From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 57693C4345F for ; Tue, 16 Apr 2024 08:13:19 +0000 (UTC) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=i+BL93tf; dkim-atps=neutral Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4VJcHL0MbLz3dVr for ; Tue, 16 Apr 2024 18:13:18 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=i+BL93tf; dkim-atps=neutral Received: from gandalf.ozlabs.org (mail.ozlabs.org [IPv6:2404:9400:2221:ea00::3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4VJcGV3SdVz2yt0 for ; Tue, 16 Apr 2024 18:12:34 +1000 (AEST) Received: from gandalf.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) by gandalf.ozlabs.org (Postfix) with ESMTP id 4VJcGV3DS5z4x1P for ; Tue, 16 Apr 2024 18:12:34 +1000 (AEST) Received: by gandalf.ozlabs.org (Postfix) id 4VJcGV2vY5z4x3k; Tue, 16 Apr 2024 18:12:34 +1000 (AEST) Authentication-Results: gandalf.ozlabs.org; dmarc=pass (p=none dis=none) header.from=linux.ibm.com Authentication-Results: gandalf.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=i+BL93tf; dkim-atps=neutral Authentication-Results: gandalf.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.ibm.com (client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com; envelope-from=sourabhjain@linux.ibm.com; receiver=ozlabs.org) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by gandalf.ozlabs.org (Postfix) with ESMTPS id 4VJcGV0LV4z4x1P for ; Tue, 16 Apr 2024 18:12:33 +1000 (AEST) Received: from pps.filterd (m0353729.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 43G82A3F016493; Tue, 16 Apr 2024 08:12:29 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : content-transfer-encoding : mime-version; s=pp1; bh=6CTqsEb7HzMnG7XdLyQ/zZ3ZzF32qWqPGTt9LmnTKIM=; b=i+BL93tfuw4etYbhTT1pQdwQ2S5aIqdgtHbcs362PcZXdYWhdeYVd9vuP0wvT7np4thL 297elBO1PW/xNtgP2oubK7RVErvSbsfPaUzRjoQ9QeU4jD71c5f+tE83IPk2OD6jaJ0K DwBDw9cBtvchYKhQ3/Yw3ozszd5LE0sqv1WjOLiP4no071r/7hoarmPj9Di/FUL4zfzv esbrTHCSbnLBzY7EtxBxeiG6ILsY9i0qk/w5lWtUx8PS7AqAgUnx0jRtRC+OWhTpszY/ jQ674l9WAIhUC7tabZrEAbMCr4iwh9v/z+OMy1MUUzH8TUJvp/ny2E7Vk2DWHeXmtwyq Bw== Received: from ppma21.wdc07v.mail.ibm.com (5b.69.3da9.ip4.static.sl-reverse.com [169.61.105.91]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3xhnf9r0s3-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 16 Apr 2024 08:12:29 +0000 Received: from pps.filterd (ppma21.wdc07v.mail.ibm.com [127.0.0.1]) by ppma21.wdc07v.mail.ibm.com (8.17.1.19/8.17.1.19) with ESMTP id 43G5jtqq023582; Tue, 16 Apr 2024 08:09:00 GMT Received: from smtprelay01.fra02v.mail.ibm.com ([9.218.2.227]) by ppma21.wdc07v.mail.ibm.com (PPS) with ESMTPS id 3xg5cnvwqx-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 16 Apr 2024 08:09:00 +0000 Received: from smtpav04.fra02v.mail.ibm.com (smtpav04.fra02v.mail.ibm.com [10.20.54.103]) by smtprelay01.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 43G88tMt42533342 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 16 Apr 2024 08:08:57 GMT Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id EF7F82004D; Tue, 16 Apr 2024 08:08:54 +0000 (GMT) Received: from smtpav04.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id F193520040; Tue, 16 Apr 2024 08:08:51 +0000 (GMT) Received: from li-4f5ba44c-27d4-11b2-a85c-a08f5b49eada.ibm.com.com (unknown [9.43.85.254]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 16 Apr 2024 08:08:51 +0000 (GMT) From: Sourabh Jain To: linuxppc-dev@ozlabs.org Subject: [PATCH v9 0/3] powerpc: make fadump resilient with memory add/remove events Date: Tue, 16 Apr 2024 13:38:45 +0530 Message-ID: <20240416080848.347602-1-sourabhjain@linux.ibm.com> X-Mailer: git-send-email 2.43.