Re: [Xen-devel] [PATCH v3 07/28] xen/x86: Annotate special features

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Mar 15, 2016 at 03:35:03PM +0000, Andrew Cooper wrote:
> Some bits in a featureset are not simple a indication of new functionality,
> and require special handling.
> 
> APIC, OSXSAVE and OSPKE are fast-forwards of other pieces of state;
> IA32_APIC_BASE.EN, CR4.OSXSAVE and CR4.OSPKE.  Xen will take care of filling
> these appropriately at runtime.
> 
> FDP_EXCP_ONLY and NO_FPU_SEL are bits indicating reduced functionality in the
> x87 pipeline.  The effects of these cannot be hidden from the guest, so the
> host values will always be provided.
> 
> HTT and CMP_LEGACY indicate how to interpret other cpuid leaves.  In most
> cases, the toolstack value will be used (with the expectation that these flags
> will match the other provided topology information).  However with cpuid
> masking, the host values are presented as masking cannot influence what the
> guest sees in the dependent leaves.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

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