// SPDX-License-Identifier: GPL-2.0

#define pr_fmt(fmt)     "DMAR-IR: " fmt

#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 <linux/irqdomain.h>
#include <linux/crash_dump.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"

enum irq_mode {
        IRQ_REMAPPING,
        IRQ_POSTING,
};

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;
};

struct irq_2_iommu {
        struct intel_iommu *iommu;
        u16 irte_index;
        u16 sub_handle;
        u8  irte_mask;
        enum irq_mode mode;
};

struct intel_ir_data {
        struct irq_2_iommu                      irq_2_iommu;
        struct irte                             irte_entry;
        union {
                struct msi_msg                  msi_entry;
        };
};

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

static int __read_mostly eim_mode;
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.
 */
DEFINE_RAW_SPINLOCK(irq_2_ir_lock);
static const struct irq_domain_ops intel_ir_domain_ops;

static void iommu_disable_irq_remapping(struct intel_iommu *iommu);
static int __init parse_ioapics_under_ir(void);

static bool ir_pre_enabled(struct intel_iommu *iommu)
{
        return (iommu->flags & VTD_FLAG_IRQ_REMAP_PRE_ENABLED);
}

static void clear_ir_pre_enabled(struct intel_iommu *iommu)
{
        iommu->flags &= ~VTD_FLAG_IRQ_REMAP_PRE_ENABLED;
}

static void init_ir_status(struct intel_iommu *iommu)
{
        u32 gsts;

        gsts = readl(iommu->reg + DMAR_GSTS_REG);
        if (gsts & DMA_GSTS_IRES)
                iommu->flags |= VTD_FLAG_IRQ_REMAP_PRE_ENABLED;
}

static int alloc_irte(struct intel_iommu *iommu,
                      struct irq_2_iommu *irq_iommu, u16 count)
{
        struct ir_table *table = iommu->ir_table;
        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)) {
                pr_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 {
                irq_iommu->iommu = iommu;
                irq_iommu->irte_index =  index;
                irq_iommu->sub_handle = 0;
                irq_iommu->irte_mask = mask;
                irq_iommu->mode = IRQ_REMAPPING;
        }
        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.qw0 = QI_IEC_IIDEX(index) | QI_IEC_TYPE | QI_IEC_IM(mask)
                   | QI_IEC_SELECTIVE;
        desc.qw1 = 0;
        desc.qw2 = 0;
        desc.qw3 = 0;

        return qi_submit_sync(&desc, iommu);
}

static int modify_irte(struct irq_2_iommu *irq_iommu,
                       struct irte *irte_modified)
{
        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];

#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE)
        if ((irte->pst == 1) || (irte_modified->pst == 1)) {
                bool ret;

                ret = cmpxchg_double(&irte->low, &irte->high,
                                     irte->low, irte->high,
                                     irte_modified->low, irte_modified->high);
                /*
                 * We use cmpxchg16 to atomically update the 128-bit IRTE,
                 * and it cannot be updated by the hardware or other processors
                 * behind us, so the return value of cmpxchg16 should be the
                 * same as the old value.
                 */
                WARN_ON(!ret);
        } else
#endif
        {
                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);

        /* Update iommu mode according to the IRTE mode */
        irq_iommu->mode = irte->pst ? IRQ_POSTING : IRQ_REMAPPING;
        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;

        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);
}

/*
 * 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;
}

/*
 * Set an IRTE to match only the bus number. Interrupt requests that reference
 * this IRTE must have a requester-id whose bus number is between or equal
 * to the start_bus and end_bus arguments.
 */
static void set_irte_verify_bus(struct irte *irte, unsigned int start_bus,
                                unsigned int end_bus)
{
        set_irte_sid(irte, SVT_VERIFY_BUS, SQ_ALL_16,
                     (start_bus << 8) | end_bus);
}

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_warn("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_warn("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;
        int count;
        int busmatch_count;
};

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;
        data->count++;

        if (PCI_BUS_NUM(alias) == pdev->bus->number)
                data->busmatch_count++;

