/*
 * Copyright (c) 2006, Intel Corporation.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 59 Temple
 * Place - Suite 330, Boston, MA 02111-1307 USA.
 *
 * Copyright (C) 2006-2008 Intel Corporation
 * Copyright IBM Corporation, 2008
 * Copyright 2010 Red Hat, Inc. and/or its affiliates.
 *
 * Author: Allen M. Kay <allen.m.kay@intel.com>
 * Author: Weidong Han <weidong.han@intel.com>
 * Author: Ben-Ami Yassour <benami@il.ibm.com>
 */

#include <linux/list.h>
#include <linux/kvm_host.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/stat.h>
#include <linux/dmar.h>
#include <linux/iommu.h>
#include <linux/intel-iommu.h>

static bool allow_unsafe_assigned_interrupts;
module_param_named(allow_unsafe_assigned_interrupts,
                   allow_unsafe_assigned_interrupts, bool, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(allow_unsafe_assigned_interrupts,
 "Enable device assignment on platforms without interrupt remapping support.");

static int kvm_iommu_unmap_memslots(struct kvm *kvm);
static void kvm_iommu_put_pages(struct kvm *kvm,
                                gfn_t base_gfn, unsigned long npages);

static pfn_t kvm_pin_pages(struct kvm_memory_slot *slot, gfn_t gfn,
                           unsigned long size)
{
        gfn_t end_gfn;
        pfn_t pfn;

        pfn     = gfn_to_pfn_memslot(slot, gfn);
        end_gfn = gfn + (size >> PAGE_SHIFT);
        gfn    += 1;

        if (is_error_pfn(pfn))
                return pfn;

        while (gfn < end_gfn)
                gfn_to_pfn_memslot(slot, gfn++);

        return pfn;
}

int kvm_iommu_map_pages(struct kvm *kvm, struct kvm_memory_slot *slot)
{
        gfn_t gfn, end_gfn;
        pfn_t pfn;
        int r = 0;
        struct iommu_domain *domain = kvm->arch.iommu_domain;
        int flags;

        /* check if iommu exists and in use */
        if (!domain)
                return 0;

        gfn     = slot->base_gfn;
        end_gfn = gfn + slot->npages;

        flags = IOMMU_READ | IOMMU_WRITE;
        if (kvm->arch.iommu_flags & KVM_IOMMU_CACHE_COHERENCY)
                flags |= IOMMU_CACHE;


        while (gfn < end_gfn) {
                unsigned long page_size;

                /* Check if already mapped */
                if (iommu_iova_to_phys(domain, gfn_to_gpa(gfn))) {
                        gfn += 1;
                        continue;
                }

                /* Get the page size we could use to map */
                page_size = kvm_host_page_size(kvm, gfn);

                /* Make sure the page_size does not exceed the memslot */
                while ((gfn + (page_size >> PAGE_SHIFT)) > end_gfn)
                        page_size >>= 1;

                /* Make sure gfn is aligned to the page size we want to map */
                while ((gfn << PAGE_SHIFT) & (page_size - 1))
                        page_size >>= 1;

                /*
                 * Pin all pages we are about to map in memory. This is
                 * important because we unmap and unpin in 4kb steps later.
                 */
                pfn = kvm_pin_pages(slot, gfn, page_size);
                if (is_error_pfn(pfn)) {
                        gfn += 1;
                        continue;
                }

                /* Map into IO address space */
                r = iommu_map(domain, gfn_to_gpa(gfn), pfn_to_hpa(pfn),
                              page_size, flags);
                if (r) {
                        printk(KERN_ERR "kvm_iommu_map_address:"
                               "iommu failed to map pfn=%llx\n", pfn);
                        goto unmap_pages;
                }

                gfn += page_size >> PAGE_SHIFT;


        }

        return 0;

unmap_pages:
        kvm_iommu_put_pages(kvm, slot->base_gfn, gfn);
        return r;
}

static int kvm_iommu_map_memslots(struct kvm *kvm)
{
        int idx, r = 0;
        struct kvm_memslots *slots;
        struct kvm_memory_slot *memslot;

        idx = srcu_read_lock(&kvm->srcu);
        slots = kvm_memslots(kvm);

        kvm_for_each_memslot(memslot, slots) {
                r = kvm_iommu_map_pages(kvm, memslot);
                if (r)
                        break;
        }
        srcu_read_unlock(&kvm->srcu, idx);

        return r;
}

int kvm_assign_device(struct kvm *kvm,
                      struct kvm_assigned_dev_kernel *assigned_dev)
{
        struct pci_dev *pdev = NULL;
        struct iommu_domain *domain = kvm->arch.iommu_domain;
        int r, last_flags;

        /* check if iommu exists and in use */
        if (!domain)
                return 0;

        pdev = assigned_dev->dev;
        if (pdev == NULL)
                return -ENODEV;

        r = iommu_attach_device(domain, &pdev->dev);
        if (r) {
                printk(KERN_ERR "assign device %x:%x:%x.%x failed",
                        pci_domain_nr(pdev->bus),
                        pdev->bus->number,
                        PCI_SLOT(pdev->devfn),
                        PCI_FUNC(pdev->devfn));
                return r;
        }

        last_flags = kvm->arch.iommu_flags;
        if (iommu_domain_has_cap(kvm->arch.iommu_domain,
                                 IOMMU_CAP_CACHE_COHERENCY))
                kvm->arch.iommu_flags |= KVM_IOMMU_CACHE_COHERENCY;

