RE: [PATCH for-4.17 v2] hvm/apic: repurpose the reporting of the APIC assist options

[Henry Wang <Henry.Wang@arm.com>]

Hi Roger,

> Subject: Re: [PATCH for-4.17 v2] hvm/apic: repurpose the reporting of the
> APIC assist options
> 
> On 04/11/2022 16:18, Roger Pau Monne wrote:
> > The current reporting of the hardware assisted APIC options is done by
> > checking "virtualize APIC accesses" which is not very helpful, as that
> > feature doesn't avoid a vmexit, instead it does provide some help in
> > order to detect APIC MMIO accesses in vmexit processing.
> >
> > Repurpose the current reporting of xAPIC assistance to instead report
> > such feature as present when there's support for "TPR shadow" and
> > "APIC register virtualization" because in that case some xAPIC MMIO
> > register accesses are handled directly by the hardware, without
> > requiring a vmexit.
> >
> > For symetry also change assisted x2APIC reporting to require
> > "virtualize x2APIC mode" and "APIC register virtualization", dropping
> > the option to also be reported when "virtual interrupt delivery" is
> > available.  Presence of the "virtual interrupt delivery" feature will
> > be reported using a different option.
> >
> > Fixes: 2ce11ce249 ('x86/HVM: allow per-domain usage of hardware
> virtualized APIC')
> > Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
> > ---
> > Changes since v1:
> >   - Fix Viridian MSR tip conditions.
> 
> Reviewed-by: Paul Durrant <paul@xen.org>

Release-acked-by: Henry Wang <Henry.Wang@arm.com>

Kind regards,
Henry