        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;

        data.count = 0;
        data.busmatch_count = 0;
        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 there are multiple aliases, all with the same bus number,
         * then all we can do is verify the bus. This is typical in NTB
         * hardware which use proxy IDs where the device will generate traffic
         * from multiple devfn numbers on the same 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_verify_bus(irte, PCI_BUS_NUM(data.alias),
                                    dev->bus->number);
        else if (data.count >= 2 && data.busmatch_count == data.count)
                set_irte_verify_bus(irte, dev->bus->number, 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_dev_id(dev));

        return 0;
}

static int iommu_load_old_irte(struct intel_iommu *iommu)
{
        struct irte *old_ir_table;
        phys_addr_t irt_phys;
        unsigned int i;
        size_t size;
        u64 irta;

        /* Check whether the old ir-table has the same size as ours */
        irta = dmar_readq(iommu->reg + DMAR_IRTA_REG);
        if ((irta & INTR_REMAP_TABLE_REG_SIZE_MASK)
             != INTR_REMAP_TABLE_REG_SIZE)
                return -EINVAL;

        irt_phys = irta & VTD_PAGE_MASK;
        size     = INTR_REMAP_TABLE_ENTRIES*sizeof(struct irte);

        /* Map the old IR table */
        old_ir_table = memremap(irt_phys, size, MEMREMAP_WB);
        if (!old_ir_table)
                return -ENOMEM;

        /* Copy data over */
        memcpy(iommu->ir_table->base, old_ir_table, size);

        __iommu_flush_cache(iommu, iommu->ir_table->base, size);

        /*
         * Now check the table for used entries and mark those as
         * allocated in the bitmap
         */
        for (i = 0; i < INTR_REMAP_TABLE_ENTRIES; i++) {
                if (iommu->ir_table->base[i].present)
                        bitmap_set(iommu->ir_table->bitmap, i, 1);
        }

        memunmap(old_ir_table);

        return 0;
}


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

        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 to make sure the
         * hardware uses the new irq remapping table.
         */
        qi_global_iec(iommu);
}

static void iommu_enable_irq_remapping(struct intel_iommu *iommu)
{
        unsigned long flags;
        u32 sts;

        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 fwnode_handle *fn;
        unsigned long *bitmap;
        struct page *pages;

        if (iommu->ir_table)
                return 0;

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

        pages = alloc_pages_node(iommu->node, GFP_KERNEL | __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 = bitmap_zalloc(INTR_REMAP_TABLE_ENTRIES, GFP_ATOMIC);
        if (bitmap == NULL) {
                pr_err("IR%d: failed to allocate bitmap\n", iommu->seq_id);
                goto out_free_pages;
        }

        fn = irq_domain_alloc_named_id_fwnode("INTEL-IR", iommu->seq_id);
        if (!fn)
                goto out_free_bitmap;

        iommu->ir_domain =
                irq_domain_create_hierarchy(arch_get_ir_parent_domain(),
                                            0, INTR_REMAP_TABLE_ENTRIES,
                                            fn, &intel_ir_domain_ops,
                                            iommu);
        irq_domain_free_fwnode(fn);
        if (!iommu->ir_domain) {
                pr_err("IR%d: failed to allocate irqdomain\n", iommu->seq_id);
                goto out_free_bitmap;
        }
        iommu->ir_msi_domain =
                arch_create_remap_msi_irq_domain(iommu->ir_domain,
                                                 "INTEL-IR-MSI",
                                                 iommu->seq_id);

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

        /*
         * If the queued invalidation is already initialized,
         * shouldn't disable it.
         */
        if (!iommu->qi) {
                /*
                 * Clear previous faults.
                 */
                dmar_fault(-1, iommu);
                dmar_disable_qi(iommu);

                if (dmar_enable_qi(iommu)) {
                        pr_err("Failed to enable queued invalidation\n");
                        goto out_free_bitmap;
                }
        }

        init_ir_status(iommu);

        if (ir_pre_enabled(iommu)) {
                if (!is_kdump_kernel()) {
                        pr_warn("IRQ remapping was enabled on %s but we are not in kdump mode\n",
                                iommu->name);
                        clear_ir_pre_enabled(iommu);
                        iommu_disable_irq_remapping(iommu);
                } else if (iommu_load_old_irte(iommu))
                        pr_err("Failed to copy IR table for %s from previous kernel\n",
                               iommu->name);
                else
                        pr_info("Copied IR table for %s from previous kernel\n",
                                iommu->name);
        }

