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3ea61129fe
commit 3d32e4dbe71374a6780eaf51d719d76f9a9bf22f upstream. The third parameter of kvm_unpin_pages() when called from kvm_iommu_map_pages() is wrong, it should be the number of pages to un-pin and not the page size. This error was facilitated with an inconsistent API: kvm_pin_pages() takes a size, but kvn_unpin_pages() takes a number of pages, so fix the problem by matching the two. This was introduced by commit 350b8bd ("kvm: iommu: fix the third parameter of kvm_iommu_put_pages (CVE-2014-3601)"), which fixes the lack of un-pinning for pages intended to be un-pinned (i.e. memory leak) but unfortunately potentially aggravated the number of pages we un-pin that should have stayed pinned. As far as I understand though, the same practical mitigations apply. This issue was found during review of Red Hat 6.6 patches to prepare Ksplice rebootless updates. Thanks to Vegard for his time on a late Friday evening to help me in understanding this code. Fixes: 350b8bd ("kvm: iommu: fix the third parameter of... (CVE-2014-3601)") Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com> Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Signed-off-by: Jamie Iles <jamie.iles@oracle.com> Reviewed-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
362 lines
8.5 KiB
C
362 lines
8.5 KiB
C
/*
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* Copyright (c) 2006, Intel Corporation.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 59 Temple
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* Place - Suite 330, Boston, MA 02111-1307 USA.
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*
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* Copyright (C) 2006-2008 Intel Corporation
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* Copyright IBM Corporation, 2008
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* Copyright 2010 Red Hat, Inc. and/or its affiliates.
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*
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* Author: Allen M. Kay <allen.m.kay@intel.com>
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* Author: Weidong Han <weidong.han@intel.com>
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* Author: Ben-Ami Yassour <benami@il.ibm.com>
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*/
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#include <linux/list.h>
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#include <linux/kvm_host.h>
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#include <linux/module.h>
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#include <linux/pci.h>
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#include <linux/stat.h>
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#include <linux/dmar.h>
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#include <linux/iommu.h>
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#include <linux/intel-iommu.h>
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static bool allow_unsafe_assigned_interrupts;
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module_param_named(allow_unsafe_assigned_interrupts,
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allow_unsafe_assigned_interrupts, bool, S_IRUGO | S_IWUSR);
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MODULE_PARM_DESC(allow_unsafe_assigned_interrupts,
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"Enable device assignment on platforms without interrupt remapping support.");
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static int kvm_iommu_unmap_memslots(struct kvm *kvm);
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static void kvm_iommu_put_pages(struct kvm *kvm,
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gfn_t base_gfn, unsigned long npages);
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static pfn_t kvm_pin_pages(struct kvm_memory_slot *slot, gfn_t gfn,
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unsigned long npages)
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{
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gfn_t end_gfn;
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pfn_t pfn;
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pfn = gfn_to_pfn_memslot(slot, gfn);
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end_gfn = gfn + npages;
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gfn += 1;
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if (is_error_noslot_pfn(pfn))
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return pfn;
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while (gfn < end_gfn)
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gfn_to_pfn_memslot(slot, gfn++);
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return pfn;
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}
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static void kvm_unpin_pages(struct kvm *kvm, pfn_t pfn, unsigned long npages)
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{
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unsigned long i;
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for (i = 0; i < npages; ++i)
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kvm_release_pfn_clean(pfn + i);
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}
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int kvm_iommu_map_pages(struct kvm *kvm, struct kvm_memory_slot *slot)
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{
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gfn_t gfn, end_gfn;
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pfn_t pfn;
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int r = 0;
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struct iommu_domain *domain = kvm->arch.iommu_domain;
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int flags;
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/* check if iommu exists and in use */
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if (!domain)
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return 0;
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gfn = slot->base_gfn;
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end_gfn = gfn + slot->npages;
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flags = IOMMU_READ;
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if (!(slot->flags & KVM_MEM_READONLY))
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flags |= IOMMU_WRITE;
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if (kvm->arch.iommu_flags & KVM_IOMMU_CACHE_COHERENCY)
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flags |= IOMMU_CACHE;
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while (gfn < end_gfn) {
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unsigned long page_size;
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/* Check if already mapped */
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if (iommu_iova_to_phys(domain, gfn_to_gpa(gfn))) {
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gfn += 1;
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continue;
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}
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/* Get the page size we could use to map */
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page_size = kvm_host_page_size(kvm, gfn);
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/* Make sure the page_size does not exceed the memslot */
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while ((gfn + (page_size >> PAGE_SHIFT)) > end_gfn)
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page_size >>= 1;
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/* Make sure gfn is aligned to the page size we want to map */
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while ((gfn << PAGE_SHIFT) & (page_size - 1))
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page_size >>= 1;
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/* Make sure hva is aligned to the page size we want to map */
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while (__gfn_to_hva_memslot(slot, gfn) & (page_size - 1))
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page_size >>= 1;
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/*
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* Pin all pages we are about to map in memory. This is
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* important because we unmap and unpin in 4kb steps later.
