped = 1;
                irq_iommu->iommu = iommu;
                irq_iommu->irte_index =  index;
                irq_iommu->sub_handle = 0;
                irq_iommu->irte_mask = mask;
        }
        raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);

        return index;
}

static int qi_flush_iec(struct intel_iommu *iommu, int index, int mask)
{
        struct qi_desc desc;

        desc.low = QI_IEC_IIDEX(index) | QI_IEC_TYPE | QI_IEC_IM(mask)
                   | QI_IEC_SELECTIVE;
        desc.high = 0;

        return qi_submit_sync(&desc, iommu);
}

static int map_irq_to_irte_handle(int irq, u16 *sub_handle)
{
        struct irq_2_iommu *irq_iommu = irq_2_iommu(irq);
        unsigned long flags;
        int index;

        if (!irq_iommu)
                return -1;

        raw_spin_lock_irqsave(&irq_2_ir_lock, flags);
        *sub_handle = irq_iommu->sub_handle;
        index = irq_iommu->irte_index;
        raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);
        return index;
}

static int set_irte_irq(int irq, struct intel_iommu *iommu, u16 index, u16 subhandle)
{
        struct irq_2_iommu *irq_iommu = irq_2_iommu(irq);
        struct irq_cfg *cfg = irq_cfg(irq);
        unsigned long flags;

        if (!irq_iommu)
                return -1;

        raw_spin_lock_irqsave(&irq_2_ir_lock, flags);

        cfg->remapped = 1;
        irq_iommu->iommu = iommu;
        irq_iommu->irte_index = index;
        irq_iommu->sub_handle = subhandle;
        irq_iommu->irte_mask = 0;

        raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);

        return 0;
}

static int modify_irte(int irq, struct irte *irte_modified)
{
        struct irq_2_iommu *irq_iommu = irq_2_iommu(irq);
        struct intel_iommu *iommu;
        unsigned long flags;
        struct irte *irte;
        int rc, index;

        if (!irq_iommu)
                return -1;

        raw_spin_lock_irqsave(&irq_2_ir_lock, flags);

        iommu = irq_iommu->iommu;

        index = irq_iommu->irte_index + irq_iommu->sub_handle;
        irte = &iommu->ir_table->base[index];

        set_64bit(&irte->low, irte_modified->low);
        set_64bit(&irte->high, irte_modified->high);
        __iommu_flush_cache(iommu, irte, sizeof(*irte));

        rc = qi_flush_iec(iommu, index, 0);
        raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);

        return rc;
}

static struct intel_iommu *map_hpet_to_ir(u8 hpet_id)
{
        int i;

        for (i = 0; i < MAX_HPET_TBS; i++)
                if (ir_hpet[i].id == hpet_id && ir_hpet[i].iommu)
                        return ir_hpet[i].iommu;
        return NULL;
}

static struct intel_iommu *map_ioapic_to_ir(int apic)
{
        int i;

        for (i = 0; i < MAX_IO_APICS; i++)
                if (ir_ioapic[i].id == apic && ir_ioapic[i].iommu)
                        return ir_ioapic[i].iommu;
        return NULL;
}

static struct intel_iommu *map_dev_to_ir(struct pci_dev *dev)
{
        struct dmar_drhd_unit *drhd;

        drhd = dmar_find_matched_drhd_unit(dev);
        if (!drhd)
                return NULL;

        return drhd->iommu;
}

static int clear_entries(struct irq_2_iommu *irq_iommu)
{
        struct irte *start, *entry, *end;
        struct intel_iommu *iommu;
        int index;

        if (irq_iommu->sub_handle)
                return 0;

        iommu = irq_iommu->iommu;
        index = irq_iommu->irte_index + irq_iommu->sub_handle;

        start = iommu->ir_table->base + index;
        end = start + (1 << irq_iommu->irte_mask);

        for (entry = start; entry < end; entry++) {
                set_64bit(&entry->low, 0);
                set_64bit(&entry->high, 0);
        }
        bitmap_release_region(iommu->ir_table->bitmap, index,
                              irq_iommu->irte_mask);

        return qi_flush_iec(iommu, index, irq_iommu->irte_mask);
}

static int free_irte(int irq)
{
        struct irq_2_iommu *irq_iommu = irq_2_iommu(irq);
        unsigned long flags;
        int rc;

        if (!irq_iommu)
                return -1;

        raw_spin_lock_irqsave(&irq_2_ir_lock, flags);

        rc = clear_entries(irq_iommu);

        irq_iommu->iommu = NULL;
        irq_iommu->irte_index = 0;
        irq_iommu->sub_handle = 0;
        irq_iommu->irte_mask = 0;

        raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);

        return rc;
}

/*
 * source validation type
 */
#define SVT_NO_VERIFY           0x0  /* no verification is required */
#define SVT_VERIFY_SID_SQ       0x1  /* verify using SID and SQ fields */
#define SVT_VERIFY_BUS          0x2  /* verify bus of request-id */

