On 1/4/23 7:05 AM, Niklas Schnelle wrote: > On s390 when using a paging hypervisor, .iotlb_sync_map is used to sync > mappings by letting the hypervisor inspect the synced IOVA range and > updating a shadow table. This however means that .iotlb_sync_map can > fail as the hypervisor may run out of resources while doing the sync. > This can be due to the hypervisor being unable to pin guest pages, due > to a limit on mapped addresses such as vfio_iommu_type1.dma_entry_limit > or lack of other resources. Either way such a failure to sync a mapping > should result in a DMA_MAPPING_ERROR. > > Now especially when running with batched IOTLB flushes for unmap it may > be that some IOVAs have already been invalidated but not yet synced via > .iotlb_sync_map. Thus if the hypervisor indicates running out of > resources, first do a global flush allowing the hypervisor to free > resources associated with these mappings as well a retry creating the > new mappings and only if that also fails report this error to callers. > > Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx> Reviewed-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
