Message-ID: <192e252a-653f-2221-73dd-99894c134a37@intel.com>
Date:   Mon, 13 Dec 2021 14:11:26 -0800
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Subject: Re: [PATCH 07/25] x86/sgx: Move PTE zap code to separate function
Content-Language: en-US
To:     Jarkko Sakkinen <jarkko@kernel.org>
CC:     <dave.hansen@linux.intel.com>, <tglx@linutronix.de>,
        <bp@alien8.de>, <luto@kernel.org>, <mingo@redhat.com>,
        <linux-sgx@vger.kernel.org>, <x86@kernel.org>, <seanjc@google.com>,
        <kai.huang@intel.com>, <cathy.zhang@intel.com>,
        <cedric.xing@intel.com>, <haitao.huang@intel.com>,
        <mark.shanahan@intel.com>, <hpa@zytor.com>,
        <linux-kernel@vger.kernel.org>
References: <cover.1638381245.git.reinette.chatre@intel.com>
 <bd228c90c139437bb4fcc4b7b99063bfd3eb1439.1638381245.git.reinette.chatre@intel.com>
 <Yavy5JTYAkdZjnK2@iki.fi> <66151f3a-0e32-fc57-cb54-5b714588389b@intel.com>
 <917c53ff755d9a20e1f4bcb48c70add8364d1065.camel@kernel.org>
From:   Reinette Chatre <reinette.chatre@intel.com>
In-Reply-To: <917c53ff755d9a20e1f4bcb48c70add8364d1065.camel@kernel.org>
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Hi Jarkko,

On 12/10/2021 11:52 PM, Jarkko Sakkinen wrote:
> On Mon, 2021-12-06 at 13:30 -0800, Reinette Chatre wrote:
>> Hi Jarkko,
>>
>> On 12/4/2021 2:59 PM, Jarkko Sakkinen wrote:
>>> On Wed, Dec 01, 2021 at 11:23:05AM -0800, Reinette Chatre wrote:
>>>> The SGX reclaimer removes page table entries pointing to pages that are
>>>> moved to swap. SGX2 enables changes to pages belonging to an initialized
>>>> enclave, for example changing page permissions. Supporting SGX2 requires
>>>> this ability to remove page table entries that is available in the
>>>> SGX reclaimer code.
>>>
>>> Missing: why SGX2 requirest this?
>>
>> The above paragraph states that SGX2 needs to remove page table entries
>> because it modifies page permissions. Could you please elaborate what is
>> missing?
> 
> It does not say why SGX2 requires an ability to remove page table entries.

Are you saying that modification of EPCM page permissions is not a 
reason to remove page table entries pointing to those pages?

Reinette