linux-kernel - Re: [PATCH 2/8] xen/balloon: Move common memory reservation routines to a module

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Date:   Thu, 31 May 2018 17:29:09 +0300
From:   Oleksandr Andrushchenko <andr2000@...il.com>
To:     Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        xen-devel@...ts.xenproject.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-media@...r.kernel.org,
        jgross@...e.com, konrad.wilk@...cle.com
Cc:     daniel.vetter@...el.com, dongwon.kim@...el.com,
        matthew.d.roper@...el.com,
        Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Subject: Re: [PATCH 2/8] xen/balloon: Move common memory reservation routines
 to a module

On 05/31/2018 10:51 AM, Oleksandr Andrushchenko wrote:
> On 05/30/2018 10:24 PM, Boris Ostrovsky wrote:
>> On 05/30/2018 01:46 PM, Oleksandr Andrushchenko wrote:
>>> On 05/30/2018 06:54 PM, Boris Ostrovsky wrote:
>>>>
>>>> BTW, I also think you can further simplify
>>>> xenmem_reservation_va_mapping_* routines by bailing out right away if
>>>> xen_feature(XENFEAT_auto_translated_physmap). In fact, you might even
>>>> make them inlines, along the lines of
>>>>
>>>> inline void xenmem_reservation_va_mapping_reset(unsigned long count,
>>>>                       struct page **pages)
>>>> {
>>>> #ifdef CONFIG_XEN_HAVE_PVMMU
>>>>      if (!xen_feature(XENFEAT_auto_translated_physmap))
>>>>          __xenmem_reservation_va_mapping_reset(...)
>>>> #endif
>>>> }
>>> How about:
>>>
>>> #ifdef CONFIG_XEN_HAVE_PVMMU
>>> static inline __xenmem_reservation_va_mapping_reset(struct page *page)
>>> {
>>> [...]
>>> }
>>> #endif
>>>
>>> and
>>>
>>> void xenmem_reservation_va_mapping_reset(unsigned long count,
>>>                       struct page **pages)
>>> {
>>> #ifdef CONFIG_XEN_HAVE_PVMMU
>>>      if (!xen_feature(XENFEAT_auto_translated_physmap)) {
>>>          int i;
>>>
>>>          for (i = 0; i < count; i++)
>>>              __xenmem_reservation_va_mapping_reset(pages[i]);
>>>      }
>>> #endif
>>> }
>>>
>>> This way I can use __xenmem_reservation_va_mapping_reset(page);
>>> instead of xenmem_reservation_va_mapping_reset(1, &page);
>>
>> Sure, this also works.
> Could you please take look at the patch attached if this is what we want?
Please ignore it, it is ugly ;)
I have implemented this as you suggested:

static inline void
xenmem_reservation_va_mapping_update(unsigned long count,
                      struct page **pages,
                      xen_pfn_t *frames)
{
#ifdef CONFIG_XEN_HAVE_PVMMU
     if (!xen_feature(XENFEAT_auto_translated_physmap))
         __xenmem_reservation_va_mapping_update(count, pages, frames);
#endif
}

>> -boris
>>
> Thank you,
> Oleksandr