diff options
authorAlex Williamson <alex.williamson@redhat.com>2012-04-11 09:51:49 -0600
committerMarcelo Tosatti <mtosatti@redhat.com>2012-04-11 22:55:25 -0300
commit32f6daad4651a748a58a3ab6da0611862175722f (patch)
parentf19a0c2c2e6add90b7d6a1b7595abebfe2e4c37a (diff)
KVM: unmap pages from the iommu when slots are removed
We've been adding new mappings, but not destroying old mappings. This can lead to a page leak as pages are pinned using get_user_pages, but only unpinned with put_page if they still exist in the memslots list on vm shutdown. A memslot that is destroyed while an iommu domain is enabled for the guest will therefore result in an elevated page reference count that is never cleared. Additionally, without this fix, the iommu is only programmed with the first translation for a gpa. This can result in peer-to-peer errors if a mapping is destroyed and replaced by a new mapping at the same gpa as the iommu will still be pointing to the original, pinned memory address. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
3 files changed, 15 insertions, 3 deletions
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 665a260c7e0..72cbf08d45f 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -596,6 +596,7 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id);
int kvm_iommu_map_pages(struct kvm *kvm, struct kvm_memory_slot *slot);
+void kvm_iommu_unmap_pages(struct kvm *kvm, struct kvm_memory_slot *slot);
int kvm_iommu_map_guest(struct kvm *kvm);
int kvm_iommu_unmap_guest(struct kvm *kvm);
int kvm_assign_device(struct kvm *kvm,
@@ -609,6 +610,11 @@ static inline int kvm_iommu_map_pages(struct kvm *kvm,
return 0;
+static inline void kvm_iommu_unmap_pages(struct kvm *kvm,
+ struct kvm_memory_slot *slot)
static inline int kvm_iommu_map_guest(struct kvm *kvm)
return -ENODEV;
diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index a457d2138f4..fec1723de9b 100644
--- a/virt/kvm/iommu.c
+++ b/virt/kvm/iommu.c
@@ -310,6 +310,11 @@ static void kvm_iommu_put_pages(struct kvm *kvm,
+void kvm_iommu_unmap_pages(struct kvm *kvm, struct kvm_memory_slot *slot)
+ kvm_iommu_put_pages(kvm, slot->base_gfn, slot->npages);
static int kvm_iommu_unmap_memslots(struct kvm *kvm)
int idx;
@@ -320,7 +325,7 @@ static int kvm_iommu_unmap_memslots(struct kvm *kvm)
slots = kvm_memslots(kvm);
kvm_for_each_memslot(memslot, slots)
- kvm_iommu_put_pages(kvm, memslot->base_gfn, memslot->npages);
+ kvm_iommu_unmap_pages(kvm, memslot);
srcu_read_unlock(&kvm->srcu, idx);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 42b73930a6d..9739b533ca2 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -808,12 +808,13 @@ int __kvm_set_memory_region(struct kvm *kvm,
if (r)
goto out_free;
- /* map the pages in iommu page table */
+ /* map/unmap the pages in iommu page table */
if (npages) {
r = kvm_iommu_map_pages(kvm, &new);
if (r)
goto out_free;
- }
+ } else
+ kvm_iommu_unmap_pages(kvm, &old);
r = -ENOMEM;
slots = kmemdup(kvm->memslots, sizeof(struct kvm_memslots),