On 09.11.2020 10:50, Juergen Gross wrote:
> @@ -83,14 +85,28 @@ void passive_domain_destroy(struct vcpu *v)
> model->free_msr(v);
> }
>
> +bool nmi_oprofile_send_virq(void)
> +{
> + struct vcpu *v = this_cpu(nmi_cont_vcpu);
> +
> + if ( v )
> + send_guest_vcpu_virq(v, VIRQ_XENOPROF);
> +
> + this_cpu(nmi_cont_vcpu) = NULL;
What if, by the time we make it here, a 2nd NMI has arrived? I
agree the next overflow interrupt shouldn't arrive this
quickly, but I also think you want to zap the per-CPU variable
first here, and ...
> +
> + return v;
> +}
> +
> static int nmi_callback(const struct cpu_user_regs *regs, int cpu)
> {
> int xen_mode, ovf;
>
> ovf = model->check_ctrs(cpu, &cpu_msrs[cpu], regs);
> xen_mode = ring_0(regs);
> - if ( ovf && is_active(current->domain) && !xen_mode )
> - send_guest_vcpu_virq(current, VIRQ_XENOPROF);
> + if ( ovf && is_active(current->domain) && !xen_mode ) {
> + this_cpu(nmi_cont_vcpu) = current;
... avoid overwriting any non-NULL value here. That's then of
course still not closing the window, but has (imo) overall
better behavior.
Also, style-wise, going through the file it looks to be mainly
Linux style, so may I suggest your additions / changes to be
done that way, rather than extending use of this funny mixed
style?
Jan