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: smAmjlcpRsltvyfpyb3uJYqrRsdfonY8 X-Proofpoint-GUID: smAmjlcpRsltvyfpyb3uJYqrRsdfonY8 Content-Transfer-Encoding: 8bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.1011,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2024-04-16_06,2024-04-15_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 suspectscore=0 adultscore=0 impostorscore=0 mlxscore=0 mlxlogscore=999 bulkscore=0 priorityscore=1501 clxscore=1015 lowpriorityscore=0 spamscore=0 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2404010000 definitions=main-2404160049 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mahesh Salgaonkar , Sourabh Jain , Naveen N Rao , "Aneesh Kumar K.V" , Aditya Gupta , Hari Bathini Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Problem: ======== Due to changes in memory resources caused by either memory hotplug or online/offline events, the elfcorehdr, which describes the cpus and memory of the crashed kernel to the kernel that collects the dump (known as second/fadump kernel), becomes outdated. Consequently, attempting dump collection with an outdated elfcorehdr can lead to failed or inaccurate dump collection. Memory hotplug or online/offline events is referred as memory add/remove events in reset of the patch series. Existing solution: ================== Monitor memory add/remove events in userspace using udev rules, and re-register fadump whenever there are changes in memory resources. This leads to the creation of a new elfcorehdr with updated system memory information. Challenges with existing solution: ================================== 1. Performing bulk memory add/remove with udev-based fadump re-registration can lead to race conditions and, more importantly, it creates a large wide window during which fadump is inactive until all memory add/remove events are settled. 2. Re-registering fadump for every memory add/remove event is inefficient. 3. Memory for elfcorehdr is allocated based on the memblock regions available during first kernel early boot and it remains fixed thereafter. However, if the elfcorehdr is later recreated with additional memblock regions, its size will increase, potentially leading to memory corruption. Proposed solution: ================== Address the aforementioned challenges by shifting the creation of elfcorehdr from the first kernel (also referred as the crashed kernel), where it was created and frequently recreated for every memory add/remove event, to the fadump kernel. As a result, the elfcorehdr only needs to be created once, thus eliminating the necessity to re-register fadump during memory add/remove events. To know more about elfcorehdr creation in the fadump kernel, refer to the first patch in this series. The second patch includes a new sysfs interface that tells userspace that fadump re-registration isn't needed for memory add/remove events. note that userspace changes do not need to be in sync with kernel changes; they can roll out independently. Since there are significant changes in the fadump implementation, the third patch updates the fadump documentation to reflect the changes made in this patch series. Kernel tree rebased on 6.9.0-rc3 with patch series applied: =========================================================== https://github.com/sourabhjains/linux/tree/fadump-mem-hotplug-v9 Userspace changes: ================== To realize this feature, one must update the kdump udev rules to prevent fadump