Re: [PATCH v2 0/3] Change default pointer authentication algorithm on aarch64 to impdef

[Pierrick Bouvier]

On 1/13/25 11:32, Pierrick Bouvier wrote:
> On 1/13/25 04:34, Peter Maydell wrote:
> > On Fri, 10 Jan 2025 at 16:28, Peter Maydell <peter.maydell@linaro.org> wrote:
> > > On Thu, 19 Dec 2024 at 18:32, Pierrick Bouvier
> > > <pierrick.bouvier@linaro.org> wrote:
> > > > qemu-system-aarch64 default pointer authentication (QARMA5) is expensive, we
> > > > spent up to 50% of the emulation time running it (when using TCG).
> > > >
> > > > Switching to pauth-impdef=on is often given as a solution to speed up execution.
> > > > Thus we talked about making it the new default.
> > > >
> > > > The first patch introduce a new property (pauth-qarma5) to allow to select
> > > > current default algorithm.
> > > > The second one change the default.
> > > > The third one updates documentation.
> > > >
> > > > v2:
> > > > - ensure we don't break migration compatibility, by using a specific backward
> > > >     compatible property.
> > > > - added some documentation about migration for arm virt machine model.
> > >
> > > Other than a minor change to the 3rd docs patch which I'll note there:
> > > applied to target-arm.next, thanks.
> >
> > I just noticed that this series breaks 'make check-tcg', because
> > the pauth-3 test is explicitly checking the output of the
> > pointer-auth operation. I'm going to add in this patch, which
> > goes between patches 1 and 2 of this series:
> >
> > Author: Peter Maydell <peter.maydell@linaro.org>
> > Date:   Mon Jan 13 11:42:57 2025 +0000
> >
> >       tests/tcg/aarch64: force qarma5 for pauth-3 test
> >
> >       The pauth-3 test explicitly tests that a computation of the
> >       pointer-authentication produces the expected result.  This means that
> >       it must be run with the QARMA5 algorithm.
> >
> >       Explicitly set the pauth algorithm when running this test, so that it
> >       doesn't break when we change the default algorithm the 'max' CPU
> >       uses.
> >
> >       Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> >
> > diff --git a/tests/tcg/aarch64/Makefile.softmmu-target
> > b/tests/tcg/aarch64/Makefile.softmmu-target
> > index d08d9b01ded..9c52475b7ae 100644
> > --- a/tests/tcg/aarch64/Makefile.softmmu-target
> > +++ b/tests/tcg/aarch64/Makefile.softmmu-target
> > @@ -91,6 +91,9 @@ EXTRA_RUNS+=run-memory-replay
> >
> >    ifneq ($(CROSS_CC_HAS_ARMV8_3),)
> >    pauth-3: CFLAGS += $(CROSS_CC_HAS_ARMV8_3)
> > +# This test explicitly checks the output of the pauth operation so we
> > +# must force the use of the QARMA5 algorithm for it.
> > +run-pauth-3: QEMU_BASE_MACHINE=-M virt -cpu max,pauth-qarma5=on -display none
> >    else
> >    pauth-3:
> >           $(call skip-test, "BUILD of $@", "missing compiler support")
> >
> >
> > thanks
> > -- PMM
>
> Thanks Peter.
>
> I'm a bit surprised because I ran all tests , and didn't find any failure.
>
> I use container 'debian-all-test-cross' and ran 'make check-tcg'. Is the
> container missing something that doesn't trigger this test?

I found that the build step I was using:
- ./configure $QEMU_CONFIGURE_OPTS
only builds user targets in this container.
But failing test is related to a system target.

I updated this on my side, to make sure I won't miss that next time.

Thanks again for the fix.

Regards,
Pierrick