/*
 * source-id qualifier
 */
#define SQ_ALL_16       0x0  /* verify all 16 bits of request-id */
#define SQ_13_IGNORE_1  0x1  /* verify most significant 13 bits, ignore
                              * the third least significant bit
                              */
#define SQ_13_IGNORE_2  0x2  /* verify most significant 13 bits, ignore
                              * the second and third least significant bits
                              */
#define SQ_13_IGNORE_3  0x3  /* verify most significant 13 bits, ignore
                              * the least three significant bits
                              */

/*
 * set SVT, SQ and SID fields of irte to verify
 * source ids of interrupt requests
 */
static void set_irte_sid(struct irte *irte, unsigned int svt,
                         unsigned int sq, unsigned int sid)
{
        if (disable_sourceid_checking)
                svt = SVT_NO_VERIFY;
        irte->svt = svt;
        irte->sq = sq;
        irte->sid = sid;
}

static int set_ioapic_sid(struct irte *irte, int apic)
{
        int i;
        u16 sid = 0;

        if (!irte)
                return -1;

        down_read(&dmar_global_lock);
        for (i = 0; i < MAX_IO_APICS; i++) {
                if (ir_ioapic[i].iommu && ir_ioapic[i].id == apic) {
                        sid = (ir_ioapic[i].bus << 8) | ir_ioapic[i].devfn;
                        break;
                }
        }
        up_read(&dmar_global_lock);

        if (sid == 0) {
                pr_warning("Failed to set source-id of IOAPIC (%d)\n", apic);
                return -1;
        }

        set_irte_sid(irte, SVT_VERIFY_SID_SQ, SQ_ALL_16, sid);

        return 0;
}

static int set_hpet_sid(struct irte *irte, u8 id)
{
        int i;
        u16 sid = 0;

        if (!irte)
                return -1;

        down_read(&dmar_global_lock);
        for (i = 0; i < MAX_HPET_TBS; i++) {
                if (ir_hpet[i].iommu && ir_hpet[i].id == id) {
                        sid = (ir_hpet[i].bus << 8) | ir_hpet[i].devfn;
                        break;
                }
        }
        up_read(&dmar_global_lock);

        if (sid == 0) {
                pr_warning("Failed to set source-id of HPET block (%d)\n", id);
                return -1;
        }

        /*
         * Should really use SQ_ALL_16. Some platforms are broken.
         * While we figure out the right quirks for these broken platforms, use
         * SQ_13_IGNORE_3 for now.
         */
        set_irte_sid(irte, SVT_VERIFY_SID_SQ, SQ_13_IGNORE_3, sid);

        return 0;
}

struct set_msi_sid_data {
        struct pci_dev *pdev;
        u16 alias;
};

static int set_msi_sid_cb(struct pci_dev *pdev, u16 alias, void *opaque)
{
        struct set_msi_sid_data *data = opaque;

        data->pdev = pdev;
        data->alias = alias;

        return 0;
}

static int set_msi_sid(struct irte *irte, struct pci_dev *dev)
{
        struct set_msi_sid_data data;

        if (!irte || !dev)
                return -1;

        pci_for_each_dma_alias(dev, set_msi_sid_cb, &data);

        /*
         * DMA alias provides us with a PCI device and alias.  The only case
         * where the it will return an alias on a different bus than the
         * device is the case of a PCIe-to-PCI bridge, where the alias is for
         * the subordinate bus.  In this case we can only verify the bus.
         *
         * If the alias device is on a different bus than our source device
         * then we have a topology based alias, use it.
         *
         * Otherwise, the alias is for a device DMA quirk and we cannot
         * assume that MSI uses the same requester ID.  Therefore use the
         * original device.
         */
        if (PCI_BUS_NUM(data.alias) != data.pdev->bus->number)
                set_irte_sid(irte, SVT_VERIFY_BUS, SQ_ALL_16,
                             PCI_DEVID(PCI_BUS_NUM(data.alias),
                                       dev->bus->number));
        else if (data.pdev->bus->number != dev->bus->number)
                set_irte_sid(irte, SVT_VERIFY_SID_SQ, SQ_ALL_16, data.alias);
        else
                set_irte_sid(irte, SVT_VERIFY_SID_SQ, SQ_ALL_16,
                             PCI_DEVID(dev->bus->number, dev->devfn));

        return 0;
}

static void iommu_set_irq_remapping(struct intel_iommu *iommu, int mode)
{
        u64 addr;
        u32 sts;
        unsigned long flags;

        addr = virt_to_phys((void *)iommu->ir_table->base);

        raw_spin_lock_irqsave(&iommu->register_lock, flags);

        dmar_writeq(iommu->reg + DMAR_IRTA_REG,
                    (addr) | IR_X2APIC_MODE(mode) | INTR_REMAP_TABLE_REG_SIZE);

