Hi Alex, this patch breaks:
http://wiki.qemu.org/download/arm-test-0.2.tar.gz qemu-system-arm -kernel zImage.integrator -initrd arm_root.img -append "console=ttyAMA0" -machine integratorcp -serial stdio -icount 0 Uncompressing Linux.......................................................................... done, booting the kernel. qemu-system-arm: /work/qemu/qemu/memory.c:920: memory_region_transaction_commit: Assertion `qemu_mutex_iothread_locked()' failed. The backtrace looks like this: #4 0x00005555557ced26 in memory_region_transaction_commit () at /work/qemu/qemu/memory.c:920 #5 0x0000555555959b82 in pl110_update_display (opaque=0x555556a839e0) at hw/display/pl110.c:245 #6 0x0000555555a60931 in sdl_refresh (dcl=0x555556b90d40) at ui/sdl.c:821 #7 0x00005555558f9f91 in process_queued_cpu_work ( cpu=cpu@entry=0x5555566c6810) at cpus-common.c:338 #8 0x00005555557ba5a8 in qemu_wait_io_event_common ( cpu=cpu@entry=0x5555566c6810) at /work/qemu/qemu/cpus.c:1027 #9 0x00005555557ba9bb in qemu_tcg_wait_io_event (cpu=cpu@entry=0x5555566c6810) at /work/qemu/qemu/cpus.c:1048 #10 0x00005555557bc2bd in qemu_tcg_cpu_thread_fn (arg=0x5555566c6810) at /work/qemu/qemu/cpus.c:1440 #11 0x00007ffff5f4a6ba in start_thread (arg=0x7fffee650700) at pthread_create.c:333 #12 0x00007ffff5c8082d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 BTW is it easier if I enter such bug reports in QEMU launchpad? Thanks, Laurent On Wed, Mar 15, 2017 at 3:48 PM, Alex Bennée <alex.ben...@linaro.org> wrote: > Commit 8d04fb55.. > > tcg: drop global lock during TCG code execution > > ..broke the assumption that updates to the GUI couldn't happen at the > same time as TCG vCPUs where running. As a result the TCG vCPU could > still be updating a directly mapped frame-buffer while the display > side was updating. This would cause artefacts to appear when the > update code assumed that memory block hadn't changed. > > The simplest solution is to ensure the two things can't happen at the > same time like the old BQL locking scheme. Here we use the solution > introduced for MTTCG and schedule the update as async_safe_work when > we know no vCPUs can be running. > > Reported-by: Mark Cave-Ayland <mark.cave-ayl...@ilande.co.uk> > Cc: BALATON Zoltan <bala...@eik.bme.hu> > Cc: Gerd Hoffmann <kra...@redhat.com> > Signed-off-by: Alex Bennée <alex.ben...@linaro.org> > --- > ui/console.c | 18 +++++++++++++++++- > 1 file changed, 17 insertions(+), 1 deletion(-) > > diff --git a/ui/console.c b/ui/console.c > index d1ff7504ec..37a69e27de 100644 > --- a/ui/console.c > +++ b/ui/console.c > @@ -1575,13 +1575,29 @@ bool dpy_gfx_check_format(QemuConsole *con, > return true; > } > > +/* > + * 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. > + */ > +static void do_safe_dpy_refresh(CPUState *cpu, run_on_cpu_data opaque) > +{ > + DisplayChangeListener *dcl = opaque.host_ptr; > + dcl->ops->dpy_refresh(dcl); > +} > + > static void dpy_refresh(DisplayState *s) > { > DisplayChangeListener *dcl; > > QLIST_FOREACH(dcl, &s->listeners, next) { > if (dcl->ops->dpy_refresh) { > - dcl->ops->dpy_refresh(dcl); > + if (tcg_enabled()) { > + async_safe_run_on_cpu(first_cpu, do_safe_dpy_refresh, > + RUN_ON_CPU_HOST_PTR(dcl)); > + } else { > + dcl->ops->dpy_refresh(dcl); > + } > } > } > } > -- > 2.11.0 > >
