Lguest guests are UP, but the host is probably SMP, so real barriers are
required in case the device thread and the guest are on different CPUs.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

The virtio spec was missing a barrier in example code, so I went back
to look at the lguest code.  Indeed, we need one.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

After commit 07fe9977, lguest tool has already moved from
Documentation/virtual/lguest/ to tools/lguest/.
Signed-off-by: NWanlong Gao <gaowanlong@cn.fujitsu.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

The CONFIG_EXPERIMENTAL config item has not carried much meaning for a
while now and is almost always enabled by default. As agreed during the
Linux kernel summit, remove it from any "depends on" lines in Kconfigs.

CC: Rusty Russell <rusty@rustcorp.com.au>
CC: Davidlohr Bueso <dave@gnu.org>
Signed-off-by: NKees Cook <keescook@chromium.org>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>

virtio requests are scatter-gather-style descriptors, but no
assumptions should be made about the layout.  lguest was lazy here,
but saved by the fact that the network device hands all requests to
tun (which does it correctly) and console and random devices simply
use readv and writev.

Block devices, however, are broken: we convert to iovecs internally,
just make sure we handle the correctly.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

We usually got away with ->next on the final entry being NULL, but it
finally bit me.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Cc: stable@kernel.org

This is a better location instead of having it in Documentation.
Signed-off-by: NDavidlohr Bueso <dave@gnu.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (fixed compile)