        /* Set interrupt-remapping table pointer */
        writel(iommu->gcmd | DMA_GCMD_SIRTP, iommu->reg + DMAR_GCMD_REG);

        IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG,
                      readl, (sts & DMA_GSTS_IRTPS), sts);
        raw_spin_unlock_irqrestore(&iommu->register_lock, flags);

        /*
         * global invalidation of interrupt entry cache before enabling
         * interrupt-remapping.
         */
        qi_global_iec(iommu);

        raw_spin_lock_irqsave(&iommu->register_lock, flags);

        /* Enable interrupt-remapping */
        iommu->gcmd |= DMA_GCMD_IRE;
        iommu->gcmd &= ~DMA_GCMD_CFI;  /* Block compatibility-format MSIs */
        writel(iommu->gcmd, iommu->reg + DMAR_GCMD_REG);

        IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG,
                      readl, (sts & DMA_GSTS_IRES), sts);

        /*
         * With CFI clear in the Global Command register, we should be
         * protected from dangerous (i.e. compatibility) interrupts
         * regardless of x2apic status.  Check just to be sure.
         */
        if (sts & DMA_GSTS_CFIS)
                WARN(1, KERN_WARNING
                        "Compatibility-format IRQs enabled despite intr remapping;\n"
                        "you are vulnerable to IRQ injection.\n");

        raw_spin_unlock_irqrestore(&iommu->register_lock, flags);
}

static int intel_setup_irq_remapping(struct intel_iommu *iommu)
{
        struct ir_table *ir_table;
        struct page *pages;
        unsigned long *bitmap;

        if (iommu->ir_table)
                return 0;

        ir_table = kzalloc(sizeof(struct ir_table), GFP_ATOMIC);
        if (!ir_table)
                return -ENOMEM;

        pages = alloc_pages_node(iommu->node, GFP_ATOMIC | __GFP_ZERO,
                                 INTR_REMAP_PAGE_ORDER);

        if (!pages) {
                pr_err("IR%d: failed to allocate pages of order %d\n",
                       iommu->seq_id, INTR_REMAP_PAGE_ORDER);
                goto out_free_table;
        }

        bitmap = kcalloc(BITS_TO_LONGS(INTR_REMAP_TABLE_ENTRIES),
                         sizeof(long), GFP_ATOMIC);
        if (bitmap == NULL) {
                pr_err("IR%d: failed to allocate bitmap\n", iommu->seq_id);
                goto out_free_pages;
        }

        ir_table->base = page_address(pages);
        ir_table->bitmap = bitmap;
        iommu->ir_table = ir_table;
        return 0;

out_free_pages:
        __free_pages(pages, INTR_REMAP_PAGE_ORDER);
out_free_table:
        kfree(ir_table);
        return -ENOMEM;
}

static void intel_teardown_irq_remapping(struct intel_iommu *iommu)
{
        if (iommu && iommu->ir_table) {
                free_pages((unsigned long)iommu->ir_table->base,
                           INTR_REMAP_PAGE_ORDER);
                kfree(iommu->ir_table->bitmap);
                kfree(iommu->ir_table);
                iommu->ir_table = NULL;
        }
}

/*
 * Disable Interrupt Remapping.
 */
static void iommu_disable_irq_remapping(struct intel_iommu *iommu)
{
        unsigned long flags;
        u32 sts;

        if (!ecap_ir_support(iommu->ecap))
                return;

        /*
         * global invalidation of interrupt entry cache before disabling
         * interrupt-remapping.
         */
        qi_global_iec(iommu);

        raw_spin_lock_irqsave(&iommu->register_lock, flags);

        sts = dmar_readq(iommu->reg + DMAR_GSTS_REG);
        if (!(sts & DMA_GSTS_IRES))
                goto end;

        iommu->gcmd &= ~DMA_GCMD_IRE;
        writel(iommu->gcmd, iommu->reg + DMAR_GCMD_REG);

