Re: [Xen-devel] [PATCH v3.1 09/15] xen/x86: allow the emulated APICs to be enabled for the hardware domain

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

On Fri, Nov 04, 2016 at 03:19:11AM -0600, Jan Beulich wrote:
> >>> On 29.10.16 at 10:59, <roger.pau@xxxxxxxxxx> wrote:
> > --- a/xen/arch/x86/domain.c
> > +++ b/xen/arch/x86/domain.c
> > @@ -509,6 +509,27 @@ void vcpu_destroy(struct vcpu *v)
> >          xfree(v->arch.pv_vcpu.trap_ctxt);
> >  }
> >  
> > +static bool emulation_flags_ok(const struct domain *d, uint32_t emflags)
> > +{
> > +
> > +    if ( is_hvm_domain(d) )
> > +    {
> > +        if ( is_hardware_domain(d) &&
> > +             emflags != 
> > (XEN_X86_EMU_PIT|XEN_X86_EMU_LAPIC|XEN_X86_EMU_IOAPIC) )
> > +            return false;
> 
> Why are hardware domains required to get all three?

The PIT is always enabled for hardware domains, although we might consider 
disabling it for PVHv2 Dom0? TBH, I don't have a strong opinion here.

The local APIC and IO APIC are required in order to deliver interrupts from 
physical devices (this is only for PVHv2 hardware domains).

Roger.

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