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: <10d67f14-c5fe-0a17-e8b5-97702823cc1c@oracle.com>
Date:   Tue, 1 Mar 2022 14:04:08 -0600
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Thunderbird/91.3.1
Subject: Re: [PATCH v4 02/10] crash hp: Introduce CRASH_HOTPLUG configuration
 options
Content-Language: en-US
To:     Baoquan He <bhe@redhat.com>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        kexec@lists.infradead.org, ebiederm@xmission.com,
        dyoung@redhat.com, vgoyal@redhat.com, tglx@linutronix.de,
        mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
        hpa@zytor.com, nramas@linux.microsoft.com, thomas.lendacky@amd.com,
        robh@kernel.org, efault@gmx.de, rppt@kernel.org,
        konrad.wilk@oracle.com, boris.ostrovsky@oracle.com
References: <20220209195706.51522-1-eric.devolder@oracle.com>
 <20220209195706.51522-3-eric.devolder@oracle.com>
 <YhWpF/Cj/V+Cx6+d@MiWiFi-R3L-srv>
From:   Eric DeVolder <eric.devolder@oracle.com>
In-Reply-To: <YhWpF/Cj/V+Cx6+d@MiWiFi-R3L-srv>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?Tk9GaXd3a2NFLy9kSEFybzgrYkszUGxONzM1cVFqSVlSMVE0ZFNsQjEwMlky?=
 =?utf-8?B?bGx1RVRDU0xIMUJMNnhCYUpKaW1oc1VwYit5a2ZDZHFIR0xRYzRtVkZCQU01?=
 =?utf-8?B?cTByMnVkVm5XVC9SdWl3RXg3ZFJtNHRHNHkvZUtUNnpXOHdEUWFyb2JjNk1i?=
 =?utf-8?B?ZzAwYloxOVRRYTlFUmlhWVlubHFUWnRQYW1UTFRxVFd4bDd2WWRUOTdhck5w?=
 =?utf-8?B?d0tUMXE5ekVGSXNMUVh3K3FqZFMyMjVqcTh5QVEvdFRnV2NBQjFhbzhYQ3RL?=
 =?utf-8?B?b3BIaEZFTXNuQkoxbC9ydVM0dVpFdVViVGp0ZWJrS3BScmRkbWE4ZDRHQ0p5?=
 =?utf-8?B?VGdtaUx2M1M5UDVicWNnazhzQlo4aHUrSW5WTTlpNHdXOUlaN1pxanIyUGIx?=
 =?utf-8?B?TjFPZXVTaTdqK0FvTWVDeEUwdXNjVmhrT1lPTm9CN2svSFRub3ZCbnRoRkMz?=
 =?utf-8?B?TEh3TnFJckJ2MW9VbEQxZGJmZWZLNTNmL0RybVVIRXQ5dVdwVE9sejJHejlk?=
 =?utf-8?B?M2QwNE45Qk1jMFRrOGxkNmNibk5SWjMvb0tJRGNYdVRoVUJUNkIwMXRDZWc1?=
 =?utf-8?B?Nzk2ZUo0WXdvNHAxT2VNYXlZd2NraGZUSExMaVF2Tnc3YTRiK1NMaGZFMVhQ?=
 =?utf-8?B?Z2lkWjdXMlZaMkxpaVp5M0dET2NwTUNoQnNzaHpCL1R4YThteW1tQ3kraHQr?=
 =?utf-8?B?L1c1ZGF1OWRGUXZzdmdzRGhKSVh1V3BTL2Nzc25tTDZld0hwK2UwT1VGYTNB?=
 =?utf-8?B?bjBncTRvV2FGWk4zaWtvWklIeFh5UlMvSUJ4dVY5QWVsUWpDT2hsZXhDdzdy?=
 =?utf-8?B?bERzTXMzZk56YTl5OUVMZWU4WExmZkoxUkEyeGI3ejNsNTNxa0xhb29iblM0?=
 =?utf-8?B?VURFd2V1dHFJY3BHeW9LRUVlK2lhWjl0eENBMWVKZFJmU0lKVHMwZ0VFUXky?=
 =?utf-8?B?YitISGF3VG1ia2hBd2M5ZVY2TVpKRHQyWncwZkQ4dWNkb3hNQXlKd29WN0d2?=
 =?utf-8?B?MjJIL3hwVFg3bEp3c3hMRm9PRFA4ejFuZjBLVzJ4dVhZZFpiNTFMbm1mMElz?=
 =?utf-8?B?SmJoZi83RHl2K2xCQkZIWjJmK0FqdVd0S3dtMy9CNmVrZlBhTHFiT1dkS3lE?=
