Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 3f68b031 authored by Alex Williamson's avatar Alex Williamson Committed by Avi Kivity
Browse files

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: default avatarAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: default avatarMarcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 4f022648

virt/kvm/iommu.c

+18 −0
Original line number Diff line number Diff line
@@ -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;