Re: [Xen-devel] [PATCH v8 03/13] x86: maintain COS to CBM mapping for each socket

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.05.15 at 10:41, <chao.p.peng@xxxxxxxxxxxxxxx> wrote:
> For each socket, a COS to CBM mapping structure is maintained for each
> COS. The mapping is indexed by COS and the value is the corresponding
> CBM. Different VMs may use the same CBM, a reference count is used to
> indicate if the CBM is available.
> 
> Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> ---
> Changes in v8:
> * Move the memory allocation and CAT initialization code to CPU_UP_PREPARE.
> * Add memory freeing code in CPU_DEAD path.

Changes like this imo invalidate any tags given for earlier versions.

> +
> +    *rc = 0;
> +
> +    return;
> +
> +}
> +
> +

Stray return and blank lines.

> +static int cat_cpu_init(unsigned int cpu)
> +{
> +    int rc;
> +    const struct cpuinfo_x86 *c = cpu_data + cpu;
> +
> +    if ( !cpu_has(c, X86_FEATURE_CAT) )
> +        return 0;
> +
> +    if ( test_bit(cpu_to_socket(cpu), cat_socket_enable) )
> +        return 0;
> +
> +    if ( cpu == smp_processor_id() )
> +        do_cat_cpu_init(&rc);
> +    else
> +        on_selected_cpus(cpumask_of(cpu), do_cat_cpu_init, &rc, 1);

This now being called in the context of CPU_UP_PREPARE, I can't see
how this works at all: Neither would the CPU's cpu_data[] instance be
initialized by that time, nor would you be able to IPI that CPU, nor can I
see how the if() branch could ever get entered. Was this tested at all?

> @@ -283,14 +331,24 @@ static void psr_cpu_fini(unsigned int cpu)
>  static int cpu_callback(
>      struct notifier_block *nfb, unsigned long action, void *hcpu)
>  {
> +    int rc = 0;
>      unsigned int cpu = (unsigned long)hcpu;
>  
> -    if ( action == CPU_STARTING )
> -        psr_cpu_init();
> -    else if ( action == CPU_DEAD )
> +    switch ( action )
> +    {
> +    case CPU_UP_PREPARE:
> +        rc = psr_cpu_prepare(cpu);
> +        break;
> +    case CPU_STARTING:
> +        psr_cpu_starting();

This not being run for the boot CPU, ...

> @@ -305,7 +363,7 @@ static int __init psr_presmp_init(void)
>      if ( opt_psr & PSR_CAT )
>          init_psr_cat();
>  
> -    psr_cpu_init();
> +    psr_cpu_prepare(0);
>      if ( psr_cmt_enabled() || cat_socket_info )

... don't you need to call it here too?

Jan


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