When a pty is resized (using the TIOCSWINSZ ioctl -- see ioctl_tty(2)),
the kernel will send a SIGWINCH signal to the pty's foreground process
group to notify it of the resize. This is the only way to be notified
by the kernel of a pty resize.
We can't just make the cloud-hypervisor process's process group the
foreground process group though, because a process can only set the
foreground process group of its controlling terminal, and
cloud-hypervisor's controlling terminal will often be the terminal the
user is running it in. To work around this, we fork a subprocess in a
new process group, and set its process group to be the foreground
process group of the pty. The subprocess additionally must be running
in a new session so that it can have a different controlling
terminal. This subprocess writes a byte to a pipe every time the pty
is resized, and the virtio-console device can listen for this in its
epoll loop.
Alternatives I considered were to have the subprocess just send
SIGWINCH to its parent, and to use an eventfd instead of a pipe.
I decided against the signal approach because re-purposing a signal
that has a very specific meaning (even if this use was only slightly
different to its normal meaning) felt unclean, and because it would
have required using pidfds to avoid race conditions if
cloud-hypervisor had terminated, which added complexity. I decided
against using an eventfd because using a pipe instead allows the child
to be notified (via poll(2)) when nothing is reading from the pipe any
more, meaning it can be reliably notified of parent death and
terminate itself immediately.
I used clone3(2) instead of fork(2) because without
CLONE_CLEAR_SIGHAND the subprocess would inherit signal-hook's signal
handlers, and there's no other straightforward way to restore all signal
handlers to their defaults in the child process. The only way to do
it would be to iterate through all possible signals, or maintain a
global list of monitored signals ourselves (vmm:vm::HANDLED_SIGNALS is
insufficient because it doesn't take into account e.g. the SIGSYS
signal handler that catches seccomp violations).
Signed-off-by: Alyssa Ross <hi@alyssa.is>
This prepares us to be able to handle console resizes in the console
device's epoll loop, which we'll have to do if the output is a pty,
since we won't get SIGWINCH from it.
Signed-off-by: Alyssa Ross <hi@alyssa.is>
Musl often uses mmap to allocate memory where Glibc would use brk.
This has caused seccomp violations for me on the API and signal
handling threads.
Signed-off-by: Alyssa Ross <hi@alyssa.is>
As well as reducing the amount of code this also improves the binary
size slightly:
cargo bloat --release -n 2000 --bin cloud-hypervisor | grep virtio_devices::seccomp_filters::get_seccomp_rules
Before:
0.1% 0.2% 7.8KiB virtio_devices virtio_devices::seccomp_filters::get_seccomp_rules
After:
0.0% 0.1% 3.0KiB virtio_devices virtio_devices::seccomp_filters::get_seccomp_rules
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
This patch adds a separate function to launch two guest VMs and ensure
they are connected through ovs-dpdk, so that we can reuse this function
in other tests, e.g. the test for live-migration with ovs-dpdk.
Signed-off-by: Bo Chen <chen.bo@intel.com>
error: all if blocks contain the same code at the end
--> vmm/src/memory_manager.rs:884:9
|
884 | / Ok(mm)
885 | | }
| |_________^
Signed-off-by: Bo Chen <chen.bo@intel.com>
This concept ends up being broken with multiple types on input connected
e.g. console on TTY and serial on PTY. Already the code for checking for
injecting into the serial device checks that the serial is configured.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Introduce a common solution for spawning the virtio threads which will
make it easier to add the panic handling.
During this effort I discovered that there were no seccomp filters
registered for the vhost-user-net thread nor the vhost-user-block
thread. This change also incorporates basic seccomp filters for those as
part of the refactoring.
Signed-off-by: Rob Bradford <robert.bradford@intel.com>
Currently we need to test both device tree and ACPI on AArch64. As
the number of ACPI test cases is gradually increasing and expected
to increase in the future, it is better to extract all ACPI test
cases on AArch64 to a single module.
Signed-off-by: Henry Wang <Henry.Wang@arm.com>