        iommu_set_irq_remapping(iommu, eim_mode);

        return 0;

out_free_bitmap:
        bitmap_free(bitmap);
out_free_pages:
        __free_pages(pages, INTR_REMAP_PAGE_ORDER);
out_free_table:
        kfree(ir_table);

        iommu->ir_table  = NULL;

        return -ENOMEM;
}

static void intel_teardown_irq_remapping(struct intel_iommu *iommu)
{
        if (iommu && iommu->ir_table) {
                if (iommu->ir_msi_domain) {
                        irq_domain_remove(iommu->ir_msi_domain);
                        iommu->ir_msi_domain = NULL;
                }
                if (iommu->ir_domain) {
                        irq_domain_remove(iommu->ir_domain);
                        iommu->ir_domain = NULL;
                }
                free_pages((unsigned long)iommu->ir_table->base,
                           INTR_REMAP_PAGE_ORDER);
                bitmap_free(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 = readl(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 void __init intel_cleanup_irq_remapping(void)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;

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

        if (x2apic_supported())
                pr_warn("Failed to enable irq remapping. You are vulnerable to irq-injection attacks.\n");
}

static int __init intel_prepare_irq_remapping(void)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;
        int eim = 0;

        if (irq_remap_broken) {
                pr_warn("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);
                return -ENODEV;
        }

        if (dmar_table_init() < 0)
                return -ENODEV;

        if (!dmar_ir_support())
                return -ENODEV;

        if (parse_ioapics_under_ir()) {
                pr_info("Not enabling interrupt remapping\n");
                goto error;
        }

        /* First make sure all IOMMUs support IRQ remapping */
        for_each_iommu(iommu, drhd)
                if (!ecap_ir_support(iommu->ecap))
                        goto error;

        /* Detect remapping mode: lapic or x2apic */
        if (x2apic_supported()) {
                eim = !dmar_x2apic_optout();
                if (!eim) {
                        pr_info("x2apic is disabled because BIOS sets x2apic opt out bit.");
                        pr_info("Use 'intremap=no_x2apic_optout' to override the BIOS setting.\n");
                }
        }

        for_each_iommu(iommu, drhd) {
                if (eim && !ecap_eim_support(iommu->ecap)) {
                        pr_info("%s does not support EIM\n", iommu->name);
                        eim = 0;
                }
        }

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

        /* Do the initializations early */
        for_each_iommu(iommu, drhd) {
                if (intel_setup_irq_remapping(iommu)) {
                        pr_err("Failed to setup irq remapping for %s\n",
                               iommu->name);
                        goto error;
                }
        }

        return 0;

error:
        intel_cleanup_irq_remapping();
        return -ENODEV;
}

/*
 * Set Posted-Interrupts capability.
 */
static inline void set_irq_posting_cap(void)
{
        struct dmar_drhd_unit *drhd;
        struct intel_iommu *iommu;

        if (!disable_irq_post) {
                /*
                 * If IRTE is in posted format, the 'pda' field goes across the
                 * 64-bit boundary, we need use cmpxchg16b to atomically update
                 * it. We only expose posted-interrupt when X86_FEATURE_CX16
                 * is supported. Actually, hardware platforms supporting PI
                 * should have X86_FEATURE_CX16 support, this has been confirmed
                 * with Intel hardware guys.
                 */
                if (boot_cpu_has(X86_FEATURE_CX16))
                        intel_irq_remap_ops.capability |= 1 << IRQ_POSTING_CAP;

                for_each_iommu(iommu, drhd)
                        if (!cap_pi_support(iommu->cap)) {
                                intel_irq_remap_ops.capability &=
                                                ~(1 << IRQ_POSTING_CAP);
                                break;
                        }
        }
}

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

        /*
         * Setup Interrupt-remapping for all the DRHD's now.
         */
        for_each_iommu(iommu, drhd) {
                if (!ir_pre_enabled(iommu))
                        iommu_enable_irq_remapping(iommu);
                setup = true;
        }

        if (!setup)
                goto error;

        irq_remapping_enabled = 1;

        set_irq_posting_cap();

