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authorAlex Williamson <alex.williamson@redhat.com>2011-07-14 13:27:03 -0600
committerAvi Kivity <avi@redhat.com>2011-07-24 11:50:42 +0300
commit3f68b0318bbbd61bf08478ab99a149f0d9e5156e (patch)
tree5caa009c012cee6b61de36f1aa643c9443684423 /virt
parent4f0226482d20f104e943ee9e6f1218b573953f63 (diff)
downloadlinux-3f68b0318bbbd61bf08478ab99a149f0d9e5156e.tar.gz
KVM: IOMMU: Disable device assignment without interrupt remapping
IOMMU interrupt remapping support provides a further layer of isolation for device assignment by preventing arbitrary interrupt block DMA writes by a malicious guest from reaching the host. By default, we should require that the platform provides interrupt remapping support, with an opt-in mechanism for existing behavior. Both AMD IOMMU and Intel VT-d2 hardware support interrupt remapping, however we currently only have software support on the Intel side. Users wishing to re-enable device assignment when interrupt remapping is not supported on the platform can use the "allow_unsafe_assigned_interrupts=1" module option. [avi: break long lines] Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/iommu.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index 62a9caf0563..78c80f67f53 100644
--- a/virt/kvm/iommu.c
+++ b/virt/kvm/iommu.c
@@ -30,6 +30,12 @@
#include <linux/iommu.h>
#include <linux/intel-iommu.h>
+static int 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);
@@ -231,6 +237,18 @@ int kvm_iommu_map_guest(struct kvm *kvm)
if (!kvm->arch.iommu_domain)
return -ENOMEM;
+ 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;
+ return -EPERM;
+ }
+
r = kvm_iommu_map_memslots(kvm);
if (r)
goto out_unmap;