        IOMMU_WAIT_OP(iommu, DMAR_GSTS_REG,
                      readl, !(sts & DMA_GSTS_IRES), sts);

end:
        raw_spin_unlock_irqrestore(&iommu->register_lock, flags);
}

static int __init dmar_x2apic_optout(void)
{
        struct acpi_table_dmar *dmar;
        dmar = (struct acpi_table_dmar *)dmar_tbl;
        if (!dmar || no_x2apic_optout)
                return 0;
        return dmar->flags & DMAR_X2APIC_OPT_OUT;
}

static int __init intel_irq_remapping_supported(void)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;

        if (disable_irq_remap)
                return 0;
        if (irq_remap_broken) {
                printk(KERN_WARNING
                        "This system BIOS has enabled interrupt remapping\n"
                        "on a chipset that contains an erratum making that\n"
                        "feature unstable.  To maintain system stability\n"
                        "interrupt remapping is being disabled.  Please\n"
                        "contact your BIOS vendor for an update\n");
                add_taint(TAINT_FIRMWARE_WORKAROUND, LOCKDEP_STILL_OK);
                disable_irq_remap = 1;
                return 0;
        }

        if (!dmar_ir_support())
                return 0;

        for_each_iommu(iommu, drhd)
                if (!ecap_ir_support(iommu->ecap))
                        return 0;

        return 1;
}

static int __init intel_enable_irq_remapping(void)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;
        bool x2apic_present;
        int setup = 0;
        int eim = 0;

        x2apic_present = x2apic_supported();

        if (parse_ioapics_under_ir() != 1) {
                printk(KERN_INFO "Not enable interrupt remapping\n");
                goto error;
        }

        if (x2apic_present) {
                pr_info("Queued invalidation will be enabled to support x2apic and Intr-remapping.\n");

                eim = !dmar_x2apic_optout();
                if (!eim)
                        printk(KERN_WARNING
                                "Your BIOS is broken and requested that x2apic be disabled.\n"
                                "This will slightly decrease performance.\n"
                                "Use 'intremap=no_x2apic_optout' to override BIOS request.\n");
        }

        for_each_iommu(iommu, drhd) {
                /*
                 * If the queued invalidation is already initialized,
                 * shouldn't disable it.
                 */
                if (iommu->qi)
                        continue;

                /*
                 * Clear previous faults.
                 */
                dmar_fault(-1, iommu);

                /*
                 * Disable intr remapping and queued invalidation, if already
                 * enabled prior to OS handover.
                 */
                iommu_disable_irq_remapping(iommu);

                dmar_disable_qi(iommu);
        }

        /*
         * check for the Interrupt-remapping support
         */
        for_each_iommu(iommu, drhd) {
                if (!ecap_ir_support(iommu->ecap))
                        continue;

                if (eim && !ecap_eim_support(iommu->ecap)) {
                        printk(KERN_INFO "DRHD %Lx: EIM not supported by DRHD, "
                               " ecap %Lx\n", drhd->reg_base_addr, iommu->ecap);
                        goto error;
                }
        }

        /*
         * Enable queued invalidation for all the DRHD's.
         */
        for_each_iommu(iommu, drhd) {
                int ret = dmar_enable_qi(iommu);

                if (ret) {
                        printk(KERN_ERR "DRHD %Lx: failed to enable queued, "
                               " invalidation, ecap %Lx, ret %d\n",
                               drhd->reg_base_addr, iommu->ecap, ret);
                        goto error;
                }
        }

        /*
         * Setup Interrupt-remapping for all the DRHD's now.
         */
        for_each_iommu(iommu, drhd) {
                if (!ecap_ir_support(iommu->ecap))
                        continue;

                if (intel_setup_irq_remapping(iommu))
                        goto error;

                iommu_set_irq_remapping(iommu, eim);
                setup = 1;
        }

        if (!setup)
                goto error;

        irq_remapping_enabled = 1;

        /*
         * VT-d has a different layout for IO-APIC entries when
         * interrupt remapping is enabled. So it needs a special routine
         * to print IO-APIC entries for debugging purposes too.
         */
        x86_io_apic_ops.print_entries = intel_ir_io_apic_print_entries;

        pr_info("Enabled IRQ remapping in %s mode\n", eim ? "x2apic" : "xapic");

        return eim ? IRQ_REMAP_X2APIC_MODE : IRQ_REMAP_XAPIC_MODE;

error:
        for_each_iommu(iommu, drhd)
                if (ecap_ir_support(iommu->ecap)) {
                        iommu_disable_irq_remapping(iommu);
                        intel_teardown_irq_remapping(iommu);
                }

        if (x2apic_present)
                pr_warn("Failed to enable irq remapping.  You are vulnerable to irq-injection attacks.\n");

        return -1;
}

static int ir_parse_one_hpet_scope(struct acpi_dmar_device_scope *scope,
                                   struct intel_iommu *iommu,
                                   struct acpi_dmar_hardware_unit *drhd)
{
        struct acpi_dmar_pci_path *path;
        u8 bus;
        int count, free = -1;

