From 8a08b9c7379dc881ff5f00c086877353888a982f Mon Sep 17 00:00:00 2001 From: Cornelia Huck Date: Tue, 26 Jan 2016 10:48:59 +0100 Subject: [PATCH] KVM: s390: usage hint for adapter mappings The interface for adapter mappings was designed with code in mind that maps each address only once; let's document this. Otherwise, duplicate mappings are added to the list, which makes the code ineffective and uses up the limited amount of mapping needlessly. Signed-off-by: Cornelia Huck Signed-off-by: Christian Borntraeger --- Documentation/virtual/kvm/devices/s390_flic.txt | 2 ++ 1 file changed, 2 insertions(+) diff --git a/Documentation/virtual/kvm/devices/s390_flic.txt b/Documentation/virtual/kvm/devices/s390_flic.txt index d1ad9d5cae46..e3e314cb83e8 100644 --- a/Documentation/virtual/kvm/devices/s390_flic.txt +++ b/Documentation/virtual/kvm/devices/s390_flic.txt @@ -88,6 +88,8 @@ struct kvm_s390_io_adapter_req { perform a gmap translation for the guest address provided in addr, pin a userspace page for the translated address and add it to the list of mappings + Note: A new mapping will be created unconditionally; therefore, + the calling code should avoid making duplicate mappings. KVM_S390_IO_ADAPTER_UNMAP release a userspace page for the translated address specified in addr -- 2.20.1