[PATCH 0/2] kvm: iommu cleanup

[PATCH 0/2] kvm: iommu cleanup

[Alex Williamson]

When using device assignment, new page mappings are added to the iommu,
but never removed.  Fix it.  We're also lazy about tearing down the
iommu and unpinning the guest when we have no assigned devices attached.
Instead of waiting for the vm to be destroyed, do these cleanups when
we deassign the last assigned device.  Thanks,

Alex

---

Alex Williamson (2):
      kvm: unpin guest and free iommu domain after deassign last device
      kvm: unmap pages from the iommu when slots are removed


 include/linux/kvm_host.h |    6 ++++++
 virt/kvm/assigned-dev.c  |    3 +++
 virt/kvm/iommu.c         |    8 +++++++-
 virt/kvm/kvm_main.c      |    5 +++--
 4 files changed, 19 insertions(+), 3 deletions(-)

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

[Alex Williamson]

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),

[PATCH 2/2] kvm: unpin guest and free iommu domain after deassign last device

[Alex Williamson]

Unpin the guest and free the iommu domain if there are no longer
any devices attached.

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

 virt/kvm/assigned-dev.c |    3 +++
 virt/kvm/iommu.c        |    1 +
 2 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c
index 758e3b3..9d6b31a 100644
--- a/virt/kvm/assigned-dev.c
+++ b/virt/kvm/assigned-dev.c
@@ -673,6 +673,9 @@ static int kvm_vm_ioctl_deassign_device(struct kvm *kvm,
 
 	kvm_free_assigned_device(kvm, match);
 
+	if (list_empty(&kvm->arch.assigned_dev_head))
+		kvm_iommu_unmap_guest(kvm);
+
 out:
 	mutex_unlock(&kvm->lock);
 	return r;
diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index fec1723..ee4c236 100644
--- a/virt/kvm/iommu.c
+++ b/virt/kvm/iommu.c
@@ -342,5 +342,6 @@ int kvm_iommu_unmap_guest(struct kvm *kvm)
 
 	kvm_iommu_unmap_memslots(kvm);
 	iommu_domain_free(domain);
+	kvm->arch.iommu_domain = NULL;
 	return 0;
 }