KVM: Device Assignment with VT-d

Based on a patch by: Kay, Allen M <allen.m.kay@intel.com>

This patch enables PCI device assignment based on VT-d support.
When a device is assigned to the guest, the guest memory is pinned and
the mapping is updated in the VT-d IOMMU.

[Amit: Expose KVM_CAP_IOMMU so we can check if an IOMMU is present
and also control enable/disable from userspace]

Signed-off-by: Kay, Allen M <allen.m.kay@intel.com>
Signed-off-by: Weidong Han <weidong.han@intel.com>
Signed-off-by: Ben-Ami Yassour <benami@il.ibm.com>
Signed-off-by: Amit Shah <amit.shah@qumranet.com>

Acked-by: Mark Gross <mgross@linux.intel.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

3 files changed, 215 insertions, 0 deletions

diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index d0e940bb6f40..3072b17447ab 100644
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile
@@ -12,6 +12,9 @@ EXTRA_CFLAGS += -Ivirt/kvm -Iarch/x86/kvm
 
 kvm-objs := $(common-objs) x86.o mmu.o x86_emulate.o i8259.o irq.o lapic.o \
         i8254.o
+ifeq ($(CONFIG_DMAR),y)
+kvm-objs += vtd.o
+endif
 obj-$(CONFIG_KVM) += kvm.o
 kvm-intel-objs = vmx.o
 obj-$(CONFIG_KVM_INTEL) += kvm-intel.o
diff --git a/arch/x86/kvm/vtd.c b/arch/x86/kvm/vtd.c
new file mode 100644
index 000000000000..667bf3fb64bf
--- /dev/null
+++ b/arch/x86/kvm/vtd.c
@@ -0,0 +1,198 @@
+/*
+ * 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
+ * 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/pci.h>
+#include <linux/dmar.h>
+#include <linux/intel-iommu.h>
+
+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);
+
+int kvm_iommu_map_pages(struct kvm *kvm,
+                        gfn_t base_gfn, unsigned long npages)
+{
+        gfn_t gfn = base_gfn;
+        pfn_t pfn;
+        int i, r;
+        struct dmar_domain *domain = kvm->arch.intel_iommu_domain;
+
+        /* check if iommu exists and in use */
+        if (!domain)
+                return 0;
+
+        r = -EINVAL;
+        for (i = 0; i < npages; i++) {
+                /* check if already mapped */
+                pfn = (pfn_t)intel_iommu_iova_to_pfn(domain,
+                                                     gfn_to_gpa(gfn));
+                if (pfn && !is_mmio_pfn(pfn))
+                        continue;
+
+                pfn = gfn_to_pfn(kvm, gfn);
+                if (!is_mmio_pfn(pfn)) {
+                        r = intel_iommu_page_mapping(domain,
+                                                     gfn_to_gpa(gfn),
+                                                     pfn_to_hpa(pfn),
+                                                     PAGE_SIZE,
+                                                     DMA_PTE_READ |
+                                                     DMA_PTE_WRITE);
+                        if (r) {
+                                printk(KERN_DEBUG "kvm_iommu_map_pages:"
+                                       "iommu failed to map pfn=%lx\n", pfn);
+                                goto unmap_pages;
+                        }
+                } else {
+                        printk(KERN_DEBUG "kvm_iommu_map_page:"
+                               "invalid pfn=%lx\n", pfn);
+                        goto unmap_pages;
+                }
+                gfn++;
+        }
+        return 0;
+
+unmap_pages:
+        kvm_iommu_put_pages(kvm, base_gfn, i);
+        return r;
+}
+
+static int kvm_iommu_map_memslots(struct kvm *kvm)
+{
+        int i, r;
+
+        down_read(&kvm->slots_lock);
+        for (i = 0; i < kvm->nmemslots; i++) {
+                r = kvm_iommu_map_pages(kvm, kvm->memslots[i].base_gfn,
+                                        kvm->memslots[i].npages);
+                if (r)
+                        break;
+        }
+        up_read(&kvm->slots_lock);
+        return r;
+}
+
+int kvm_iommu_map_guest(struct kvm *kvm,
+                        struct kvm_assigned_dev_kernel *assigned_dev)
+{
+        struct pci_dev *pdev = NULL;
+        int r;
+
+        if (!intel_iommu_found()) {
+                printk(KERN_ERR "%s: intel iommu not found\n", __func__);
+                return -ENODEV;
+        }
+
+        printk(KERN_DEBUG "VT-d direct map: host bdf = %x:%x:%x\n",
+               assigned_dev->host_busnr,
+               PCI_SLOT(assigned_dev->host_devfn),
+               PCI_FUNC(assigned_dev->host_devfn));
+
+        pdev = assigned_dev->dev;
+
+        if (pdev == NULL) {
+                if (kvm->arch.intel_iommu_domain) {
+                        intel_iommu_domain_exit(kvm->arch.intel_iommu_domain);
+                        kvm->arch.intel_iommu_domain = NULL;
+                }
+                return -ENODEV;
+        }
+
+        kvm->arch.intel_iommu_domain = intel_iommu_domain_alloc(pdev);
+        if (!kvm->arch.intel_iommu_domain)
+                return -ENODEV;
+
+        r = kvm_iommu_map_memslots(kvm);
+        if (r)
+                goto out_unmap;
+
+        intel_iommu_detach_dev(kvm->arch.intel_iommu_domain,
+                               pdev->bus->number, pdev->devfn);
+
+        r = intel_iommu_context_mapping(kvm->arch.intel_iommu_domain,
+                                        pdev);
+        if (r) {
+                printk(KERN_ERR "Domain context map for %s failed",
+                       pci_name(pdev));
+                goto out_unmap;
+        }
+        return 0;
+
+out_unmap:
+        kvm_iommu_unmap_memslots(kvm);
+        return r;
+}
+
+static void kvm_iommu_put_pages(struct kvm *kvm,
+                               gfn_t base_gfn, unsigned long npages)
+{
+        gfn_t gfn = base_gfn;
+        pfn_t pfn;
+        struct dmar_domain *domain = kvm->arch.intel_iommu_domain;
+        int i;
+
+        for (i = 0; i < npages; i++) {
+                pfn = (pfn_t)intel_iommu_iova_to_pfn(domain,
+                                                     gfn_to_gpa(gfn));
+                kvm_release_pfn_clean(pfn);
+                gfn++;
+        }
+}
+
+static int kvm_iommu_unmap_memslots(struct kvm *kvm)
+{
+        int i;
+        down_read(&kvm->slots_lock);
+        for (i = 0; i < kvm->nmemslots; i++) {
+                kvm_iommu_put_pages(kvm, kvm->memslots[i].base_gfn,
+                                    kvm->memslots[i].npages);
+        }
+        up_read(&kvm->slots_lock);
+
+        return 0;
+}
+
+int kvm_iommu_unmap_guest(struct kvm *kvm)
+{
+        struct kvm_assigned_dev_kernel *entry;
+        struct dmar_domain *domain = kvm->arch.intel_iommu_domain;
+
+        /* check if iommu exists and in use */
+        if (!domain)
+                return 0;
+
+        list_for_each_entry(entry, &kvm->arch.assigned_dev_head, list) {
+                printk(KERN_DEBUG "VT-d unmap: host bdf = %x:%x:%x\n",
+                       entry->host_busnr,
+                       PCI_SLOT(entry->host_devfn),
+                       PCI_FUNC(entry->host_devfn));
+
+                /* detach kvm dmar domain */
+                intel_iommu_detach_dev(domain, entry->host_busnr,
+                                       entry->host_devfn);
+        }
+        kvm_iommu_unmap_memslots(kvm);
+        intel_iommu_domain_exit(domain);
+        return 0;
+}
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 2134f3e0a516..c8a2793626ec 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -35,6 +35,7 @@
 #include <linux/module.h>
 #include <linux/mman.h>
 #include <linux/highmem.h>
+#include <linux/intel-iommu.h>
 