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*/
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pfn = kvm_pin_pages(slot, gfn, page_size >> PAGE_SHIFT);
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if (is_error_noslot_pfn(pfn)) {
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gfn += 1;
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continue;
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}
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/* Map into IO address space */
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r = iommu_map(domain, gfn_to_gpa(gfn), pfn_to_hpa(pfn),
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page_size, flags);
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if (r) {
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printk(KERN_ERR "kvm_iommu_map_address:"
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"iommu failed to map pfn=%llx\n", pfn);
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kvm_unpin_pages(kvm, pfn, page_size >> PAGE_SHIFT);
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goto unmap_pages;
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}
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gfn += page_size >> PAGE_SHIFT;
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}
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return 0;
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unmap_pages:
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kvm_iommu_put_pages(kvm, slot->base_gfn, gfn - slot->base_gfn);
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return r;
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}
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static int kvm_iommu_map_memslots(struct kvm *kvm)
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{
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int idx, r = 0;
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struct kvm_memslots *slots;
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struct kvm_memory_slot *memslot;
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idx = srcu_read_lock(&kvm->srcu);
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slots = kvm_memslots(kvm);
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kvm_for_each_memslot(memslot, slots) {
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r = kvm_iommu_map_pages(kvm, memslot);
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if (r)
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break;
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}
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srcu_read_unlock(&kvm->srcu, idx);
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return r;
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}
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int kvm_assign_device(struct kvm *kvm,
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struct kvm_assigned_dev_kernel *assigned_dev)
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{
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struct pci_dev *pdev = NULL;
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struct iommu_domain *domain = kvm->arch.iommu_domain;
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int r, last_flags;
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/* check if iommu exists and in use */
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if (!domain)
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return 0;
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pdev = assigned_dev->dev;
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if (pdev == NULL)
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return -ENODEV;
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r = iommu_attach_device(domain, &pdev->dev);
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if (r) {
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dev_err(&pdev->dev, "kvm assign device failed ret %d", r);
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return r;
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}
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last_flags = kvm->arch.iommu_flags;
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if (iommu_domain_has_cap(kvm->arch.iommu_domain,
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IOMMU_CAP_CACHE_COHERENCY))
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kvm->arch.iommu_flags |= KVM_IOMMU_CACHE_COHERENCY;
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/* Check if need to update IOMMU page table for guest memory */
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if ((last_flags ^ kvm->arch.iommu_flags) ==
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KVM_IOMMU_CACHE_COHERENCY) {
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kvm_iommu_unmap_memslots(kvm);
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r = kvm_iommu_map_memslots(kvm);
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if (r)
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goto out_unmap;
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}
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pdev->dev_flags |= PCI_DEV_FLAGS_ASSIGNED;
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printk(KERN_DEBUG "assign device %x:%x:%x.%x\n",
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assigned_dev->host_segnr,
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assigned_dev->host_busnr,
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PCI_SLOT(assigned_dev->host_devfn),
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PCI_FUNC(assigned_dev->host_devfn));
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return 0;
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out_unmap:
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kvm_iommu_unmap_memslots(kvm);
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return r;
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}
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int kvm_deassign_device(struct kvm *kvm,
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struct kvm_assigned_dev_kernel *assigned_dev)
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{
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struct iommu_domain *domain = kvm->arch.iommu_domain;
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struct pci_dev *pdev = NULL;
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/* check if iommu exists and in use */
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if (!domain)
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return 0;
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pdev = assigned_dev->dev;
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if (pdev == NULL)
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return -ENODEV;
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iommu_detach_device(domain, &pdev->dev);
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pdev->dev_flags &= ~PCI_DEV_FLAGS_ASSIGNED;
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printk(KERN_DEBUG "deassign device %x:%x:%x.%x\n",
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assigned_dev->host_segnr,
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assigned_dev->host_busnr,
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PCI_SLOT(assigned_dev->host_devfn),
