Re: [Xen-devel] [PATCH v5 07/21] x86/cpu: Move set_cpumask() calls into c_early_init()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 07.04.16 at 13:57, <andrew.cooper3@xxxxxxxxxx> wrote:
> Before c/s 44e24f8567 "x86: don't call generic_identify() redundantly", the
> commandline-provided masks would take effect in Xen's view of the processor
> features.
> 
> As the masks got applied after the query for features, the redundant call to
> generic_identify() would clobber the pre-masking feature information with the
> post-masking information.
> 
> Move the set_cpumask() calls into c_early_init() so the effects of the 
> command
> line parameters take place before the main query for features in
> generic_identify().
> 
> The cpuid_mask_* command line parameters now limit the entire system.
> Subsequent changes will cause the mask MSRs to be context switched 
> per-domain,
> removing the need to use the command line parameters for heterogeneous
> levelling purposes.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
with the previously mentioned constraint that due to the behavioral
change this shouldn't get committed independently of sufficiently
many of the following patches (until use of the masking command
line options is no longer necessary to control what PV guests get to
see).

Jan


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