 #include <asm/uaccess.h>
 #include <asm/msr.h>
@@ -277,9 +278,18 @@ static int kvm_vm_ioctl_assign_device(struct kvm *kvm,
 
         list_add(&match->list, &kvm->arch.assigned_dev_head);
 
+        if (assigned_dev->flags & KVM_DEV_ASSIGN_ENABLE_IOMMU) {
+                r = kvm_iommu_map_guest(kvm, match);
+                if (r)
+                        goto out_list_del;
+        }
+
 out:
         mutex_unlock(&kvm->lock);
         return r;
+out_list_del:
+        list_del(&match->list);
+        pci_release_regions(dev);
 out_disable:
         pci_disable_device(dev);
 out_put:
@@ -1147,6 +1157,9 @@ int kvm_dev_ioctl_check_extension(long ext)
         case KVM_CAP_PV_MMU:
                 r = !tdp_enabled;
                 break;
+        case KVM_CAP_IOMMU:
+                r = intel_iommu_found();
+                break;
         default:
                 r = 0;
                 break;
@@ -4282,6 +4295,7 @@ static void kvm_free_vcpus(struct kvm *kvm)
 
 void kvm_arch_destroy_vm(struct kvm *kvm)
 {
+        kvm_iommu_unmap_guest(kvm);
         kvm_free_assigned_devices(kvm);
         kvm_free_pit(kvm);
         kfree(kvm->arch.vpic);