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ui/console: ensure do_safe_dpy_refresh holds BQL

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I missed the fact that when an exclusive work item runs it drops the
BQL to ensure all no vCPUs are stuck waiting for it, hence causing a
deadlock. However the actual helper needs to take the BQL especially
as we'll be messing with device emulation bits during the update which
all assume BQL is held.

We make a minor cpu_reloading_memory_map which must try and unlock the
RCU if we are actually outside the running context.

Reported-by: Laurent Desnogues <laurent.desnogues@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Alex Bennée 2017-03-22 16:11:13 +00:00
parent 95992b674c
commit 8539093919
2 changed files with 3 additions and 1 deletions
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2
cpu-exec-common.c
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@ -35,7 +35,7 @@ void cpu_loop_exit_noexc(CPUState *cpu)
#if defined(CONFIG_SOFTMMU)
void cpu_reloading_memory_map(void)
{
if (qemu_in_vcpu_thread()) {
if (qemu_in_vcpu_thread() && current_cpu->running) {
/* The guest can in theory prolong the RCU critical section as long
* as it feels like. The major problem with this is that because it
* can do multiple reconfigurations of the memory map within the

2
ui/console.c
View file

@ -1586,7 +1586,9 @@ bool dpy_gfx_check_format(QemuConsole *con,
static void do_safe_dpy_refresh(CPUState *cpu, run_on_cpu_data opaque)
{
DisplayChangeListener *dcl = opaque.host_ptr;
qemu_mutex_lock_iothread();
dcl->ops->dpy_refresh(dcl);
qemu_mutex_unlock_iothread();
}
static void dpy_refresh(DisplayState *s)