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;
From:   Eric DeVolder <eric.devolder@oracle.com>
To:     linux-kernel@vger.kernel.org, x86@kernel.org,
        kexec@lists.infradead.org, ebiederm@xmission.com,
        dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com
Cc:     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, david@redhat.com,
        sourabhjain@linux.ibm.com, konrad.wilk@oracle.com,
        boris.ostrovsky@oracle.com, eric.devolder@oracle.com
Subject: [PATCH v11 5/7] kexec: exclude hot remove cpu from elfcorehdr notes
Date:   Fri, 26 Aug 2022 13:37:02 -0400
Message-Id: <20220826173704.1895-6-eric.devolder@oracle.com>
In-Reply-To: <20220826173704.1895-1-eric.devolder@oracle.com>
References: <20220826173704.1895-1-eric.devolder@oracle.com>
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?pWdSWKpzZ4Wul7MEjDvIO3exqrcnRTeN7TA+yNUZ4HCFQoPDUlIyNH9nbFxg?=
 =?us-ascii?Q?9Mh0HjPHAY5GzMClBfoVqix7wAf2bISM2/JJajqW9xokeJlUU2Qhq6HonS8f?=
 =?us-ascii?Q?ddg67VVKG+aTvWj4atZxYAdmlOEmkop4fAKYEtQMcBgObTbKgZ51K0h3DQrJ?=
 =?us-ascii?Q?8n2k+T3O21J0qUFDW8IMQv4SQIC663U5pLjE6DIHQtnVFwZoz4Ao3nwdp1SU?=
 =?us-ascii?Q?K7Ne9q0GlJXy9emzxmvRBMniOESkt68Y5S+2+DpUfJquk5IlDsbhK3qSPDFU?=
 =?us-ascii?Q?NU8F712p4qj7LWk/cjeMd1yaM+IS1hDiNSr6IqRfQ2m0BVmH+qAB+53JOB/F?=
 =?us-ascii?Q?uXAd+A8uREjN47uO2XMUypi7i11f0PA+tPOps3/+55udIhYlB+/56zky6Lfi?=
 =?us-ascii?Q?bv1qhoxWH5tMX2VNKrLQoZmiyY6xka9TQ0xeT71VtzVCK+Tls1W/reEQd21L?=
 =?us-ascii?Q?24WDVIClhYLEIBOEtgGRhUQN5BUHzdMhqRCx3k0VW7wmJ+5/vcqMwRyySKt/?=
 =?us-ascii?Q?wEXRPD5AbH7hXesDJuGaDEH5B+sFm5aOXlhk5HjtAJii55c1xI40911QWZW3?=
 =?us-ascii?Q?uUk3PJjxY9HTjpDyTCdCPff8hFN64IRBPSBbtONPpPV5AbPFZLG6N7vl/R12?=
 =?us-ascii?Q?2bzCvDer0ZEW7yCBKW0Jeso9ahgBEJ6chiKhz8T6kmaJj85G3bnwCARzYbX7?=
 =?us-ascii?Q?MiOXnsiIvwMKeiZ/4A6EHVSc3p5hihfEATcBFiQnUjDRNkuMntMMt4UaO6qs?=
 =?us-ascii?Q?v7uYtzrd3wO9kby2sVYeHdmmUfrVca5lwWwejdDI9gB87HfeVNReW0FNTwkc?=
 =?us-ascii?Q?ACCUnsSeIeGyJ9LsZa2EoI2F70isn8bXtx/zy5CCUkfvmM1ttzpc9AmpC20P?=
 =?us-ascii?Q?uRvEil6OPg4aP+XqOqG/KqerzpZS2TUv2zGGPh6+iIfzG5j8UszkXzqz7w8t?=
 =?us-ascii?Q?XN+H5Lti328doWskE4sTmMgVdcdBvRD6n//iBjqoah0GfDNvexdIlmC4XTbd?=
 =?us-ascii?Q?pGAQJPM3aJNzmbqHUIFBZv66rhwccsKfdgcz0JbwqrPbkcNvdC9hw0ldxcXl?=
 =?us-ascii?Q?ehWpjf3kwJqWnVDLl5KBEMmdw1N5yjWEgSngcm84muBoA9+X8CR8lfazHJMZ?=
 =?us-ascii?Q?bEEsZbjgEo4URXWNB3irt2QRFXfto9WP7ZowiQ0BOb5ssEOEuPbBU/t4Vd3i?=
 =?us-ascii?Q?vczUTn8uJg3VfsSnhXOdydHiv6v5z7zB6UDyO0G1kUUkSp2VijwsTJiokvs0?=
 =?us-ascii?Q?1HBp+wv15xMVlmWLTuROGjBdSXb+C7LWZWC78LgvA0YIHRrLBiSwefBe2i5M?=
 =?us-ascii?Q?jyoHI/VU2fujm7fR48XR8NJktPhChGFSsLPr3mx74AsGimURpvreeHv9QPk9?=
 =?us-ascii?Q?nkeqR/G+aM4KMQQ4dfuaW449jtYzxLePPFluPXHbBgoxUnQpv0iENZQypb60?=
 =?us-ascii?Q?ZH34zwVeBhuMt0ep1QG+ZiGuM1m3irFJOrnkheAQg0VwWcu08KkK6WUp86fc?=
 =?us-ascii?Q?ITPpr8i70bVAEP0piQlE+U6ctWZ30gxjRpBu8Fjo43HaADR3Er33e9hgMaMM?=
 =?us-ascii?Q?tNJ3Gw9lhAkvAEr3Mp7NTWvWzb8qaPdMNRj3ZE9cdvX6jmOJn6hqRsnULOH0?=
 =?us-ascii?Q?tw=3D=3D?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 08bdbe8e-539b-4bc9-0b21-08da8789a18c
X-MS-Exchange-CrossTenant-AuthSource: CO1PR10MB4531.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 26 Aug 2022 17:37:21.8644
 (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: s630yDGSY7J0pHzZYFwiwskVfy5qh/JpEO+fsJuma8oAnGHijVAkvLDVH8LwVRpYw+HV9OfMGeP3qVyE5WFzOcuIUNIdqQ8bqpfsU9IsWcE=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR10MB6231
X-Proofpoint-Virus-Version: vendor=baseguard
 engine=ICAP:2.0.205,Aquarius:18.0.895,Hydra:6.0.517,FMLib:17.11.122.1
 definitions=2022-08-26_10,2022-08-25_01,2022-06-22_01
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 spamscore=0 mlxlogscore=999
 phishscore=0 adultscore=0 mlxscore=0 bulkscore=0 suspectscore=0
 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1
 engine=8.12.0-2207270000 definitions=main-2208260070
X-Proofpoint-ORIG-GUID: 66RU685OCkcjErD3CnqXAVxh6Bix4rgD
X-Proofpoint-GUID: 66RU685OCkcjErD3CnqXAVxh6Bix4rgD
X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,
        DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,
        RCVD_IN_MSPIKE_H2,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

