The Big QEMU Lock (BQL) has many names and they are confusing. The
actual QemuMutex variable is called qemu_global_mutex but it's commonly
referred to as the BQL in discussions and some code comments. The
locking APIs, however, are called qemu_mutex_lock_iothread() and
qemu_mutex_unlock_iothread().
The "iothread" name is historic and comes from when the main thread was
split into into KVM vcpu threads and the "iothread" (now called the main
loop thread). I have contributed to the confusion myself by introducing
a separate --object iothread, a separate concept unrelated to the BQL.
The "iothread" name is no longer appropriate for the BQL. Rename the
locking APIs to:
- void bql_lock(void)
- void bql_unlock(void)
- bool bql_locked(void)
There are more APIs with "iothread" in their names. Subsequent patches
will rename them. There are also comments and documentation that will be
updated in later patches.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Acked-by: Fabiano Rosas <farosas@suse.de>
Acked-by: David Woodhouse <dwmw@amazon.co.uk>
Reviewed-by: Cédric Le Goater <clg@kaod.org>
Acked-by: Peter Xu <peterx@redhat.com>
Acked-by: Eric Farman <farman@linux.ibm.com>
Reviewed-by: Harsh Prateek Bora <harshpb@linux.ibm.com>
Acked-by: Hyman Huang <yong.huang@smartx.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-id: 20240102153529.486531-2-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The SRC device is normally used to start the secondary CPU.
When running Linux directly, QEMU is emulating a PSCI interface that UBOOT
is installing at boot time and therefore the fact that the SRC device is
unimplemented is hidden as Qemu respond directly to PSCI requets without
using the SRC device.
But if you try to run a more bare metal application (maybe uboot itself),
then it is not possible to start the secondary CPU as the SRC is an
unimplemented device.
This patch adds the ability to start the secondary CPU through the SRC
device so that you can use this feature in bare metal applications.
Signed-off-by: Jean-Christophe Dubois <jcd@tribudubois.net>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: ce9a0162defd2acee5dc7f8a674743de0cded569.1692964892.git.jcd@tribudubois.net
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
