iommu.c

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/*
 * 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 <[email protected]>
 * Author: Weidong Han <[email protected]>
 * Author: Ben-Ami Yassour <[email protected]>
 */

#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;
}