kvm: Obey read-only mappings in iommu

We've been ignoring read-only mappings and programming everything
into the iommu as read-write.  Fix this to only include the write
access flag when read-only is not set.

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index 4a340cb..72a130b 100644 (file)
--- a/virt/kvm/iommu.c
+++ b/virt/kvm/iommu.c
@@ -76,7 +76,9 @@ int kvm_iommu_map_pages(struct kvm *kvm, struct kvm_memory_slot *slot)
        gfn     = slot->base_gfn;
        end_gfn = gfn + slot->npages;
 
-       flags = IOMMU_READ | IOMMU_WRITE;
+       flags = IOMMU_READ;
+       if (!(slot->flags & KVM_MEM_READONLY))
+               flags |= IOMMU_WRITE;
        if (kvm->arch.iommu_flags & KVM_IOMMU_CACHE_COHERENCY)
                flags |= IOMMU_CACHE;