        bus = scope->bus;
        path = (struct acpi_dmar_pci_path *)(scope + 1);
        count = (scope->length - sizeof(struct acpi_dmar_device_scope))
                / sizeof(struct acpi_dmar_pci_path);

        while (--count > 0) {
                /*
                 * Access PCI directly due to the PCI
                 * subsystem isn't initialized yet.
                 */
                bus = read_pci_config_byte(bus, path->device, path->function,
                                           PCI_SECONDARY_BUS);
                path++;
        }

        for (count = 0; count < MAX_HPET_TBS; count++) {
                if (ir_hpet[count].iommu == iommu &&
                    ir_hpet[count].id == scope->enumeration_id)
                        return 0;
                else if (ir_hpet[count].iommu == NULL && free == -1)
                        free = count;
        }
        if (free == -1) {
                pr_warn("Exceeded Max HPET blocks\n");
                return -ENOSPC;
        }

        ir_hpet[free].iommu = iommu;
        ir_hpet[free].id    = scope->enumeration_id;
        ir_hpet[free].bus   = bus;
        ir_hpet[free].devfn = PCI_DEVFN(path->device, path->function);
        pr_info("HPET id %d under DRHD base 0x%Lx\n",
                scope->enumeration_id, drhd->address);

        return 0;
}

static int ir_parse_one_ioapic_scope(struct acpi_dmar_device_scope *scope,
                                     struct intel_iommu *iommu,
                                     struct acpi_dmar_hardware_unit *drhd)
{
        struct acpi_dmar_pci_path *path;
        u8 bus;
        int count, free = -1;

        bus = scope->bus;
        path = (struct acpi_dmar_pci_path *)(scope + 1);
        count = (scope->length - sizeof(struct acpi_dmar_device_scope))
                / sizeof(struct acpi_dmar_pci_path);

        while (--count > 0) {
                /*
                 * Access PCI directly due to the PCI
                 * subsystem isn't initialized yet.
                 */
                bus = read_pci_config_byte(bus, path->device, path->function,
                                           PCI_SECONDARY_BUS);
                path++;
        }

        for (count = 0; count < MAX_IO_APICS; count++) {
                if (ir_ioapic[count].iommu == iommu &&
                    ir_ioapic[count].id == scope->enumeration_id)
                        return 0;
                else if (ir_ioapic[count].iommu == NULL && free == -1)
                        free = count;
        }
        if (free == -1) {
                pr_warn("Exceeded Max IO APICS\n");
                return -ENOSPC;
        }

        ir_ioapic[free].bus   = bus;
        ir_ioapic[free].devfn = PCI_DEVFN(path->device, path->function);
        ir_ioapic[free].iommu = iommu;
        ir_ioapic[free].id    = scope->enumeration_id;
        pr_info("IOAPIC id %d under DRHD base  0x%Lx IOMMU %d\n",
                scope->enumeration_id, drhd->address, iommu->seq_id);

        return 0;
}

static int ir_parse_ioapic_hpet_scope(struct acpi_dmar_header *header,
                                      struct intel_iommu *iommu)
{
        int ret = 0;
        struct acpi_dmar_hardware_unit *drhd;
        struct acpi_dmar_device_scope *scope;
        void *start, *end;

        drhd = (struct acpi_dmar_hardware_unit *)header;
        start = (void *)(drhd + 1);
        end = ((void *)drhd) + header->length;

        while (start < end && ret == 0) {
                scope = start;
                if (scope->entry_type == ACPI_DMAR_SCOPE_TYPE_IOAPIC)
                        ret = ir_parse_one_ioapic_scope(scope, iommu, drhd);
                else if (scope->entry_type == ACPI_DMAR_SCOPE_TYPE_HPET)
                        ret = ir_parse_one_hpet_scope(scope, iommu, drhd);
                start += scope->length;
        }

        return ret;
}

static void ir_remove_ioapic_hpet_scope(struct intel_iommu *iommu)
{
        int i;

        for (i = 0; i < MAX_HPET_TBS; i++)
                if (ir_hpet[i].iommu == iommu)
                        ir_hpet[i].iommu = NULL;

        for (i = 0; i < MAX_IO_APICS; i++)
                if (ir_ioapic[i].iommu == iommu)
                        ir_ioapic[i].iommu = NULL;
}

/*
 * Finds the assocaition between IOAPIC's and its Interrupt-remapping
 * hardware unit.
 */
static int __init parse_ioapics_under_ir(void)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;
        int ir_supported = 0;
        int ioapic_idx;

        for_each_iommu(iommu, drhd)
                if (ecap_ir_support(iommu->ecap)) {
                        if (ir_parse_ioapic_hpet_scope(drhd->hdr, iommu))
                                return -1;