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

        return eim_mode ? IRQ_REMAP_X2APIC_MODE : IRQ_REMAP_XAPIC_MODE;

error:
        intel_cleanup_irq_remapping();
        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;
        bool ir_supported = false;
        int ioapic_idx;

        for_each_iommu(iommu, drhd) {
                int ret;

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

                ret = ir_parse_ioapic_hpet_scope(drhd->hdr, iommu);
                if (ret)
                        return ret;

                ir_supported = true;
        }

        if (!ir_supported)
                return -ENODEV;

        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 0;
}

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);
        }

        /*
         * Clear Posted-Interrupts capability.
         */
        if (!disable_irq_post)
                intel_irq_remap_ops.capability &= ~(1 << IRQ_POSTING_CAP);
}

static int reenable_irq_remapping(int eim)
{
        struct dmar_drhd_unit *drhd;
        bool setup = false;
        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);
                iommu_enable_irq_remapping(iommu);
                setup = true;
        }

        if (!setup)
                goto error;

        set_irq_posting_cap();

        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 struct irq_domain *intel_get_ir_irq_domain(struct irq_alloc_info *info)
{
        struct intel_iommu *iommu = NULL;

        if (!info)
                return NULL;

        switch (info->type) {
        case X86_IRQ_ALLOC_TYPE_IOAPIC:
                iommu = map_ioapic_to_ir(info->ioapic_id);
                break;
        case X86_IRQ_ALLOC_TYPE_HPET:
                iommu = map_hpet_to_ir(info->hpet_id);
                break;
        case X86_IRQ_ALLOC_TYPE_MSI:
        case X86_IRQ_ALLOC_TYPE_MSIX:
                iommu = map_dev_to_ir(info->msi_dev);
                break;
        default:
                BUG_ON(1);
                break;
        }

        return iommu ? iommu->ir_domain : NULL;
}

static struct irq_domain *intel_get_irq_domain(struct irq_alloc_info *info)
{
        struct intel_iommu *iommu;

        if (!info)
                return NULL;

        switch (info->type) {
        case X86_IRQ_ALLOC_TYPE_MSI:
        case X86_IRQ_ALLOC_TYPE_MSIX:
                iommu = map_dev_to_ir(info->msi_dev);
                if (iommu)
                        return iommu->ir_msi_domain;
                break;
        default:
                break;
        }

        return NULL;
}

struct irq_remap_ops intel_irq_remap_ops = {
        .prepare                = intel_prepare_irq_remapping,
        .enable                 = intel_enable_irq_remapping,
        .disable                = disable_irq_remapping,
        .reenable               = reenable_irq_remapping,
        .enable_faulting        = enable_drhd_fault_handling,
        .get_ir_irq_domain      = intel_get_ir_irq_domain,
        .get_irq_domain         = intel_get_irq_domain,
};

static void intel_ir_reconfigure_irte(struct irq_data *irqd, bool force)
{
        struct intel_ir_data *ir_data = irqd->chip_data;
        struct irte *irte = &ir_data->irte_entry;
        struct irq_cfg *cfg = irqd_cfg(irqd);

        /*
         * Atomically updates the IRTE with the new destination, vector
         * and flushes the interrupt entry cache.
         */
        irte->vector = cfg->vector;
        irte->dest_id = IRTE_DEST(cfg->dest_apicid);

        /* Update the hardware only if the interrupt is in remapped mode. */
        if (force || ir_data->irq_2_iommu.mode == IRQ_REMAPPING)
                modify_irte(&ir_data->irq_2_iommu, irte);
}

/*
 * 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_ir_set_affinity(struct irq_data *data, const struct cpumask *mask,
                      bool force)
{
        struct irq_data *parent = data->parent_data;
        struct irq_cfg *cfg = irqd_cfg(data);
        int ret;

        ret = parent->chip->irq_set_affinity(parent, mask, force);
        if (ret < 0 || ret == IRQ_SET_MASK_OK_DONE)
                return ret;

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

        return IRQ_SET_MASK_OK_DONE;
}

static void intel_ir_compose_msi_msg(struct irq_data *irq_data,
                                     struct msi_msg *msg)
{
        struct intel_ir_data *ir_data = irq_data->chip_data;

