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>

1 files changed, 3 insertions, 1 deletions

diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index 4a340cb23013..72a130bc448a 100644
--- 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;