                        ir_supported = 1;
                }

        if (!ir_supported)
                return 0;

        for (ioapic_idx = 0; ioapic_idx < nr_ioapics; ioapic_idx++) {
                int ioapic_id = mpc_ioapic_id(ioapic_idx);
                if (!map_ioapic_to_ir(ioapic_id)) {
                        pr_err(FW_BUG "ioapic %d has no mapping iommu, "
                               "interrupt remapping will be disabled\n",
                               ioapic_id);
                        return -1;
                }
        }

        return 1;
}

static int __init ir_dev_scope_init(void)
{
        int ret;

        if (!irq_remapping_enabled)
                return 0;

        down_write(&dmar_global_lock);
        ret = dmar_dev_scope_init();
        up_write(&dmar_global_lock);

        return ret;
}
rootfs_initcall(ir_dev_scope_init);

static void disable_irq_remapping(void)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu = NULL;

        /*
         * Disable Interrupt-remapping for all the DRHD's now.
         */
        for_each_iommu(iommu, drhd) {
                if (!ecap_ir_support(iommu->ecap))
                        continue;

                iommu_disable_irq_remapping(iommu);
        }
}

static int reenable_irq_remapping(int eim)
{
        struct dmar_drhd_unit *drhd;
        int setup = 0;
        struct intel_iommu *iommu = NULL;

        for_each_iommu(iommu, drhd)
                if (iommu->qi)
                        dmar_reenable_qi(iommu);

        /*
         * Setup Interrupt-remapping for all the DRHD's now.
         */
        for_each_iommu(iommu, drhd) {
                if (!ecap_ir_support(iommu->ecap))
                        continue;

                /* Set up interrupt remapping for iommu.*/
                iommu_set_irq_remapping(iommu, eim);
                setup = 1;
        }

        if (!setup)
                goto error;

        return 0;

error:
        /*
         * handle error condition gracefully here!
         */
        return -1;
}

static void prepare_irte(struct irte *irte, int vector,
                         unsigned int dest)
{
        memset(irte, 0, sizeof(*irte));

        irte->present = 1;
        irte->dst_mode = apic->irq_dest_mode;
        /*
         * Trigger mode in the IRTE will always be edge, and for IO-APIC, the
         * actual level or edge trigger will be setup in the IO-APIC
         * RTE. This will help simplify level triggered irq migration.
         * For more details, see the comments (in io_apic.c) explainig IO-APIC
         * irq migration in the presence of interrupt-remapping.
        */
        irte->trigger_mode = 0;
        irte->dlvry_mode = apic->irq_delivery_mode;
        irte->vector = vector;
        irte->dest_id = IRTE_DEST(dest);
        irte->redir_hint = 1;
}

static int intel_setup_ioapic_entry(int irq,
                                    struct IO_APIC_route_entry *route_entry,
                                    unsigned int destination, int vector,
                                    struct io_apic_irq_attr *attr)
{
        int ioapic_id = mpc_ioapic_id(attr->ioapic);
        struct intel_iommu *iommu;
        struct IR_IO_APIC_route_entry *entry;
        struct irte irte;
        int index;

        down_read(&dmar_global_lock);
        iommu = map_ioapic_to_ir(ioapic_id);
        if (!iommu) {
                pr_warn("No mapping iommu for ioapic %d\n", ioapic_id);
                index = -ENODEV;
        } else {
                index = alloc_irte(iommu, irq, 1);
                if (index < 0) {
                        pr_warn("Failed to allocate IRTE for ioapic %d\n",
                                ioapic_id);
                        index = -ENOMEM;
                }
        }
        up_read(&dmar_global_lock);
        if (index < 0)
                return index;

        prepare_irte(&irte, vector, destination);

        /* Set source-id of interrupt request */
        set_ioapic_sid(&irte, ioapic_id);

        modify_irte(irq, &irte);

        apic_printk(APIC_VERBOSE, KERN_DEBUG "IOAPIC[%d]: "

                "Set IRTE entry (P:%d FPD:%d Dst_Mode:%d "
                "Redir_hint:%d Trig_Mode:%d Dlvry_Mode:%X "
                "Avail:%X Vector:%02X Dest:%08X "
                "SID:%04X SQ:%X SVT:%X)\n",
                attr->ioapic, irte.present, irte.fpd, irte.dst_mode,
                irte.redir_hint, irte.trigger_mode, irte.dlvry_mode,
                irte.avail, irte.vector, irte.dest_id,
                irte.sid, irte.sq, irte.svt);

        entry = (struct IR_IO_APIC_route_entry *)route_entry;
        memset(entry, 0, sizeof(*entry));

        entry->index2   = (index >> 15) & 0x1;
        entry->zero     = 0;
        entry->format   = 1;
        entry->index    = (index & 0x7fff);
        /*
         * IO-APIC RTE will be configured with virtual vector.
         * irq handler will do the explicit EOI to the io-apic.
         */
        entry->vector   = attr->ioapic_pin;
        entry->mask     = 0;                    /* enable IRQ */
        entry->trigger  = attr->trigger;
        entry->polarity = attr->polarity;

