Re: [Xen-devel] [PATCH v7 12/32] xen/x86: add bitmap of enabled emulated devices

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

El 06/10/15 a les 13.05, George Dunlap ha escrit:
> On 05/10/15 10:34, Andrew Cooper wrote:
>> On 02/10/15 16:48, Roger Pau Monne wrote:
>>> Introduce a bitmap in x86 xen_arch_domainconfig that allows enabling or
>>> disabling specific devices emulated inside of Xen for HVM guests.
>>>
>>> Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
>>> Acked-by: Wei Liu <wei.liu2@xxxxxxxxxx>
>>> Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
>>> Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
>>> Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
>>> Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
>>> Cc: Jan Beulich <jbeulich@xxxxxxxx>
>>> Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>>> Cc: George Dunlap <george.dunlap@xxxxxxxxxxxxx>
>>
>> Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, with 2 small
>> suggestions.
>>
>>> diff --git a/xen/common/schedule.c b/xen/common/schedule.c
>>> index 5ffa1a1..aeb911e 100644
>>> --- a/xen/common/schedule.c
>>> +++ b/xen/common/schedule.c
>>> @@ -1428,6 +1428,9 @@ static struct notifier_block cpu_schedule_nfb = {
>>>  /* Initialise the data structures. */
>>>  void __init scheduler_init(void)
>>>  {
>>> +#ifdef CONFIG_X86
>>> +    struct xen_arch_domainconfig config = { .emulation_flags = 0 };
>>> +#endif
>>>      struct domain *idle_domain;
>>>      int i;
>>>  
>>> @@ -1474,8 +1477,11 @@ void __init scheduler_init(void)
>>>          sched_ratelimit_us = SCHED_DEFAULT_RATELIMIT_US;
>>>      }
>>>  
>>> -    /* There is no need of arch-specific configuration for an idle domain 
>>> */
>>> +#ifdef CONFIG_X86
>>> +    idle_domain = domain_create(DOMID_IDLE, 0, 0, &config);
>>> +#else
>>>      idle_domain = domain_create(DOMID_IDLE, 0, 0, NULL);
>>> +#endif
>>
>> You could get away without this ifdefary if you have
>>
>> #else
>>     void *config = NULL;
>>
>> In the previous hunk.
> 
> It would be even better if you could do what arm does, and accept NULL
> configurations for the idle, xen, io, and cow domains.

I'm not sure of that. HVM domains certainly require config to be
provided, while PV domains could do without it. IMHO it's better for
consistency of interfaces to always require a valid arch config rather
than make it depend on the domain type.

Roger.


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