        *msg = ir_data->msi_entry;
}

static int intel_ir_set_vcpu_affinity(struct irq_data *data, void *info)
{
        struct intel_ir_data *ir_data = data->chip_data;
        struct vcpu_data *vcpu_pi_info = info;

        /* stop posting interrupts, back to remapping mode */
        if (!vcpu_pi_info) {
                modify_irte(&ir_data->irq_2_iommu, &ir_data->irte_entry);
        } else {
                struct irte irte_pi;

                /*
                 * We are not caching the posted interrupt entry. We
                 * copy the data from the remapped entry and modify
                 * the fields which are relevant for posted mode. The
                 * cached remapped entry is used for switching back to
                 * remapped mode.
                 */
                memset(&irte_pi, 0, sizeof(irte_pi));
                dmar_copy_shared_irte(&irte_pi, &ir_data->irte_entry);

                /* Update the posted mode fields */
                irte_pi.p_pst = 1;
                irte_pi.p_urgent = 0;
                irte_pi.p_vector = vcpu_pi_info->vector;
                irte_pi.pda_l = (vcpu_pi_info->pi_desc_addr >>
                                (32 - PDA_LOW_BIT)) & ~(-1UL << PDA_LOW_BIT);
                irte_pi.pda_h = (vcpu_pi_info->pi_desc_addr >> 32) &
                                ~(-1UL << PDA_HIGH_BIT);

                modify_irte(&ir_data->irq_2_iommu, &irte_pi);
        }

        return 0;
}

static struct irq_chip intel_ir_chip = {
        .name                   = "INTEL-IR",
        .irq_ack                = apic_ack_irq,
        .irq_set_affinity       = intel_ir_set_affinity,
        .irq_compose_msi_msg    = intel_ir_compose_msi_msg,
        .irq_set_vcpu_affinity  = intel_ir_set_vcpu_affinity,
};

static void intel_irq_remapping_prepare_irte(struct intel_ir_data *data,
                                             struct irq_cfg *irq_cfg,
                                             struct irq_alloc_info *info,
                                             int index, int sub_handle)
{
        struct IR_IO_APIC_route_entry *entry;
        struct irte *irte = &data->irte_entry;
        struct msi_msg *msg = &data->msi_entry;

        prepare_irte(irte, irq_cfg->vector, irq_cfg->dest_apicid);
        switch (info->type) {
        case X86_IRQ_ALLOC_TYPE_IOAPIC:
                /* Set source-id of interrupt request */
                set_ioapic_sid(irte, info->ioapic_id);
                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",
                        info->ioapic_id, 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 *)info->ioapic_entry;
                info->ioapic_entry = NULL;
                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   = info->ioapic_pin;
                entry->mask     = 0;                    /* enable IRQ */
                entry->trigger  = info->ioapic_trigger;
                entry->polarity = info->ioapic_polarity;
                if (info->ioapic_trigger)
                        entry->mask = 1; /* Mask level triggered irqs. */
                break;

        case X86_IRQ_ALLOC_TYPE_HPET:
        case X86_IRQ_ALLOC_TYPE_MSI:
        case X86_IRQ_ALLOC_TYPE_MSIX:
                if (info->type == X86_IRQ_ALLOC_TYPE_HPET)
                        set_hpet_sid(irte, info->hpet_id);
                else
                        set_msi_sid(irte, info->msi_dev);

                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(index) |
                                  MSI_ADDR_IR_INDEX2(index);
                break;

        default:
                BUG_ON(1);
                break;
        }
}

static void intel_free_irq_resources(struct irq_domain *domain,
                                     unsigned int virq, unsigned int nr_irqs)
{
        struct irq_data *irq_data;
        struct intel_ir_data *data;
        struct irq_2_iommu *irq_iommu;
        unsigned long flags;
        int i;
        for (i = 0; i < nr_irqs; i++) {
                irq_data = irq_domain_get_irq_data(domain, virq  + i);
                if (irq_data && irq_data->chip_data) {
                        data = irq_data->chip_data;
                        irq_iommu = &data->irq_2_iommu;
                        raw_spin_lock_irqsave(&irq_2_ir_lock, flags);
                        clear_entries(irq_iommu);
                        raw_spin_unlock_irqrestore(&irq_2_ir_lock, flags);
                        irq_domain_reset_irq_data(irq_data);
                        kfree(data);
                }
        }
}

