Commit 00961090 authored by Alex Bennée's avatar Alex Bennée
Browse files

ui/console: use exclusive mechanism directly 



The previous commit (8bb93c6f) using async_safe_run_on_cpu() doesn't
work on graphics sub-system which restrict which threads can do GUI
updates. Rather the special casing MacOS we just directly call the
helper and move all the exclusive handling into do_dafe_dpy_refresh().

The unfortunate bouncing of the BQL is to ensure there is no deadlock
as vCPUs waiting on the BQL are kicked into their quiescent state.

Signed-off-by: default avatarAlex Bennée <alex.bennee@linaro.org>
Reviewed-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarGerd Hoffmann <kraxel@redhat.com>
parent 85390939

ui/console.c

+9 −7
Original line number Diff line number Diff line
@@ -1576,19 +1576,22 @@ bool dpy_gfx_check_format(QemuConsole *con, 
}



/*

 * Safe DPY refresh for TCG guests. This runs when the TCG vCPUs are

 * quiescent so we can avoid races between dirty page tracking for

 * direct frame-buffer access by the guest.

 * Safe DPY refresh for TCG guests. We use the exclusive mechanism to

 * ensure the TCG vCPUs are quiescent so we can avoid races between

 * dirty page tracking for direct frame-buffer access by the guest.

 *

 * This is a temporary stopgap until we've fixed the dirty tracking

 * races in display adapters.

 */

static void do_safe_dpy_refresh(CPUState *cpu, run_on_cpu_data opaque)

static void do_safe_dpy_refresh(DisplayChangeListener *dcl)

{

    DisplayChangeListener *dcl = opaque.host_ptr;

    qemu_mutex_unlock_iothread();

    start_exclusive();

    qemu_mutex_lock_iothread();

    dcl->ops->dpy_refresh(dcl);

    qemu_mutex_unlock_iothread();

    end_exclusive();

    qemu_mutex_lock_iothread();

}



static void dpy_refresh(DisplayState *s)
@@ -1598,8 +1601,7 @@ static void dpy_refresh(DisplayState *s) 
    QLIST_FOREACH(dcl, &s->listeners, next) {

        if (dcl->ops->dpy_refresh) {

            if (tcg_enabled()) {

                async_safe_run_on_cpu(first_cpu, do_safe_dpy_refresh,

                                      RUN_ON_CPU_HOST_PTR(dcl));

                do_safe_dpy_refresh(dcl);

            } else {

                dcl->ops->dpy_refresh(dcl);

            }