Re: [Qemu-devel] [RFC v2 0/5] Dynamic TLB sizing

["Emilio G. Cota" <cota@braap.org>]

On Tue, Oct 09, 2018 at 15:45:36 +0100, Alex Bennée wrote:
> 
> Emilio G. Cota <cota@braap.org> writes:
> 
> > On Tue, Oct 09, 2018 at 13:34:40 +0100, Alex Bennée wrote:
> >>
> >> Emilio G. Cota <cota@braap.org> writes:
> >>
> >> > v1: https://lists.gnu.org/archive/html/qemu-devel/2018-10/msg01146.html
> >> >
> >> > Changes since v1:
> >>
> >> Hmm I'm seeing some qtest failures, for example:
> >>
> >>   $ make check-qtest-alpha V=1
> >>   ...
> >>   QTEST_QEMU_BINARY=alpha-softmmu/qemu-system-alpha QTEST_QEMU_IMG=qemu-img MALLOC_PERTURB_=${MALLOC_PERTURB_:-$(( ${RANDOM:-0} % 255 + 1))} gtester -k --verbose -m=quick test
> >>   s/boot-serial-test tests/qmp-test tests/qmp-cmd-test tests/device-introspect-test tests/cdrom-test tests/machine-none-test tests/qom-test tests/test-hmp
> >>   TEST: tests/boot-serial-test... (pid=31091)
> >>     /alpha/boot-serial/clipper:                                          Broken pipe
> >>   tests/libqtest.c:129: kill_qemu() detected QEMU death from signal 11 (Segmentation fault) (core dumped)
> >>   FAIL
> >>   GTester: last random seed: R02S948c4a5112fd7682934f4d96e1aff38e
> >>   (pid=31099)
> >>   FAIL: tests/boot-serial-test
> >
> > I'm pretty sure that the problem is that tlb_init is not being
> > called at all. Note that this applies to the tlb-lock series
> > as well, although there we're just calling qemu_spin_init,
> > which is not really necessary because CPUArchState is 0-allocated.
> >
> > I'll take a look.
> 
> Yeah I hadn't tried to bisect it, but I'm on top of tlb-lock-v4 as
> requested.

It's the tlb_flush in alpha_cpu_initfn:

static void alpha_cpu_initfn(Object *obj)
{
    CPUState *cs = CPU(obj);
    AlphaCPU *cpu = ALPHA_CPU(obj);
    CPUAlphaState *env = &cpu->env;

    cs->env_ptr = env;
    tlb_flush(cs);

We call tlb_init later on at realize time.

I think we can safely get rid of this tlb_flush. Unicore
also has it. I'll add patches for both to the tlb-lock series.

		Emilio