Re: [Xen-devel] [PATCH] x86: report use of PCID together with reporting XPTI status

[Doug Goldstein <cardoe@xxxxxxxxxx>]

On Mon, Jul 16, 2018 at 10:45:15AM -0600, Jan Beulich wrote:
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> --- a/xen/arch/x86/pv/domain.c
> +++ b/xen/arch/x86/pv/domain.c
> @@ -288,6 +288,12 @@ int pv_domain_initialise(struct domain *
>      return rc;
>  }
>  
> +bool __init xpti_pcid_enabled(void)
> +{
> +    return use_invpcid && cpu_has_pcid &&
> +           (opt_pcid == PCID_ALL || opt_pcid == PCID_XPTI);
> +}
> +
>  static void _toggle_guest_pt(struct vcpu *v)
>  {
>      const struct domain *d = v->domain;
> --- a/xen/arch/x86/spec_ctrl.c
> +++ b/xen/arch/x86/spec_ctrl.c
> @@ -256,9 +256,10 @@ static void __init print_details(enum in
>             boot_cpu_has(X86_FEATURE_SC_RSB_HVM)      ? " RSB"           : "",
>             opt_eager_fpu                             ? " EAGER_FPU"     : 
> "");
>  
> -    printk("  XPTI (64-bit PV only): Dom0 %s, DomU %s\n",
> +    printk("  XPTI (64-bit PV only): Dom0 %s, DomU %s (with%s PCID)\n",

Do you ever foresee wanting to add another flag in here? It might be
better to just have "with: %s" and do xpti_pcid_enabled ? "PCID" : "" if
you do. If not then this seems like a good addition to me and is
definitely welcome to folks wanting to know if they're using PCID.

Reviewed-by: Doug Goldstein <cardoe@xxxxxxxxxx>

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