KVM: IOMMU: Disable device assignment without interrupt remapping (3f68b031) · Commits · 戴 / test

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>

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;

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