[PATCH 1/2] kvm: unmap pages from the iommu when slots are removed

[Alex Williamson <alex.williamson@redhat.com>]

We've been adding new mappings, but not destroying old mappings.

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

 include/linux/kvm_host.h |    6 ++++++
 virt/kvm/iommu.c         |    7 ++++++-
 virt/kvm/kvm_main.c      |    5 +++--
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 900c763..bc21720 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -593,6 +593,7 @@ void kvm_free_irq_source_id(struct kvm *kvm, int irq_source_id);
 
 #ifdef CONFIG_IOMMU_API
 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,
@@ -606,6 +607,11 @@ 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 a457d21..fec1723 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 a91f980..c4ac57e 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -873,12 +873,13 @@ skip_lpage:
 	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),