Re: [Xen-devel] [PATCH v2 12/23] x86: monitor.o is currently HVM only

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

On 8/29/18 8:43 PM, Tamas K Lengyel wrote:
> On Wed, Aug 29, 2018 at 10:42 AM Wei Liu <wei.liu2@xxxxxxxxxx> wrote:
>>
>> On Mon, Aug 27, 2018 at 09:18:29AM -0600, Jan Beulich wrote:
>>>>>> On 26.08.18 at 14:19, <wei.liu2@xxxxxxxxxx> wrote:
>>>> There has been plan to make PV work, but it is not yet there.  Provide
>>>> stubs to make it build with !CONFIG_HVM.
>>>>
>>>> Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
>>>> ---
>>>>  xen/arch/x86/Makefile         |  2 +-
>>>>  xen/include/asm-x86/monitor.h | 14 ++++++++++++++
>>>>  2 files changed, 15 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
>>>> index 9b9b63a..43f9189 100644
>>>> --- a/xen/arch/x86/Makefile
>>>> +++ b/xen/arch/x86/Makefile
>>>> @@ -45,7 +45,7 @@ obj-y += microcode_amd.o
>>>>  obj-y += microcode_intel.o
>>>>  obj-y += microcode.o
>>>>  obj-y += mm.o x86_64/mm.o
>>>> -obj-y += monitor.o
>>>> +obj-$(CONFIG_HVM) += monitor.o
>>>>  obj-y += mpparse.o
>>>>  obj-y += nmi.o
>>>>  obj-y += numa.o
>>>> diff --git a/xen/include/asm-x86/monitor.h b/xen/include/asm-x86/monitor.h
>>>> index 4988903..09f7f8a 100644
>>>> --- a/xen/include/asm-x86/monitor.h
>>>> +++ b/xen/include/asm-x86/monitor.h
>>>> @@ -99,10 +99,24 @@ static inline uint32_t
>>>> arch_monitor_get_capabilities(struct domain *d)
>>>>  int arch_monitor_domctl_event(struct domain *d,
>>>>                                struct xen_domctl_monitor_op *mop);
>>>>
>>>> +#ifdef CONFIG_HVM
>>>> +
>>>>  int arch_monitor_init_domain(struct domain *d);
>>>>
>>>>  void arch_monitor_cleanup_domain(struct domain *d);
>>>>
>>>> +#else
>>>> +
>>>> +static inline int arch_monitor_init_domain(struct domain *d)
>>>> +{
>>>> +    return 0;
>>>> +}
>>>> +
>>>> +static inline void arch_monitor_cleanup_domain(struct domain *d)
>>>> +{}
>>>> +
>>>> +#endif
>>>
>>> Wouldn't the entire XEN_DOMCTL_VM_EVENT_OP_MONITOR case
>>> in vm_event_domctl() then better be put in an #ifdef instead?
>>
>> I didn't do that because that was common to both ARM and x86.
>>
>> But now looking at the ARM counterpart, it is not supported either. When
>> it is eventually supported on ARM, it will be likely to be dependent on
>> CONFIG_HVM anyway. So I think I can put XEN_DOMCTL_VM_EVENT_OP_MONITOR
>> under CONFIG_HVM.
>>
> 
> It is not that it is not supported, it is that it's not (yet) needed.
> I think it would be better to have ifdef CONFIG_HVM only in code
> that's reached on x86 and not common ones.

FWIW, I agree with Tamas here.


Thanks,
Razvan

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