lguest: use eventfds for device notification

Currently, when a Guest wants to perform I/O it calls LHCALL_NOTIFY with
an address: the main Launcher process returns with this address, and figures
out what device to run.

A far nicer model is to let processes bind an eventfd to an address: if we
find one, we simply signal the eventfd.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Davide Libenzi <davidel@xmailserver.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/lguest_launcher.h b/include/linux/lguest_launcher.h
index a53407a4165c..9de964b90586 100644
--- a/include/linux/lguest_launcher.h
+++ b/include/linux/lguest_launcher.h
@@ -58,6 +58,7 @@ enum lguest_req
         LHREQ_GETDMA, /* No longer used */
         LHREQ_IRQ, /* + irq */
         LHREQ_BREAK, /* + on/off flag (on blocks until someone does off) */
+        LHREQ_EVENTFD, /* + address, fd. */
 };
 
 /* The alignment to use between consumer and producer parts of vring.