Re: 'make check-tcg' fails with an assert in qemu_plugin_vcpu_init_hook

[Peter Maydell]

On Wed, 21 Jun 2023 at 09:05, Alex Bennée <alex.bennee@linaro.org> wrote:
>
>
> Peter Maydell <peter.maydell@linaro.org> writes:
>
> > On Tue, 20 Jun 2023 at 17:56, Peter Maydell <peter.maydell@linaro.org> 
> > wrote:
> >>
> >> $ make -C build/x86 check-tcg
> >> make: Entering directory 
> >> '/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/x86'
> >> [...]
> >>   TEST    munmap-pthread on arm
> >> **
> >> ERROR:../../plugins/core.c:221:qemu_plugin_vcpu_init_hook: assertion
> >> failed: (success)
> >> **
> >> ERROR:../../accel/tcg/cpu-exec.c:1024:cpu_exec_setjmp: assertion
> >> failed: (cpu == current_cpu)
> >
> > git bisect blames commit d7ee93e2435970:
> >
> >     cputlb: Restrict SavedIOTLB to system emulation
> >
> > I think that commit is not correct, because it means that
> > the size of 'struct CPUState' and also the offset of fields
> > like 'cpu_index' will be different for files which are
> > compile-per-target-for-usermode and files which are
> > compile-once-only. The assert happens here because the
> > code which sets up cpu_index is build-once, but the code
> > in qemu_plugin_vcpu_init_hook() which reads cpu_index is
> > build-per-target and now they don't agree about where in
> > the struct the field is...
>
> Hmm two things from that imply:
>
>   - I suspect the plugin core stuff could be build once (or maybe twice,
>     system and user)

It is already build-once, that's why it goes wrong...

>   - we need to have some guard rails somehow to make sure things don't
>     go out of sync

We do, this is the poison.h stuff. CONFIG_USER_ONLY is a
special case which we don't poison because there would be
too much refactoring required...

-- PMM