 =?utf-8?B?ci82YnlUbWdJNlZBUlU4QnM0eE81ZlhvT202YTFSOVNaR0t2a0FQWDFRa3VW?=
 =?utf-8?B?eG1kMkxLN3g2UW91d1BCc3V3Y0JTbjU0RUpyVTdOcERmS1dSS3ZKYVE2ZFBI?=
 =?utf-8?B?LzFxM2NXa2o5ZFRTU2hiTXRMRUg2a3drQmtUTTFpN0lhV1FBTFl4TEJDaFhi?=
 =?utf-8?B?Vmh4b1RiRDdVb2xPcWpHLzhEYno2Q1dVcUpabnFFTlNMRVRFamQyZWtxWTc4?=
 =?utf-8?B?T1VXZFByb1FsdE1NbFdrZCsxMlUyNmFlcklZenN1cFpQY2E4Y0c1OXJvaGQz?=
 =?utf-8?B?YkpRemlwYXFGZlF1SllyeGkxQ0NuSm5vdVFaWGVvRTBkMlVFOS9scE5hcDZG?=
 =?utf-8?B?SDVtM085ZmtMOFYyMmhXUHlTRGNDYnBpRTltcmlZN1Avb0l3TWZEcElKbkNt?=
 =?utf-8?B?VEEzdmZJcVpVWW9qVHoyYUNHb1hQRlREL09OMkVpT3UxdnA3elZ6M3dTMUdS?=
 =?utf-8?B?VGtPaDFrU0p5Y294VXZjZzVMTG1jOC9xdzFNbDNqVnV0VG1MbXFRTmxxQ3o3?=
 =?utf-8?B?WW9DeEdBNWVxYjJxQktlQmtOUDloeWc3eHdYN0hxdVhyZmJBRWtPVHZPSklx?=
 =?utf-8?B?cFhBcDJLRllsQ0UrQ2wzY2I4eHMvTlI5Ny9UcWNYK0JtK3JDclNFcXhVdlNq?=
 =?utf-8?B?U3NtOFh1bmt6WGdHQmgyVlBTUDREM3AwbDdYUVZRVDNQMnh6QTQ4MFFZNlhx?=
 =?utf-8?B?QWsxL1R1QzFpMFdVV0FZakU5MzZ3RmFDbHFaNU5KemtoOWpwbUJ0US9GSnV2?=
 =?utf-8?B?ZUxYT2JqQ1hkY09CVzMrL1daZW1LNXp2RWFEZmxjUFIyRlY3QzM3b1pQdTQ3?=
 =?utf-8?B?NUo4Wmt2Zmh0R2FOMURsRE1VK0NJaVNVdVlSK21kY2tPY0VEQkJyNTVzMUR5?=
 =?utf-8?B?RTBFYUZIMHV1WWZzcXc0elF6ckxlczNacHgxYXd6dXo2b0tqUTF0MTZJMlBV?=
 =?utf-8?B?ZW5ZZW5WRTY2UUxYV2oxblZmNXVLbmsxRmxTeTJ5clRiUmxlQmxoTHdKa0ZF?=
 =?utf-8?B?OFhoQnkrU2tLZDZkY0lHSGJaeUdoeTVJSzRDUVpXYmdmK20wSXptVEsxa0Y4?=
 =?utf-8?B?SkxmTzJDdmdRL25lZE1kS2gwV1NaaFZrcGJoVHZnODNsL0I4SVBnVlVVb0kr?=
 =?utf-8?Q?pinxywOIuGnSAXMDv5?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 927eeb44-8c48-4a08-8902-08d9fbbea784
X-MS-Exchange-CrossTenant-AuthSource: SJ0PR10MB4542.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 01 Mar 2022 20:04:12.4974
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: cdI6RQit6f5gw0EP72TLiRmJo8KXd1GsDXkFBSZzRn6lu38KSVTcrz9acxHRP/r+C4qMSTVQ+aX5I7y1qjHr/efUyqjj1esdSjuLivQVJvE=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BLAPR10MB5298
X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10273 signatures=685966
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxlogscore=999 bulkscore=0
 adultscore=0 phishscore=0 spamscore=0 suspectscore=0 malwarescore=0
 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1
 engine=8.12.0-2201110000 definitions=main-2203010100
X-Proofpoint-ORIG-GUID: WlyBY7BMTfmxlq1u-7IQOUX_ZdxCdUYS
X-Proofpoint-GUID: WlyBY7BMTfmxlq1u-7IQOUX_ZdxCdUYS
X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,NICE_REPLY_A,RCVD_IN_DNSWL_LOW,
        RCVD_IN_MSPIKE_H5,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE,