static int intel_irq_remapping_alloc(struct irq_domain *domain,
                                     unsigned int virq, unsigned int nr_irqs,
                                     void *arg)
{
        struct intel_iommu *iommu = domain->host_data;
        struct irq_alloc_info *info = arg;
        struct intel_ir_data *data, *ird;
        struct irq_data *irq_data;
        struct irq_cfg *irq_cfg;
        int i, ret, index;

        if (!info || !iommu)
                return -EINVAL;
        if (nr_irqs > 1 && info->type != X86_IRQ_ALLOC_TYPE_MSI &&
            info->type != X86_IRQ_ALLOC_TYPE_MSIX)
                return -EINVAL;

        /*
         * With IRQ remapping enabled, don't need contiguous CPU vectors
         * to support multiple MSI interrupts.
         */
        if (info->type == X86_IRQ_ALLOC_TYPE_MSI)
                info->flags &= ~X86_IRQ_ALLOC_CONTIGUOUS_VECTORS;

        ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, arg);
        if (ret < 0)
                return ret;

        ret = -ENOMEM;
        data = kzalloc(sizeof(*data), GFP_KERNEL);
        if (!data)
                goto out_free_parent;

        down_read(&dmar_global_lock);
        index = alloc_irte(iommu, &data->irq_2_iommu, nr_irqs);
        up_read(&dmar_global_lock);
        if (index < 0) {
                pr_warn("Failed to allocate IRTE\n");
                kfree(data);
                goto out_free_parent;
        }

        for (i = 0; i < nr_irqs; i++) {
                irq_data = irq_domain_get_irq_data(domain, virq + i);
                irq_cfg = irqd_cfg(irq_data);
                if (!irq_data || !irq_cfg) {
                        ret = -EINVAL;
                        goto out_free_data;
                }

                if (i > 0) {
                        ird = kzalloc(sizeof(*ird), GFP_KERNEL);
                        if (!ird)
                                goto out_free_data;
                        /* Initialize the common data */
                        ird->irq_2_iommu = data->irq_2_iommu;
                        ird->irq_2_iommu.sub_handle = i;
                } else {
                        ird = data;
                }

                irq_data->hwirq = (index << 16) + i;
                irq_data->chip_data = ird;
                irq_data->chip = &intel_ir_chip;
                intel_irq_remapping_prepare_irte(ird, irq_cfg, info, index, i);
                irq_set_status_flags(virq + i, IRQ_MOVE_PCNTXT);
        }
        return 0;

out_free_data:
        intel_free_irq_resources(domain, virq, i);
out_free_parent:
        irq_domain_free_irqs_common(domain, virq, nr_irqs);
        return ret;
}

static void intel_irq_remapping_free(struct irq_domain *domain,
                                     unsigned int virq, unsigned int nr_irqs)
{
        intel_free_irq_resources(domain, virq, nr_irqs);
        irq_domain_free_irqs_common(domain, virq, nr_irqs);
}

static int intel_irq_remapping_activate(struct irq_domain *domain,
                                        struct irq_data *irq_data, bool reserve)
{
        intel_ir_reconfigure_irte(irq_data, true);
        return 0;
}

static void intel_irq_remapping_deactivate(struct irq_domain *domain,
                                           struct irq_data *irq_data)
{
        struct intel_ir_data *data = irq_data->chip_data;
        struct irte entry;

        memset(&entry, 0, sizeof(entry));
        modify_irte(&data->irq_2_iommu, &entry);
}

static const struct irq_domain_ops intel_ir_domain_ops = {
        .alloc = intel_irq_remapping_alloc,
        .free = intel_irq_remapping_free,
        .activate = intel_irq_remapping_activate,
        .deactivate = intel_irq_remapping_deactivate,
};

/*
 * 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("Failed to setup irq remapping for %s\n",
                       iommu->name);
                intel_teardown_irq_remapping(iommu);
                ir_remove_ioapic_hpet_scope(iommu);
        } else {
                iommu_enable_irq_remapping(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 (irq_remapping_cap(IRQ_POSTING_CAP) &&
            !cap_pi_support(iommu->cap))
                return -EBUSY;

        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;
}