linux-kernel - Re: [PATCH V3 19/30] x86/sgx: Free up EPC pages directly to support large page ranges

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Message-ID: <96d630b3-c2df-99d5-e057-6787bd107d09@intel.com>
Date:   Tue, 5 Apr 2022 12:56:03 -0700
From:   Reinette Chatre <reinette.chatre@...el.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>
CC:     <dave.hansen@...ux.intel.com>, <tglx@...utronix.de>,
        <bp@...en8.de>, <luto@...nel.org>, <mingo@...hat.com>,
        <linux-sgx@...r.kernel.org>, <x86@...nel.org>, <seanjc@...gle.com>,
        <kai.huang@...el.com>, <cathy.zhang@...el.com>,
        <cedric.xing@...el.com>, <haitao.huang@...el.com>,
        <mark.shanahan@...el.com>, <hpa@...or.com>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH V3 19/30] x86/sgx: Free up EPC pages directly to support
 large page ranges

Hi Jarkko,

On 4/5/2022 11:42 AM, Jarkko Sakkinen wrote:
> On Tue, 2022-04-05 at 10:13 -0700, Reinette Chatre wrote:
>> On 4/5/2022 12:11 AM, Jarkko Sakkinen wrote:
>>> On Mon, Apr 04, 2022 at 09:49:27AM -0700, Reinette Chatre wrote:

...

>>>> diff --git a/arch/x86/kernel/cpu/sgx/main.c b/arch/x86/kernel/cpu/sgx/main.c
>>>> index 6e2cb7564080..545da16bb3ea 100644
>>>> --- a/arch/x86/kernel/cpu/sgx/main.c
>>>> +++ b/arch/x86/kernel/cpu/sgx/main.c
>>>> @@ -370,6 +370,12 @@ static bool sgx_should_reclaim(unsigned long watermark)
>>>>                !list_empty(&sgx_active_page_list);
>>>>  }
>>>>  
>>>> +void sgx_direct_reclaim(void)
>>>> +{
>>>> +       if (sgx_should_reclaim(SGX_NR_LOW_PAGES))
>>>> +               sgx_reclaim_pages();
>>>> +}
>>>
>>> Please, instead open code this to both locations - not enough redundancy
>>> to be worth of new function. Causes only unnecessary cross-referencing
>>> when maintaining. Otherwise, I agree with the idea.
>>>
>>
>> hmmm, that means the heart of the reclaimer (sgx_reclaim_pages()) would be
>> made available for direct use from everywhere in the driver. I will look into this.
>>
>> Reinette
>>
> 
> It's a valid enough point. Let's keep it as it is :-)

Will do. I plan to add Dave's suggested comments to sgx_direct_reclaim() that is
introduced in this patch.

> 
> Acked-by: Jarkko Sakkinen <jarkko@...nel.org>

Thank you very much.

Reinette