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PCI_FUNC(assigned_dev->host_devfn));
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return 0;
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}
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int kvm_iommu_map_guest(struct kvm *kvm)
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{
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int r;
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if (!iommu_present(&pci_bus_type)) {
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printk(KERN_ERR "%s: iommu not found\n", __func__);
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return -ENODEV;
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}
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mutex_lock(&kvm->slots_lock);
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kvm->arch.iommu_domain = iommu_domain_alloc(&pci_bus_type);
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if (!kvm->arch.iommu_domain) {
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r = -ENOMEM;
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goto out_unlock;
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}
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if (!allow_unsafe_assigned_interrupts &&
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!iommu_domain_has_cap(kvm->arch.iommu_domain,
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IOMMU_CAP_INTR_REMAP)) {
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printk(KERN_WARNING "%s: No interrupt remapping support,"
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" disallowing device assignment."
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" Re-enble with \"allow_unsafe_assigned_interrupts=1\""
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" module option.\n", __func__);
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iommu_domain_free(kvm->arch.iommu_domain);
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kvm->arch.iommu_domain = NULL;
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r = -EPERM;
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goto out_unlock;
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}
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r = kvm_iommu_map_memslots(kvm);
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if (r)
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kvm_iommu_unmap_memslots(kvm);
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out_unlock:
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mutex_unlock(&kvm->slots_lock);
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return r;
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}
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static void kvm_iommu_put_pages(struct kvm *kvm,
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gfn_t base_gfn, unsigned long npages)
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{
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struct iommu_domain *domain;
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gfn_t end_gfn, gfn;
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pfn_t pfn;
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u64 phys;
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domain = kvm->arch.iommu_domain;
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end_gfn = base_gfn + npages;
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gfn = base_gfn;
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/* check if iommu exists and in use */
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if (!domain)
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return;
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while (gfn < end_gfn) {
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unsigned long unmap_pages;
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size_t size;
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/* Get physical address */
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phys = iommu_iova_to_phys(domain, gfn_to_gpa(gfn));
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if (!phys) {
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gfn++;
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continue;
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}
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pfn = phys >> PAGE_SHIFT;
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/* Unmap address from IO address space */
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size = iommu_unmap(domain, gfn_to_gpa(gfn), PAGE_SIZE);
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unmap_pages = 1ULL << get_order(size);
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/* Unpin all pages we just unmapped to not leak any memory */
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kvm_unpin_pages(kvm, pfn, unmap_pages);
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gfn += unmap_pages;
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}
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}
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void kvm_iommu_unmap_pages(struct kvm *kvm, struct kvm_memory_slot *slot)
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{
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kvm_iommu_put_pages(kvm, slot->base_gfn, slot->npages);
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}
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static int kvm_iommu_unmap_memslots(struct kvm *kvm)
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{
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int idx;
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struct kvm_memslots *slots;
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struct kvm_memory_slot *memslot;
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idx = srcu_read_lock(&kvm->srcu);
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slots = kvm_memslots(kvm);
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kvm_for_each_memslot(memslot, slots)
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kvm_iommu_unmap_pages(kvm, memslot);
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srcu_read_unlock(&kvm->srcu, idx);
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return 0;
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}
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int kvm_iommu_unmap_guest(struct kvm *kvm)
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{
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struct iommu_domain *domain = kvm->arch.iommu_domain;
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/* check if iommu exists and in use */
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if (!domain)
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return 0;
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mutex_lock(&kvm->slots_lock);
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kvm_iommu_unmap_memslots(kvm);
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kvm->arch.iommu_domain = NULL;
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mutex_unlock(&kvm->slots_lock);
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iommu_domain_free(domain);
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return 0;
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}
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