At present the memory listener used by vfio to keep host IOMMU mappings
in sync with the guest memory image assumes that if a guest IOMMU
appears, then it has no existing mappings.
This may not be true if a VFIO device is hotplugged onto a guest bus
which didn't previously include a VFIO device, and which has existing
guest IOMMU mappings.
Therefore, use the memory_region_register_iommu_notifier_replay()
function in order to fix this case, replaying existing guest IOMMU
mappings, bringing the host IOMMU into sync with the guest IOMMU.
Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
---
hw/vfio/common.c | 34 +++++++++++++++++++---------------
1 file changed, 19 insertions(+), 15 deletions(-)
diff --git a/hw/vfio/common.c b/hw/vfio/common.c
index daaac48..543c38e 100644
--- a/hw/vfio/common.c
+++ b/hw/vfio/common.c
@@ -312,6 +312,22 @@ out:
rcu_read_unlock();
}
+static hwaddr vfio_container_granularity(VFIOContainer *container)
+{
+ uint64_t pgsize;
+
+ assert(container->iommu_data.iova_pgsizes);
+
+ /* Find the smallest page size supported by the IOMMU */
+ for (pgsize = 1; pgsize; pgsize <<= 1) {
+ if (pgsize & container->iommu_data.iova_pgsizes) {
+ return pgsize;
+ }
+ }
+ /* Can't happen */
+ assert(0);
+}
+
static void vfio_listener_region_add(MemoryListener *listener,
MemoryRegionSection *section)
{
@@ -371,26 +387,14 @@ static void vfio_listener_region_add(MemoryListener
*listener,
* would be the right place to wire that up (tell the KVM
* device emulation the VFIO iommu handles to use).
*/
- /*
- * This assumes that the guest IOMMU is empty of
- * mappings at this point.
- *
- * One way of doing this is:
- * 1. Avoid sharing IOMMUs between emulated devices or different
- * IOMMU groups.
- * 2. Implement VFIO_IOMMU_ENABLE in the host kernel to fail if
- * there are some mappings in IOMMU.
- *
- * VFIO on SPAPR does that. Other IOMMU models may do that different,
- * they must make sure there are no existing mappings or
- * loop through existing mappings to map them into VFIO.
- */
giommu = g_malloc0(sizeof(*giommu));
giommu->iommu = section->mr;
giommu->container = container;
giommu->n.notify = vfio_iommu_map_notify;
QLIST_INSERT_HEAD(&container->giommu_list, giommu, giommu_next);
- memory_region_register_iommu_notifier(giommu->iommu, &giommu->n);
+
+ memory_region_register_iommu_notifier_replay(giommu->iommu, &giommu->n,
+ vfio_container_granularity(container), false);
return;
}
--
2.4.3