re-registration during memory add/remove events. On rhel apply the following changes to file /usr/lib/udev/rules.d/98-kexec.rules -RUN+="/bin/sh -c '/usr/bin/systemctl is-active kdump.service || exit 0; /usr/bin/systemd-run --quiet --no-block /usr/lib/udev/kdump-udev-throttler'" +# don't re-register fadump if the value of the node +# /sys/kernel/fadump/hotplug_ready is 1. + +RUN+="/bin/sh -c '/usr/bin/systemctl is-active kdump.service || exit 0; ! test -f /sys/kernel/fadump_enabled || cat /sys/kernel/fadump_enabled | grep 0 || ! test -f /sys/kernel/fadump/hotplug_ready || cat /sys/kernel/fadump/hotplug_ready | grep 0 || exit 0; /usr/bin/systemd-run --quiet --no-block /usr/lib/udev/kdump-udev-throttler'" Changelog: ========== v9: 16 Apr 2024 - Set the physical address of elfcorehdr to elfcorehdr_addr. 1/3 - Set elfcorehdr_addr to ELFCORE_ADDR_ERR before freeing the elfcorehdr. 1/3 - Mark the populate_elf_pt_load function as __init. 1/3 - Rename a function from process_fadump to fadump_process. 1/3 - Make minor changes to the commit message and a couple of comments in 1/3. - Update date of introduction of /sys/kernel/fadump/hotplug_ready sysfs. 2/3 - Rebase it to 6.9-rc3. v8: 16 Feb 2024 https://lore.kernel.org/all/20240217072004.148293-1-sourabhjain@linux.ibm.com/ - Move `elfcorehdr_addr` and `elfcorehdr_size` struct attributes from `struct fadump_crash_info_header` to `struct fw_dump`. - Make minor changes in commit message 1/3. - Rebase it to 6.8-rc4. v7: 11 Jan 2024 https://lore.kernel.org/all/20240111140943.297501-1-sourabhjain@linux.ibm.com/ - Rebase it to 6.7 v6: 8 Dec 2023 https://lore.kernel.org/all/20231208115159.82236-1-sourabhjain@linux.ibm.com/ - Add size fields for `pt_regs` and `cpumask` in the fadump header structure - Don't process the dump if the size of `pt_regs` and `cpu_mask` is not same in the crashed and fadump kernel - Include an additional check for endianness mismatch when the magic number doesn't match, to print the relevant error message - Don't process the dump if the fadump header contains an old magic number - Rebased it to 6.7.0-rc4 v5: 29 Oct 2023 https://lore.kernel.org/all/20231029124548.12198-1-sourabhjain@linux.ibm.com/ - Fix a comment on the first patch v4: 21 Oct 2023 https://lore.kernel.org/all/20231021181733.204311-1-sourabhjain@linux.ibm.com/ - Fix a build warning about type casting v3: 9 Oct 2023 https://lore.kernel.org/all/20231009041953.36139-1-sourabhjain@linux.ibm.com/ - Assign physical address of elfcorehdr to fdh->elfcorehdr_addr - Rename a variable, boot_mem_dest_addr -> boot_mem_dest_offset v2: 25 Sep 2023 https://lore.kernel.org/all/20230925051214.678957-1-sourabhjain@linux.ibm.com/ - Fixed a few indentation issues reported by the checkpatch script. - Rebased it to 6.6.0-rc3 v1: 17 Sep 2023 https://lore.kernel.org/all/20230917080225.561627-1-sourabhjain@linux.ibm.com/ Cc: Aditya Gupta Cc: "Aneesh Kumar K.V" Cc: Hari Bathini Cc: Mahesh Salgaonkar Cc: Michael Ellerman Cc: Naveen N Rao Sourabh Jain (3): powerpc: make fadump resilient with memory add/remove events powerpc/fadump: add hotplug_ready sysfs interface Documentation/powerpc: update fadump implementation details Documentation/ABI/testing/sysfs-kernel-fadump | 11 + .../arch/powerpc/firmware-assisted-dump.rst | 91 ++--- arch/powerpc/include/asm/fadump-internal.h | 31 +- arch/powerpc/kernel/fadump.c | 375 ++++++++++-------- arch/powerpc/platforms/powernv/opal-fadump.c | 22 +- arch/powerpc/platforms/pseries/rtas-fadump.c | 34 +- 6 files changed, 309 insertions(+), 255 deletions(-) -- 2.43.0