Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <69a5e350-ded9-30c9-dc41-d08c01dd05dc@intel.com>
Date:   Wed, 17 Aug 2022 08:43:57 -0700
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101
 Firefox/91.0 Thunderbird/91.12.0
Subject: Re: [PATCH 2/2] selftests/sgx: Add SGX selftest
 augment_via_eaccept_long
Content-Language: en-US
To:     Jarkko Sakkinen <jarkko@kernel.org>
CC:     "Dhanraj, Vijay" <vijay.dhanraj@intel.com>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        "linux-sgx@vger.kernel.org" <linux-sgx@vger.kernel.org>,
        Shuah Khan <shuah@kernel.org>,
        "open list:KERNEL SELFTEST FRAMEWORK" 
        <linux-kselftest@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
References: <20220815233900.11225-1-jarkko@kernel.org>
 <20220815233900.11225-2-jarkko@kernel.org>
 <6b304bb4-01cc-c88a-7299-19217a7a692b@intel.com>
 <YvwpX7pYOW3Jv+vJ@kernel.org>
 <DM8PR11MB55913534E8CE66F63460E707F66A9@DM8PR11MB5591.namprd11.prod.outlook.com>
 <24bd8e42-ff4e-0090-d9e1-cd81e4807f21@intel.com>
 <Yvz+yxnxp8G6KzHi@kernel.org> <Yv0A5vjd0OIfxxfT@kernel.org>
From:   Reinette Chatre <reinette.chatre@intel.com>
In-Reply-To: <Yv0A5vjd0OIfxxfT@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?elZ4ZUVMcDkvMEphb3BYYTFORnZBZVlLQk5FbnpyY1NqOFVmYVVSTWE5QWU0?=
 =?utf-8?B?UHllaThaV3NId0hGRSt0N0t5a1EvWitrSTBBaVhzbm5JWEtyTHlObHd5R0U1?=
 =?utf-8?B?emp4VUNnUXJOYkdjcEoyRGk4aFQ5QzZtZmpvZGNvQjRUS3l3SUlqbldRc2Zi?=
 =?utf-8?B?Wm5VQ0g4d0VLcTFxa0hSN1RYVEExQjEwOCtDZGRBMHBrZUZaejF5c3JEQllt?=
 =?utf-8?B?ZlRuNGI1WnNTcENYZXNGR0NMV2hXQS8wUFRSVnZXdVRtWG1lN200VmJRbUJw?=
 =?utf-8?B?aWRXMENZcWF5cnUzOUxCTGNuNlhNYkVzZUxnMFBpb0xOUUpDMDVMYUR5cjBC?=
 =?utf-8?B?cDhGMEVVT2dDQUlsV0t6WXdBSjEzUVBXT2VEMWtUSmhsL3c5M0djZU5RNjRz?=
 =?utf-8?B?Z0ZJOE4wSjcwdk5DV0xuZ1J6RU9qd2RuanVaem5DcUswU21NbzFwejVrM2M0?=
 =?utf-8?B?VmpYc3c5R1I4VlpGZUJPL2xyVE1uMFFMbWhxdHEwNHROYmRPYmZnVnZsRURV?=
 =?utf-8?B?WVU2MTdxKzg2YTM0dzVuUzFoc1ZmZE9SWXJkMTVLTUhsNVlPZG5yeEw0SHZM?=
 =?utf-8?B?UUprMFd6UkZHOHJXbWlraU1LODJINEpSaVJlYWxHVkczNk9CR1k4L0l6ellp?=
 =?utf-8?B?MlYyU3NTVFBKZFVWMVBZN3F2dEFDR1pzYW5oOWpscFBNWTZSWGZvb1hnOUdx?=
 =?utf-8?B?aW9TWkRVdVRaaXNMakJSdHh5QWR0Q2NqZTl1ZWFvQVVMdjhZVVYxbmZ6SFU2?=
 =?utf-8?B?Ky9jL055UWNxclFmdjZjQmNhN2plM0NQRC80SlI1TnRtbnVseUc0TWxheGwz?=
 =?utf-8?B?d2tBckl3TXpQZm1UaXRsb1d3YTRUTnpHa2E0aWJKVVdSZXZMeVhWbUlaNlJx?=
 =?utf-8?B?eTBBNEQ1cEVuMXlTdlJmdE1qN1VUMzRDTnMvMEFhM1MrM0tldG41bzh2bFhT?=
 =?utf-8?B?Qkx1SjhiTFZERHpJRVMzdGVJQVJGaUR0VnBoZHIvWjJNTnhDTGhHU3BMNVMr?=
 =?utf-8?B?dDYyVkNBYnBUb0orVXl2alhYNTVGd2l4OUZpVEJGaE9MMG1IeW1lblhMSktv?=
 =?utf-8?B?S3R3djUzSkRGaUJBeStNTyt1OXlsMTVmTzJDTnYyUEtqS2Z6WG9jemlGalpo?=
 =?utf-8?B?OVYyc3UxTElkVnZoLzhCNXlFZXVOMnJHeWsyUi9xdE85aEdlUmhuc0VESE5x?=
 =?utf-8?B?Tzdqa3ZWN3NHZmtRU1ZXbW5veFNzNjcrS3FaSE5nNDdzd3VQeWhlYmtiY1Iz?=
 =?utf-8?B?cC9lbW5DVlo3cGd5ekh1VVRMMEYxcmloR0VSU3JGclFGR1pNUktVUlV4RSs2?=
 =?utf-8?B?Y1Bwb01NTStZRzFNNW05WFgrUEJuak45ZlV2L1pmNXFiUVJFaFBjaCtIc3lV?=
 =?utf-8?B?Z2hDR2NGLy8rR0lRL2RTZUxTMkRCR2V2V0tkazUvbjAvU05tRXN4MHc2N3NI?=
 =?utf-8?B?RDJmUGdUMEpPODh0ZU5RNTFldTRoYTgyajRVaUIveERFcVFieUU4L09lVmZF?=
 =?utf-8?B?M1cvRXFNbVlIRHhKb3hMUnhBRTU2dUIxRnNBUENKMUxSZ1NqS2twRTlrbXdz?=
 =?utf-8?B?Z3VJa2U3RS9Lc2xwbHFFeHdBVVdYeDJHUUdteTRmcVBjbnBhaHBzQ2RNUTl5?=
 =?utf-8?B?VHdmVDhoUFJuR1ZjaForaEsxMlczNHhWbEx1OFNCMVRvV1N6T3NBNjlUOUlo?=
 =?utf-8?B?dmU3OVpUUmErbHROWlJqRDg2NDM2REUxalBVOUFwWFlNMExmUmFWaUpvd1c1?=
 =?utf-8?B?NXVHUUt3UUd1blRJQnY2YTRvTlZnenFqdGtEcmpCWFR1bDZMK0R4K3lRQWNN?=
 =?utf-8?B?YVdjUkt4akp4bVJlRFQ4VFR6SWJ1VUM3VEtSSUwzc1BFU0xxZVRUcmk4SFRn?=
 =?utf-8?B?VjRCSnNhQjQyRlFkRnFKWGpoVDBoYWErM3Bib1NSdmErb0t5cHNkc0NJR1lt?=
 =?utf-8?B?czMrRFhEdUJqM0dHNDNUcmFZRWlsYVh3clR1emMyQWdiK3ZEb3J1eXFBa1Mv?=
 =?utf-8?B?RElYbDZlWXh5V3RKdTBHeXN3bU4zeWZxOUxDOEt2dGNtSkdERzVRa0dGQWY3?=
 =?utf-8?B?anNTb2JmN0hLNENHQWNFTHRMTlVxR25wWGdwWlc3YXU3ZDJ1SW1UMHhURjFC?=
 =?utf-8?B?L09hVW82b3dtaXZ1czBrOXJGU2M1L1pWTDZMbUZNQ0ZzOHc3S2txTHN0MmhY?=
 =?utf-8?B?eFE9PQ==?=
X-MS-Exchange-CrossTenant-Network-Message-Id: 0e92c12a-b02d-4a25-b1a2-08da80674de2
X-MS-Exchange-CrossTenant-AuthSource: CY4PR11MB1862.namprd11.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 17 Aug 2022 15:44:00.4285
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 46c98d88-e344-4ed4-8496-4ed7712e255d
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: MKCLKTq8ilmJN3oqpcibKNphBDJxMDoEccDxfxUiUrhJ/HTx9KYfGHy1pY3CW6rxa7PRKEl5HFmGg2ZRidVhOia/6pbLrjWBhc0VEHkp8Ck=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BN7PR11MB2866
X-OriginatorOrg: intel.com
X-Spam-Status: No, score=-4.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,
        DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,
        RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE,
        URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.6
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on
        lindbergh.monkeyblade.net
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Hi Jarkko,