        T_SCC_BODY_TEXT_LINE 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


On 2/22/22 21:25, Baoquan He wrote:
> On 02/09/22 at 02:56pm, Eric DeVolder wrote:
>> Support for CPU and memory hotplug for crash is controlled by the
>> CRASH_HOTPLUG configuration option, introduced by this patch.
>>
>> The CRASH_HOTPLUG_ELFCOREHDR_SZ related configuration option is
>> also introduced with this patch.
>>
>> Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
>> ---
>>   arch/x86/Kconfig | 26 ++++++++++++++++++++++++++
>>   1 file changed, 26 insertions(+)
>>
>> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
>> index ebe8fc76949a..4e3374edab02 100644
>> --- a/arch/x86/Kconfig
>> +++ b/arch/x86/Kconfig
>> @@ -2060,6 +2060,32 @@ config CRASH_DUMP
>>   	  (CONFIG_RELOCATABLE=y).
>>   	  For more details see Documentation/admin-guide/kdump/kdump.rst
>>   
>> +config CRASH_HOTPLUG
>> +	bool "kernel updates of crash elfcorehdr"
>> +	depends on CRASH_DUMP && (HOTPLUG_CPU || MEMORY_HOTPLUG) && KEXEC_FILE
>> +	help
>> +	  Enable the kernel to update the crash elfcorehdr (which contains
>> +	  the list of CPUs and memory regions) directly when hot plug/unplug
>> +	  of CPUs or memory. Otherwise userspace must monitor these hot
>> +	  plug/unplug change notifications via udev in order to
>> +	  unload-then-reload the crash kernel so that the list of CPUs and
>> +	  memory regions is kept up-to-date. Note that the udev CPU and
>> +	  memory change notifications still occur (however, userspace is not
>> +	  required to monitor for crash dump purposes).
>> +
>> +config CRASH_HOTPLUG_ELFCOREHDR_SZ
>> +	depends on CRASH_HOTPLUG
>> +	int
>> +	default 131072
>> +	help
>> +	  Specify the maximum size of the elfcorehdr buffer/segment.
>> +	  The 128KiB default is sized so that it can accommodate 2048
>> +	  Elf64_Phdr, where each Phdr represents either a CPU or a
>> +	  region of memory.
>> +	  For example, this size can accommodate hotplugging a machine
>> +	  with up to 1024 CPUs and up to 1024 memory regions (e.g. 1TiB
>> +	  with 1024 1GiB memory DIMMs).
> 
> This example of memory could be a little misleading. The memory regions
> may not be related to memory DIMMs. System could split them into many
> smaller regions during bootup.

I changed "with 1024 1GiB memory DIMMs" to "with 1024 1GiB hotplug memories".
eric

> 
> Otherwise, this patch looks good to me.
> 
>> +
>>   config KEXEC_JUMP
>>   	bool "kexec jump"
>>   	depends on KEXEC && HIBERNATION
>> -- 
>> 2.27.0
>>
>