qemu/include
Stefan Hajnoczi fcccb271e0 virtio: notify virtqueue via host notifier when available
Host notifiers are used in several cases:
1. Traditional ioeventfd where virtqueue notifications are handled in
   the main loop thread.
2. IOThreads (aio_handle_output) where virtqueue notifications are
   handled in an IOThread AioContext.
3. vhost where virtqueue notifications are handled by kernel vhost or
   a vhost-user device backend.

Most virtqueue notifications from the guest use the ioeventfd mechanism,
but there are corner cases where QEMU code calls virtio_queue_notify().
This currently honors the host notifier for the IOThreads
aio_handle_output case, but not for the vhost case.  The result is that
vhost does not receive virtqueue notifications from QEMU when
virtio_queue_notify() is called.

This patch extends virtio_queue_notify() to set the host notifier
whenever it is enabled instead of calling the vq->(aio_)handle_output()
function directly.  We track the host notifier state for each virtqueue
separately since some devices may use it only for certain virtqueues.

This fixes the vhost case although it does add a trip through the
eventfd for the traditional ioeventfd case.  I don't think it's worth
adding a fast path for the traditional ioeventfd case because calling
virtio_queue_notify() is rare when ioeventfd is enabled.

Reported-by: Felipe Franciosi <felipe@nutanix.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20191105140946.165584-1-stefanha@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2019-11-06 06:35:00 -05:00
..
authz Include generated QAPI headers less 2019-08-16 13:31:51 +02:00
block block: Add @exact parameter to bdrv_co_truncate() 2019-10-28 12:00:07 +01:00
chardev Include qemu/main-loop.h less 2019-08-16 13:31:52 +02:00
crypto crypto: define cleanup functions for use with g_autoptr 2019-08-22 10:47:12 +01:00
disas plugin: add qemu_plugin_insn_disas helper 2019-10-28 15:12:38 +00:00
exec TCG Plugins initial implementation 2019-10-30 14:10:32 +00:00
fpu fpu: make softfloat-macros "self-contained" 2019-08-19 12:07:13 +01:00
hw virtio: notify virtqueue via host notifier when available 2019-11-06 06:35:00 -05:00
io socket: Add num connections to qio_net_listener_open_sync() 2019-09-03 23:24:42 +02:00
libdecnumber include: Make headers more self-contained 2019-08-16 13:31:51 +02:00
migration migration: add new migration state wait-unplug 2019-10-29 18:55:26 -04:00
monitor Include hw/qdev-properties.h less 2019-08-16 13:31:53 +02:00
net Include qemu/queue.h slightly less 2019-08-16 13:31:52 +02:00
qapi qapi: Make visit_next_list()'s comment less confusing 2019-09-24 11:03:44 +02:00
qemu target/arm/cpu64: max cpu: Introduce sve<N> properties 2019-11-01 20:40:59 +00:00
qom vl: Split off user_creatable_print_help() 2019-10-14 17:12:48 +02:00
scsi scsi: explicitly list guest-recoverable sense codes 2019-07-15 11:20:42 +02:00
standard-headers linux headers: update against v5.4-rc1 2019-10-15 18:09:02 +01:00
sysemu bootdevice: FW_CFG interface for LCHS values 2019-10-31 11:47:38 -04:00
ui ui/egl: fix framebuffer reads 2019-09-17 13:42:02 +02:00
user *-user: plugin syscalls 2019-10-28 15:12:38 +00:00
elf.h linux-user: elf: ELF_HWCAP for s390x 2019-06-07 14:53:26 +02:00
glib-compat.h glib: bump min required glib library version to 2.48 2019-08-22 10:46:34 +01:00
qemu-common.h exec: Split out variable page size support to exec-vary.c 2019-10-28 10:26:02 +01:00
qemu-io.h Include qemu-common.h exactly where needed 2019-06-12 13:20:20 +02:00
trace-tcg.h