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

[George Dunlap <george.dunlap@eu.citrix.com>]

On 11/12/2013 01:34 PM, Jan Beulich wrote:
>>>> On 11.11.13 at 15:57, George Dunlap <george.dunlap@eu.citrix.com> 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