Add a pseudo RTC that simply is able to send an alarm signal
waking up the system at a given time in the future.

Since apparently timerfd_create() FDs don't support SIGIO, we
use the sigio-creating helper thread, which just learned to do
suspend/resume properly in the previous patch.

For time-travel mode, OTOH, just add an event at the specified
time in the future, and that's already sufficient to wake up
the system at that point in time since suspend will just be in
an "endless wait".

For s2idle support also call pm_system_wakeup().

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

There is a spelling mistake in the Kconfig help text. Fix it.

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

With all the IRQ machinery being in place, we can allow virtio
devices to additionally be configured as wakeup sources, in
which case basically any interrupt from them wakes us up. Note
that this requires a call FD because the VQs are all disabled.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

In external time-travel mode, where time is controlled via the
controller application socket, interrupt handling is a little
tricky. For example on virtio, the following happens:
 * we receive a message (that requires an ACK) on the vhost-user socket
 * we add a time-travel event to handle the interrupt
   (this causes communication on the time socket)
 * we ACK the original vhost-user message
 * we then handle the interrupt once the event is triggered

This protocol ensures that the sender of the interrupt only continues
to run in the simulation when the time-travel event has been added.

So far, this was only done in the virtio driver, but it was actually
wrong, because only virtqueue interrupts were handled this way, and
config change interrupts were handled immediately. Additionally, the
messages were actually handled in the real Linux interrupt handler,
but Linux interrupt handlers are part of the simulation and shouldn't
run while there's no time event.

To really do this properly and only handle all kinds of interrupts in
the time-travel event when we are scheduled to run in the simulation,
rework this to plug in to the lower interrupt layers in UML directly:

Add a um_request_irq_tt() function that let's a time-travel aware
driver request an interrupt with an additional timetravel_handler()
that is called outside of the context of the simulation, to handle
the message only. It then adds an event to the time-travel calendar
if necessary, and no "real" Linux code runs outside of the time
simulation.

This also hooks in with suspend/resume properly now, since this new
timetravel_handler() can run while Linux is suspended and interrupts
are disabled, and decide to wake up (or not) the system based on the
message it received. Importantly in this case, it ACKs the message
before the system even resumes and interrupts are re-enabled, thus
allowing the simulation to progress properly.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

If the system is suspended, the device shouldn't be able to send
anything to it. Disable virtqueues in suspend to simulate this,
and as we might be only using s2idle (kernel services are still
on), prevent sending anything on them as well.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

If we have a message without payload, we call full_read() with
len set to 0, which causes it to return -ECONNRESET. Catch this
case and explicitly return 0 for it so we can actually use the
zero-size config-changed message.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

There's no 'simtime' device, because implementing that through
virtio was just too much complexity. Clean up the comment that
still refers to it.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

This reverts commit ef4459a6da09 ("um: allocate a guard page to
helper threads"), it's broken in multiple ways:

 1) the free no longer matches the alloc; and

 2) more importantly, the set_memory_ro() causes allocation of
    page tables for the normal memory that doesn't have any,
    and that later causes corruption and crashes (usually but
    not always in vfree()).

We could fix the first bug and use vmalloc() to work around the
second, but set_memory_ro() actually doesn't do anything either
so I'll just revert that as well.

Reported-by: Benjamin Berg <benjamin@sipsolutions.net>
Fixes: ef4459a6da09 ("um: allocate a guard page to helper threads")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

Since struct device is refcounted, we shouldn't free the vu_dev
immediately when it's removed from the platform device, but only
when the references actually all go away. Move the freeing to
the release to accomplish that.

Fixes: 5d38f324993f ("um: drivers: Add virtio vhost-user driver")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

This commit fixes a regression to handle command line parameters of ubd.
With a simple line "./linux ubd0="./disk-ext4.img", it fails at
ubd_setup_common().  The commit adds additional checks to the variables
in order to properly parse the paremeters which previously worked.

Fixes: ef3ba87cb7c9 ("um: ubd: Set device serial attribute from cmdline")
Cc: Christopher Obbard <chris.obbard@collabora.com>
Signed-off-by: Hajime Tazaki <thehajime@gmail.com>
Acked-by: Christopher Obbard <chris.obbard@collabora.com>
Signed-off-by: Richard Weinberger <richard@nod.at>