Re: [Xen-devel] [PATCH v15 05/19] pvh prep: Introduce pv guest type and has_hvm_container macros

[George Dunlap <george.dunlap@xxxxxxxxxxxxx>]

On 11/12/2013 01:34 PM, Jan Beulich wrote:
> > > > On 11.11.13 at 15:57, George Dunlap <george.dunlap@xxxxxxxxxxxxx> wrote:
> > --- a/xen/arch/x86/acpi/suspend.c
> > +++ b/xen/arch/x86/acpi/suspend.c
> > @@ -85,7 +85,7 @@ void restore_rest_processor_state(void)
> >           BUG();
> >
> >       /* Maybe load the debug registers. */
> > -    BUG_ON(is_hvm_vcpu(curr));
> > +    BUG_ON(!is_pv_vcpu(curr));
> >       if ( !is_idle_vcpu(curr) && curr->arch.debugreg[7] )
> >       {
> >           write_debugreg(0, curr->arch.debugreg[0]);
> This is certainly fine for now, but I guess in the long run (i.e. when
> supporting Dom0) this will need changing from BUG_ON() to
> integrating the condition with the if().
Yes -- the BUG_ON() was to make sure someone thinks carefully about what 
the right thing is to do here.  I suppose there should have been a fixme 
here as well, however.
> > @@ -1246,8 +1246,7 @@ void arch_get_info_guest(struct vcpu *v, 
> > vcpu_guest_context_u c)
> >       bool_t compat = is_pv_32on64_domain(v->domain);
> >   #define c(fld) (!compat ? (c.nat->fld) : (c.cmp->fld))
> >
> > -    if ( is_hvm_vcpu(v) )
> > -        memset(c.nat, 0, sizeof(*c.nat));
> > +    memset(c.nat, 0, sizeof(*c.nat));
> Removing the conditional is both dangerous and unmotivated:
> Dangerous because you now assume that the space allocated is
> always covering the (larger) native size (this currently happens to
> be that way in the only caller, but isn't guaranteed). And
> unmotivated because switching just the conditional (as done
> throughout the rest of the patch) would have sufficed here.
Indeed, I can't think of why I didn't change it to "!is_pv_vcpu()" here.

 -George


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