linux-kernel - Re: [PATCH v3 4/9] xen/grant-table: Allow allocating buffers suitable for DMA

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Message-ID: <ffd6eb5a-b057-8cca-c8cb-75fd97b63a45@gmail.com>
Date:   Wed, 13 Jun 2018 10:07:58 +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 v3 4/9] xen/grant-table: Allow allocating buffers suitable
 for DMA

On 06/13/2018 04:12 AM, Boris Ostrovsky wrote:
>
>
> On 06/12/2018 09:41 AM, Oleksandr Andrushchenko wrote:
>> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
>>
>> Extend grant table module API to allow allocating buffers that can
>> be used for DMA operations and mapping foreign grant references
>> on top of those.
>> The resulting buffer is similar to the one allocated by the balloon
>> driver in terms that proper memory reservation is made
>> ({increase|decrease}_reservation and VA mappings updated if needed).
>> This is useful for sharing foreign buffers with HW drivers which
>> cannot work with scattered buffers provided by the balloon driver,
>> but require DMAable memory instead.
>>
>> Signed-off-by: Oleksandr Andrushchenko 
>> <oleksandr_andrushchenko@...m.com>
>
> Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
>
> with a small nit below
>
>
>> ---
>>   drivers/xen/Kconfig       | 13 ++++++
>>   drivers/xen/grant-table.c | 97 +++++++++++++++++++++++++++++++++++++++
>>   include/xen/grant_table.h | 18 ++++++++
>>   3 files changed, 128 insertions(+)
>>
>> diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
>> index e5d0c28372ea..39536ddfbce4 100644
>> --- a/drivers/xen/Kconfig
>> +++ b/drivers/xen/Kconfig
>> @@ -161,6 +161,19 @@ config XEN_GRANT_DEV_ALLOC
>>         to other domains. This can be used to implement frontend drivers
>>         or as part of an inter-domain shared memory channel.
>>   +config XEN_GRANT_DMA_ALLOC
>> +    bool "Allow allocating DMA capable buffers with grant reference 
>> module"
>> +    depends on XEN && HAS_DMA
>> +    help
>> +      Extends grant table module API to allow allocating DMA capable
>> +      buffers and mapping foreign grant references on top of it.
>> +      The resulting buffer is similar to one allocated by the balloon
>> +      driver in terms that proper memory reservation is made
>> +      ({increase|decrease}_reservation and VA mappings updated if 
>> needed).
>
> I think you should drop the word "terms" and say "is made *by*" and 
> "VA mappings *are* updated"
>
> And similar change in the commit message.
>
Will, change, thank you
> -boris
>