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 v10 6/8] kexec: exclude hot remove cpu from elfcorehdr notes
Date:   Thu, 21 Jul 2022 14:17:45 -0400
Message-Id: <20220721181747.1640-7-eric.devolder@oracle.com>
In-Reply-To: <20220721181747.1640-1-eric.devolder@oracle.com>
References: <20220721181747.1640-1-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?RloSTocCfCMWlXvJI+hHKOXiBY/eIkST1Baw6yAI2t/898m5x/OLjyw5EqCp?=
 =?us-ascii?Q?zlDArWsuoLFN16uXVSb/bH33lmx7gnnfO8uSATX8ga/jLn+EIuBL9eHIXclI?=
 =?us-ascii?Q?lxoaSsdcTCXNOcom5Kh87OBp3M5XnTYnwY2/ClHIzPcCKbqTnVGXRq64S7QG?=
 =?us-ascii?Q?NWujK5t+4K3I8uxuLcdVVqH4jQXe4UWDQ8Dfyi9cIFGnhBb5gIibzR9+4NI/?=
 =?us-ascii?Q?f/MqJ2VvaA9dbPtBYegQiqN+33xSEtCH1AgP2vFFqV8iK2VGo1+zdu9Vjlzr?=
 =?us-ascii?Q?q3EB5OesAB367oTMiXPzv99xcc8ZyHfKlq+bczxE1rybwcOQ2aayKlQ1OXbw?=
 =?us-ascii?Q?16GYx1Bk65F6lwr4L0hh8ahVVO+LjH4SbDZb4e6q2Ladjayq0JevwknZnBYC?=
 =?us-ascii?Q?ok0rfRsUa3EZllHmj0da+1y2lLVPt5Btn9Px3h5eDfrSDweaxUZnfL0W5TL1?=
 =?us-ascii?Q?rH19JYdNYvmLOliJ9a6kU+ryPk9s0yuAhIOy01ZjRLUTOKW6k/sbzF6NZocb?=
 =?us-ascii?Q?7GsokQOfHE/PLN0objQ7D5mTEPkraITGpNwSprHEBli91Xsush1au9jX3q4G?=
 =?us-ascii?Q?yrOLttG5lQyphky347uN+APTmOKSYCc+KeEMfCRvfbUYak/WgHOaviWIyvgu?=
 =?us-ascii?Q?tN8uMTuV9VUJD26tVgXmjp0QOtzDQ4sGACinmqga4g1he48Qorc/exZLmcL/?=
 =?us-ascii?Q?HrLcr1JdUHkyckxyE5GZIxKX8xOIxskeOdjJ75D2nLwHQBwFP2rEl5P3OFqc?=
 =?us-ascii?Q?m63Hmyc2jdi+6mi6bixSaUJwCej8SlPmUtWWbrt22aINZj2FxlCMHghw/nbA?=
 =?us-ascii?Q?/vDkucto5jLWvpXiZ2mB+PeccJ93eaLzi5Xty0nHMhTX2Nr5fYnyubjmRWRx?=
 =?us-ascii?Q?b0vuab+cchBeC3W6Ib2r/+D8g4NRP62DntfY3mSbJlwXxrgNCuV1CvepkMok?=
 =?us-ascii?Q?nF1tMRjMKFJ8DaCqr/s7AyPmUcFY8t9nTaHSet9RCLGjrKjexfst4khNdMNt?=
 =?us-ascii?Q?djBWClSIHdkIQv69Io/8cEAmTXYXr6zl4Nt4foei5Ub7z6sBDZkkG88uFi9J?=
 =?us-ascii?Q?t8AOezlQsmMEDH2LkzusSWbliBjrILhWUf/EZA8uH+FIS/7ammP9SSgoSrhj?=
 =?us-ascii?Q?LP7ddPrnS1GOAT+lVz8E0pBAXhj7zXMqwbbtpDZEsXqBCnIx/t7t2ipb2Sh/?=
 =?us-ascii?Q?V3mG/owHTgFH6inJ73VjQnanHtAb4TXDLvWCrayaKtlGexrpYHTUgMVO8UsN?=
 =?us-ascii?Q?7EzxHtdpdjquo/yk7Zowq+MGJLBwRHX6x94ezFerihhfXUqVdOGCG6AW4FuL?=
 =?us-ascii?Q?9zJks6/pHIlq57zMMIWRo/BCYy92R6pXso0tb+VpzVCKvJOfHEEIVAB+046O?=
 =?us-ascii?Q?QZdInB5YLy2N1C4BqAbEbdvaiekqVy0BJ1146NdyfcMnObnvpEnXSPZ/f7zi?=
 =?us-ascii?Q?PwdGfUEuzSybgPIWmCkob6AP1hweUmq6mzk9Tm/Y8iNae31hdUdyPFk8c8hV?=
 =?us-ascii?Q?0Q8zzaaWmGCMMyxEdKBCmSgc0czrJvqJXxLGKRz6uDdxubvXBiKrXqlrNeLh?=
 =?us-ascii?Q?c25Dsv6ZEUWj3REGTQv1GtQiqavrkkZrhcAVX9VOjYhp2PXCbTQjIUKpKVkC?=
 =?us-ascii?Q?Cw=3D=3D?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: c55b6db6-194f-498b-421d-08da6b456600
X-MS-Exchange-CrossTenant-AuthSource: CO1PR10MB4531.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Jul 2022 18:18:23.6106
 (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: ffUrlVPjUNcIsndQo8s++iPoyA+FXmwG3XQqFad2WfbxuLiQA745/WF+1KDbfasWgILBACEJrgSm1PFXaU/vDurH5mFLCyTMBFO6Gf4VpSo=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR10MB3986
X-Proofpoint-Virus-Version: vendor=baseguard
 engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1
 definitions=2022-07-21_25,2022-07-21_02,2022-06-22_01
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 suspectscore=0
 mlxlogscore=999 malwarescore=0 adultscore=0 mlxscore=0 spamscore=0
 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1
 engine=8.12.0-2206140000 definitions=main-2207210074
X-Proofpoint-ORIG-GUID: SlYnd8HXhG70Vviw_reGeVOMaUZKuOdu
X-Proofpoint-GUID: SlYnd8HXhG70Vviw_reGeVOMaUZKuOdu
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 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 154ef532d45a..77f5f3591760 100644
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -355,6 +355,11 @@ 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;
@@ -641,6 +646,16 @@ 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, cpu);
 
-- 
2.31.1