Re: [PATCH] cpus: verify that number of created cpus do not exceed smp params

[Pavel Dovgalyuk]

On 23.10.2020 11:10, Philippe Mathieu-Daudé wrote:
> On 10/23/20 9:34 AM, Pavel Dovgalyuk wrote:
> > Machine definitions may miss some vCPU-related parameters.
> > E.g., xlnx-versal-virt missed min_cpus and it was set to 1 by default.
> > This allowed using -smp 1 command line argument. But the machine
> > still created 2 vCPUs and passed all checks.
> > This patch adds one more check that does not allow creating
> > extra cpus that exceed the values specified in machine/smp.
> >
> > Signed-off-by: Pavel Dovgalyuk <pavel.dovgalyuk@ispras.ru>
> > ---
> >   0 files changed
> >
> > diff --git a/softmmu/cpus.c b/softmmu/cpus.c
> > index 47cceddd80..da74794e09 100644
> > --- a/softmmu/cpus.c
> > +++ b/softmmu/cpus.c
> > @@ -603,6 +603,11 @@ void qemu_init_vcpu(CPUState *cpu)
> >   {
> >       MachineState *ms = MACHINE(qdev_get_machine());
> > +    if (cpu->cpu_index >= ms->smp.cpus) {
> > +        fprintf(stderr, "Machine definition error: trying to create 
> > too many CPUs\n");
> > +        exit(1);
>
> Shouldn't this be an assert()?

I thought about this.
Bugs could be unnoticed and reveal in release. Therefore user should 
know the details and shouldn't see an assert.

> > +    }
> > +
> >       cpu->nr_cores = ms->smp.cores;
> >       cpu->nr_threads =  ms->smp.threads;
> >       cpu->stopped = true;