• Jason Wang's avatar
    vhost: log dirty page correctly · cc5e7107
    Jason Wang authored
    Vhost dirty page logging API is designed to sync through GPA. But we
    try to log GIOVA when device IOTLB is enabled. This is wrong and may
    lead to missing data after migration.
    To solve this issue, when logging with device IOTLB enabled, we will:
    1) reuse the device IOTLB translation result of GIOVA->HVA mapping to
       get HVA, for writable descriptor, get HVA through iovec. For used
       ring update, translate its GIOVA to HVA
    2) traverse the GPA->HVA mapping to get the possible GPA and log
       through GPA. Pay attention this reverse mapping is not guaranteed
       to be unique, so we should log each possible GPA in this case.
    This fix the failure of scp to guest during migration. In -next, we
    will probably support passing GIOVA->GPA instead of GIOVA->HVA.
    Fixes: 6b1e6cc7
     ("vhost: new device IOTLB API")
    Reported-by: default avatarJintack Lim <jintack@cs.columbia.edu>
    Cc: Jintack Lim <jintack@cs.columbia.edu>
    Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
    Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>