Re: [PATCH v6 04/11] common: add vmtrace_pt_size domain parameter

[Jan Beulich <jbeulich@xxxxxxxx>]

On 07.07.2020 21:39, Michał Leszczyński wrote:
> @@ -443,6 +449,9 @@ struct domain *domain_create(domid_t domid,
>          d->nr_pirqs = min(d->nr_pirqs, nr_irqs);
>  
>          radix_tree_init(&d->pirq_tree);
> +
> +        if ( config->processor_trace_buf_kb )
> +            d->processor_trace_buf_kb = config->processor_trace_buf_kb;

There's no real need for the if, is there?

> --- a/xen/include/public/domctl.h
> +++ b/xen/include/public/domctl.h
> @@ -92,6 +92,7 @@ struct xen_domctl_createdomain {
>      uint32_t max_evtchn_port;
>      int32_t max_grant_frames;
>      int32_t max_maptrack_frames;
> +    uint32_t processor_trace_buf_kb;

Adding a new field to an existing interface struct requires bumping
of the interface version, unless that has already happened during a
release cycle.

Here I agree with the choice of uint32_t, but ...

> --- a/xen/include/xen/sched.h
> +++ b/xen/include/xen/sched.h
> @@ -457,6 +457,9 @@ struct domain
>      unsigned    pbuf_idx;
>      spinlock_t  pbuf_lock;
>  
> +    /* Used by vmtrace features */
> +    uint32_t    processor_trace_buf_kb;

... why a fixed size type here? unsigned int will do fine, won't it?

Jan