Re: [Xen-devel] [PATCH v2 21/30] x86/pv: Provide custom cpumasks for PV domains

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 05.02.16 at 14:42, <andrew.cooper3@xxxxxxxxxx> wrote:
> --- a/xen/arch/x86/cpu/amd.c
> +++ b/xen/arch/x86/cpu/amd.c
> @@ -208,7 +208,9 @@ static void __init noinline probe_masking_msrs(void)
>  static void amd_ctxt_switch_levelling(const struct domain *nextd)
>  {
>       struct cpuidmasks *these_masks = &this_cpu(cpuidmasks);
> -     const struct cpuidmasks *masks = &cpuidmask_defaults;
> +     const struct cpuidmasks *masks =
> +            (nextd && is_pv_domain(nextd) && 
> nextd->arch.pv_domain.cpuidmasks)
> +            ? nextd->arch.pv_domain.cpuidmasks : &cpuidmask_defaults;

Mixing tabs and spaces for indentation.

> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -574,6 +574,11 @@ int arch_domain_create(struct domain *d, unsigned int 
> domcr_flags,
>              goto fail;
>          clear_page(d->arch.pv_domain.gdt_ldt_l1tab);
>  
> +        d->arch.pv_domain.cpuidmasks = xmalloc(struct cpuidmasks);
> +        if ( !d->arch.pv_domain.cpuidmasks )
> +            goto fail;
> +        *d->arch.pv_domain.cpuidmasks = cpuidmask_defaults;

Along the lines of not masking features for the hypervisor's own use
(see the respective comment on the earlier patch) I think this patch,
here or in domain_build.c, should except Dom0 from having the
default masking applied. This shouldn't, however, extend to CPUID
faulting. (Perhaps this rather belongs here so that the non-Dom0
hardware domain case can also be taken care of.)

Jan


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