Re: [Xen-devel] [PATCH 5/9] x86/pvh: Set PVH guest's mode in XEN_DOMCTL_set_address_size

[Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>]

On 06/24/2015 08:10 AM, Jan Beulich wrote:
> > > > On 24.06.15 at 13:42, <boris.ostrovsky@xxxxxxxxxx> wrote:
> > On 06/24/2015 03:57 AM, Jan Beulich wrote:
> > > > > > On 24.06.15 at 04:53, <boris.ostrovsky@xxxxxxxxxx> wrote:
> > > > On 06/23/2015 09:22 AM, Jan Beulich wrote:
> > > > > > --- a/xen/arch/x86/hvm/hvm.c
> > > > > > +++ b/xen/arch/x86/hvm/hvm.c
> > > > > > @@ -2320,12 +2320,7 @@ int hvm_vcpu_initialise(struct vcpu *v)
> > > > > >         v->arch.hvm_vcpu.inject_trap.vector = -1;
> > > > > >     
> > > > > >         if ( is_pvh_domain(d) )
> > > > > > -    {
> > > > > > -        v->arch.hvm_vcpu.hcall_64bit = 1;    /* PVH 32bitfixme. */
> > > > > > -        /* This is for hvm_long_mode_enabled(v). */
> > > > > > -        v->arch.hvm_vcpu.guest_efer = EFER_LMA | EFER_LME;
> > > > > >             return 0;
> > > > > > -    }
> > > > > With this removed, is there any guarantee that hvm_set_mode()
> > > > > will be called for each vCPU?
> > > > IIUIC, toolstack is required to call XEN_DOMCTL_set_address_size which
> > > > results in a call to switch_compat/native(), which loop over all VCPUs,
> > > > calling set_mode.
> > > I don't recall this being a strict requirement. I think a PV 64-bit
> > > guest would start fine without.
> > We do call it via libxl__build_pv() -> xc_dom_boot_mem_init() ->
> > arch_setup_mem_init() -> x86_compat().
> Right, that's in our tool stack. The question though was whether it's
> a requirement to be called.
Since this change will assume that this domctl is called for both 32- 
and 64-bit --- yes, this becomes a requirement for 64-bit PVH guests.
boris


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