On 8/17/2022 7:53 AM, Jarkko Sakkinen wrote:
> On Wed, Aug 17, 2022 at 05:44:31PM +0300, Jarkko Sakkinen wrote:
>> On Tue, Aug 16, 2022 at 09:35:27PM -0700, Reinette Chatre wrote:
>>>>>> This portion below was also copied from previous test and by only
>>>>>> testing a write to the first page of the range the purpose is not
>>>>>> clear. Could you please elaborate if the intention is to only test
>>>>>> accessibility of the first page and why that is sufficient?
>>>>>
>>>>> It is sufficient because the test reproduces the bug. It would have to be
>>>>> rather elaborated why you would possibly want to do more than that.
>>>
>>> That is fair. An accurate comment (currently an inaccurate copy&paste) would
>>> help to explain this part of the test.
>>
>> I would simply add something like:
>>
>> /* 
>>  * Define memory pool size big enough to trigger the reclaimer in the EAUG
>>  * path of the page reclaimer.
>>  */
>>
>> Suggestions/edits obviously welcome for the comment.

The comment seems to better match the code below than the area referred to above:
        static const unsigned long edmm_size = 8589934592; //8G

Even so, I think that raises the point that this is platform specific since
edmm_size of 8GB would not trigger reclaimer on all platforms.

How about adjusting it to:
/*
 * Define memory pool size big enough to trigger the reclaimer in the EAUG
 * path of the page reclaimer on some platforms. This constant has been
 * successful in triggering a bug on some platforms (independent of the
 * platforms where the reclaimer is triggered) and thus considered
 * appropriate for general use.
 */ 


Regarding the area referred to above, a comment like below may help:

/*
 * Pool of pages were successfully added to enclave. Perform sanity
 * check on first page of the pool only to ensure data can be written
 * to and read from a dynamically added enclave page.
 */

> 
> I wonder if we could put .bt files somewhere to make them available. In
> root causing this bug bpftrace scripting was the key so it would nice to
> have them available along with kselftest.
> 
> I could imagine that we end up also in future to bugs allocation so
> it would have the script when you clone the kernel tree, and possibly
> more scripts in future.
> 
> E.g. add bt/alloc-error.bt under tools/testing/selftests/sgx.

Thank you very much for helping to debug this issue. I also think
the scripts you created are very valuable and making them easily
accessible sounds great.

Reinette