        /* Mask level triggered irqs.
         * Use IRQ_DELAYED_DISABLE for edge triggered irqs.
         */
        if (attr->trigger)
                entry->mask = 1;

        return 0;
}

/*
 * Migrate the IO-APIC irq in the presence of intr-remapping.
 *
 * For both level and edge triggered, irq migration is a simple atomic
 * update(of vector and cpu destination) of IRTE and flush the hardware cache.
 *
 * For level triggered, we eliminate the io-apic RTE modification (with the
 * updated vector information), by using a virtual vector (io-apic pin number).
 * Real vector that is used for interrupting cpu will be coming from
 * the interrupt-remapping table entry.
 *
 * As the migration is a simple atomic update of IRTE, the same mechanism
 * is used to migrate MSI irq's in the presence of interrupt-remapping.
 */
static int
intel_ioapic_set_affinity(struct irq_data *data, const struct cpumask *mask,
                          bool force)
{
        struct irq_cfg *cfg = irqd_cfg(data);
        unsigned int dest, irq = data->irq;
        struct irte irte;
        int err;

        if (!config_enabled(CONFIG_SMP))
                return -EINVAL;

        if (!cpumask_intersects(mask, cpu_online_mask))
                return -EINVAL;

        if (get_irte(irq, &irte))
                return -EBUSY;

        err = assign_irq_vector(irq, cfg, mask);
        if (err)
                return err;

        err = apic->cpu_mask_to_apicid_and(cfg->domain, mask, &dest);
        if (err) {
                if (assign_irq_vector(irq, cfg, data->affinity))
                        pr_err("Failed to recover vector for irq %d\n", irq);
                return err;
        }

        irte.vector = cfg->vector;
        irte.dest_id = IRTE_DEST(dest);

        /*
         * Atomically updates the IRTE with the new destination, vector
         * and flushes the interrupt entry cache.
         */
        modify_irte(irq, &irte);

        /*
         * After this point, all the interrupts will start arriving
         * at the new destination. So, time to cleanup the previous
         * vector allocation.
         */
        if (cfg->move_in_progress)
                send_cleanup_vector(cfg);

        cpumask_copy(data->affinity, mask);
        return 0;
}

static void intel_compose_msi_msg(struct pci_dev *pdev,
                                  unsigned int irq, unsigned int dest,
                                  struct msi_msg *msg, u8 hpet_id)
{
        struct irq_cfg *cfg;
        struct irte irte;
        u16 sub_handle = 0;
        int ir_index;

        cfg = irq_cfg(irq);

        ir_index = map_irq_to_irte_handle(irq, &sub_handle);
        BUG_ON(ir_index == -1);

        prepare_irte(&irte, cfg->vector, dest);

        /* Set source-id of interrupt request */
        if (pdev)
                set_msi_sid(&irte, pdev);
        else
                set_hpet_sid(&irte, hpet_id);

        modify_irte(irq, &irte);

        msg->address_hi = MSI_ADDR_BASE_HI;
        msg->data = sub_handle;
        msg->address_lo = MSI_ADDR_BASE_LO | MSI_ADDR_IR_EXT_INT |
                          MSI_ADDR_IR_SHV |
                          MSI_ADDR_IR_INDEX1(ir_index) |
                          MSI_ADDR_IR_INDEX2(ir_index);
}

/*
 * Map the PCI dev to the corresponding remapping hardware unit
 * and allocate 'nvec' consecutive interrupt-remapping table entries
 * in it.
 */
static int intel_msi_alloc_irq(struct pci_dev *dev, int irq, int nvec)
{
        struct intel_iommu *iommu;
        int index;

        down_read(&dmar_global_lock);
        iommu = map_dev_to_ir(dev);
        if (!iommu) {
                printk(KERN_ERR
                       "Unable to map PCI %s to iommu\n", pci_name(dev));
                index = -ENOENT;
        } else {
                index = alloc_irte(iommu, irq, nvec);
                if (index < 0) {
                        printk(KERN_ERR
                               "Unable to allocate %d IRTE for PCI %s\n",
                               nvec, pci_name(dev));
                        index = -ENOSPC;
                }
        }
        up_read(&dmar_global_lock);