Due to use of CPUHP_AP_ONLINE_DYN, upon CPU unplug, the CPU is
still in the for_each_present_cpu() list when within the
handle_hotplug_event(). Thus the CPU must be explicitly excluded
when building the new list of CPUs.

This change identifies in handle_hotplug_event() the CPU to be
excluded, and the check for excluding the CPU in
crash_prepare_elf64_headers().

Signed-off-by: Eric DeVolder <eric.devolder@oracle.com>
Acked-by: Baoquan He <bhe@redhat.com>
---
 kernel/crash_core.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 455150205ded..2f84a221b370 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -366,6 +366,11 @@ int crash_prepare_elf64_headers(struct kimage *image, struct crash_mem *mem,
 
 	/* Prepare one phdr of type PT_NOTE for each present CPU */
 	for_each_present_cpu(cpu) {
+#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG)
+		/* Skip the soon-to-be offlined cpu */
+		if (image->hotplug_event && (cpu == image->offlinecpu))
+			continue;
+#endif
 		phdr->p_type = PT_NOTE;
 		notes_addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpu));
 		phdr->p_offset = phdr->p_paddr = notes_addr;
@@ -681,6 +686,16 @@ static void handle_hotplug_event(unsigned int hp_action, unsigned int cpu)
 		/* Flag to differentiate between normal load and hotplug */
 		image->hotplug_event = true;
 
+		/*
+		 * Due to use of CPUHP_AP_ONLINE_DYN, upon unplug and during
+		 * this callback, the CPU is still in the for_each_present_cpu()
+		 * list. Must explicitly look to exclude this CPU when building
+		 * new list.
+		 */
+		image->offlinecpu =
+			(hp_action == KEXEC_CRASH_HP_REMOVE_CPU) ?
+				cpu : KEXEC_CRASH_HP_INVALID_CPU;
+
 		/* Now invoke arch-specific update handler */
 		arch_crash_handle_hotplug_event(image, hp_action);
 
-- 
2.31.1