        /* Check if need to update IOMMU page table for guest memory */
        if ((last_flags ^ kvm->arch.iommu_flags) ==
                        KVM_IOMMU_CACHE_COHERENCY) {
                kvm_iommu_unmap_memslots(kvm);
                r = kvm_iommu_map_memslots(kvm);
                if (r)
                        goto out_unmap;
        }

        pdev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED;

        printk(KERN_DEBUG "assign device %x:%x:%x.%x\n",
                assigned_dev->host_segnr,
                assigned_dev->host_busnr,
                PCI_SLOT(assigned_dev->host_devfn),
                PCI_FUNC(assigned_dev->host_devfn));

        return 0;
out_unmap:
        kvm_iommu_unmap_memslots(kvm);
        return r;
}

int kvm_deassign_device(struct kvm *kvm,
                        struct kvm_assigned_dev_kernel *assigned_dev)
{
        struct iommu_domain *domain = kvm->arch.iommu_domain;
        struct pci_dev *pdev = NULL;

        /* check if iommu exists and in use */
        if (!domain)
                return 0;

        pdev = assigned_dev->dev;
        if (pdev == NULL)
                return -ENODEV;

        iommu_detach_device(domain, &pdev->dev);

        pdev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;

        printk(KERN_DEBUG "deassign device %x:%x:%x.%x\n",
                assigned_dev->host_segnr,
                assigned_dev->host_busnr,
                PCI_SLOT(assigned_dev->host_devfn),
                PCI_FUNC(assigned_dev->host_devfn));

        return 0;
}

int kvm_iommu_map_guest(struct kvm *kvm)
{
        int r;

        if (!iommu_present(&pci_bus_type)) {
                printk(KERN_ERR "%s: iommu not found\n", __func__);
                return -ENODEV;
        }

        mutex_lock(&kvm->slots_lock);

        kvm->arch.iommu_domain = iommu_domain_alloc(&pci_bus_type);
        if (!kvm->arch.iommu_domain) {
                r = -ENOMEM;
                goto out_unlock;
        }

        if (!allow_unsafe_assigned_interrupts &&
            !iommu_domain_has_cap(kvm->arch.iommu_domain,
                                  IOMMU_CAP_INTR_REMAP)) {
                printk(KERN_WARNING "%s: No interrupt remapping support,"
                       " disallowing device assignment."
                       " Re-enble with \"allow_unsafe_assigned_interrupts=1\""
                       " module option.\n", __func__);
                iommu_domain_free(kvm->arch.iommu_domain);
                kvm->arch.iommu_domain = NULL;
                r = -EPERM;
                goto out_unlock;
        }

        r = kvm_iommu_map_memslots(kvm);
        if (r)
                kvm_iommu_unmap_memslots(kvm);

out_unlock:
        mutex_unlock(&kvm->slots_lock);
        return r;
}

static void kvm_unpin_pages(struct kvm *kvm, pfn_t pfn, unsigned long npages)
{
        unsigned long i;

        for (i = 0; i < npages; ++i)
                kvm_release_pfn_clean(pfn + i);
}

static void kvm_iommu_put_pages(struct kvm *kvm,
                                gfn_t base_gfn, unsigned long npages)
{
        struct iommu_domain *domain;
        gfn_t end_gfn, gfn;
        pfn_t pfn;
        u64 phys;

        domain  = kvm->arch.iommu_domain;
        end_gfn = base_gfn + npages;
        gfn     = base_gfn;

        /* check if iommu exists and in use */
        if (!domain)
                return;

        while (gfn < end_gfn) {
                unsigned long unmap_pages;
                size_t size;

                /* Get physical address */
                phys = iommu_iova_to_phys(domain, gfn_to_gpa(gfn));

                if (!phys) {
                        gfn++;
                        continue;
                }

                pfn  = phys >> PAGE_SHIFT;

                /* Unmap address from IO address space */
                size       = iommu_unmap(domain, gfn_to_gpa(gfn), PAGE_SIZE);
                unmap_pages = 1ULL << get_order(size);

                /* Unpin all pages we just unmapped to not leak any memory */
                kvm_unpin_pages(kvm, pfn, unmap_pages);

                gfn += unmap_pages;
        }
}

void kvm_iommu_unmap_pages(struct kvm *kvm, struct kvm_memory_slot *slot)
{
        kvm_iommu_put_pages(kvm, slot->base_gfn, slot->npages);
}

static int kvm_iommu_unmap_memslots(struct kvm *kvm)
{
        int idx;
        struct kvm_memslots *slots;
        struct kvm_memory_slot *memslot;

        idx = srcu_read_lock(&kvm->srcu);
        slots = kvm_memslots(kvm);

        kvm_for_each_memslot(memslot, slots)
                kvm_iommu_unmap_pages(kvm, memslot);

        srcu_read_unlock(&kvm->srcu, idx);

        return 0;
}

int kvm_iommu_unmap_guest(struct kvm *kvm)
{
        struct iommu_domain *domain = kvm->arch.iommu_domain;

        /* check if iommu exists and in use */
        if (!domain)
                return 0;

        mutex_lock(&kvm->slots_lock);
        kvm_iommu_unmap_memslots(kvm);
        kvm->arch.iommu_domain = NULL;
        mutex_unlock(&kvm->slots_lock);

        iommu_domain_free(domain);
        return 0;
}