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>

1 files changed, 14 insertions, 0 deletions

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);