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vIOMMU support works already with RamDiscardManager as long as guests only map populated memory. Both, populated and discarded memory is mapped into &address_space_memory, where vfio_get_xlat_addr() will find that memory, to create the vfio mapping. Sane guests will never map discarded memory (e.g., unplugged memory blocks in virtio-mem) into an IOMMU - or keep it mapped into an IOMMU while memory is getting discarded. However, there are two cases where a malicious guests could trigger pinning of more memory than intended. One case is easy to handle: the guest trying to map discarded memory into an IOMMU. The other case is harder to handle: the guest keeping memory mapped in the IOMMU while it is getting discarded. We would have to walk over all mappings when discarding memory and identify if any mapping would be a violation. Let's keep it simple for now and print a warning, indicating that setting RLIMIT_MEMLOCK can mitigate such attacks. We have to take care of incoming migration: at the point the IOMMUs get restored and start creating mappings in vfio, RamDiscardManager implementations might not be back up and running yet: let's add runstate priorities to enforce the order when restoring. Acked-by: Alex Williamson <alex.williamson@redhat.com> Reviewed-by: Alex Williamson <alex.williamson@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Alex Williamson <alex.williamson@redhat.com> Cc: Dr. David Alan Gilbert <dgilbert@redhat.com> Cc: Igor Mammedov <imammedo@redhat.com> Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> Cc: Peter Xu <peterx@redhat.com> Cc: Auger Eric <eric.auger@redhat.com> Cc: Wei Yang <richard.weiyang@linux.alibaba.com> Cc: teawater <teawaterz@linux.alibaba.com> Cc: Marek Kedzierski <mkedzier@redhat.com> Signed-off-by: David Hildenbrand <david@redhat.com> Message-Id: <20210413095531.25603-10-david@redhat.com> Signed-off-by: Eduardo Habkost <ehabkost@redhat.com> |
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| blocker.h | ||
| colo.h | ||
| cpu.h | ||
| failover.h | ||
| global_state.h | ||
| misc.h | ||
| qemu-file-types.h | ||
| register.h | ||
| snapshot.h | ||
| vmstate.h | ||