        return index;
}

static int intel_msi_setup_irq(struct pci_dev *pdev, unsigned int irq,
                               int index, int sub_handle)
{
        struct intel_iommu *iommu;
        int ret = -ENOENT;

        down_read(&dmar_global_lock);
        iommu = map_dev_to_ir(pdev);
        if (iommu) {
                /*
                 * setup the mapping between the irq and the IRTE
                 * base index, the sub_handle pointing to the
                 * appropriate interrupt remap table entry.
                 */
                set_irte_irq(irq, iommu, index, sub_handle);
                ret = 0;
        }
        up_read(&dmar_global_lock);

        return ret;
}

static int intel_alloc_hpet_msi(unsigned int irq, unsigned int id)
{
        int ret = -1;
        struct intel_iommu *iommu;
        int index;

        down_read(&dmar_global_lock);
        iommu = map_hpet_to_ir(id);
        if (iommu) {
                index = alloc_irte(iommu, irq, 1);
                if (index >= 0)
                        ret = 0;
        }
        up_read(&dmar_global_lock);

        return ret;
}

struct irq_remap_ops intel_irq_remap_ops = {
        .supported              = intel_irq_remapping_supported,
        .prepare                = dmar_table_init,
        .enable                 = intel_enable_irq_remapping,
        .disable                = disable_irq_remapping,
        .reenable               = reenable_irq_remapping,
        .enable_faulting        = enable_drhd_fault_handling,
        .setup_ioapic_entry     = intel_setup_ioapic_entry,
        .set_affinity           = intel_ioapic_set_affinity,
        .free_irq               = free_irte,
        .compose_msi_msg        = intel_compose_msi_msg,
        .msi_alloc_irq          = intel_msi_alloc_irq,
        .msi_setup_irq          = intel_msi_setup_irq,
        .alloc_hpet_msi         = intel_alloc_hpet_msi,
};

/*
 * Support of Interrupt Remapping Unit Hotplug
 */
static int dmar_ir_add(struct dmar_drhd_unit *dmaru, struct intel_iommu *iommu)
{
        int ret;
        int eim = x2apic_enabled();

        if (eim && !ecap_eim_support(iommu->ecap)) {
                pr_info("DRHD %Lx: EIM not supported by DRHD, ecap %Lx\n",
                        iommu->reg_phys, iommu->ecap);
                return -ENODEV;
        }

        if (ir_parse_ioapic_hpet_scope(dmaru->hdr, iommu)) {
                pr_warn("DRHD %Lx: failed to parse managed IOAPIC/HPET\n",
                        iommu->reg_phys);
                return -ENODEV;
        }

        /* TODO: check all IOAPICs are covered by IOMMU */

        /* Setup Interrupt-remapping now. */
        ret = intel_setup_irq_remapping(iommu);
        if (ret) {
                pr_err("DRHD %Lx: failed to allocate resource\n",
                       iommu->reg_phys);
                ir_remove_ioapic_hpet_scope(iommu);
                return ret;
        }

        if (!iommu->qi) {
                /* Clear previous faults. */
                dmar_fault(-1, iommu);
                iommu_disable_irq_remapping(iommu);
                dmar_disable_qi(iommu);
        }

        /* Enable queued invalidation */
        ret = dmar_enable_qi(iommu);
        if (!ret) {
                iommu_set_irq_remapping(iommu, eim);
        } else {
                pr_err("DRHD %Lx: failed to enable queued invalidation, ecap %Lx, ret %d\n",
                       iommu->reg_phys, iommu->ecap, ret);
                intel_teardown_irq_remapping(iommu);
                ir_remove_ioapic_hpet_scope(iommu);
        }

        return ret;
}

int dmar_ir_hotplug(struct dmar_drhd_unit *dmaru, bool insert)
{
        int ret = 0;
        struct intel_iommu *iommu = dmaru->iommu;

        if (!irq_remapping_enabled)
                return 0;
        if (iommu == NULL)
                return -EINVAL;
        if (!ecap_ir_support(iommu->ecap))
                return 0;

        if (insert) {
                if (!iommu->ir_table)
                        ret = dmar_ir_add(dmaru, iommu);
        } else {
                if (iommu->ir_table) {
                        if (!bitmap_empty(iommu->ir_table->bitmap,
                                          INTR_REMAP_TABLE_ENTRIES)) {
                                ret = -EBUSY;
                        } else {
                                iommu_disable_irq_remapping(iommu);
                                intel_teardown_irq_remapping(iommu);
                                ir_remove_ioapic_hpet_scope(iommu);
                        }
                }
        }

        return ret;
}