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Sat, 17 Feb 2024 08:16:15 +0000 (GMT) Received: from smtpav02.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 42A5A2004E; Sat, 17 Feb 2024 08:16:04 +0000 (GMT) Received: from li-4f5ba44c-27d4-11b2-a85c-a08f5b49eada.ibm.com.com (unknown [9.61.135.227]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Sat, 17 Feb 2024 08:16:03 +0000 (GMT) From: Sourabh Jain To: linuxppc-dev@ozlabs.org Subject: [PATCH v16 5/5] powerpc: add crash memory hotplug support Date: Sat, 17 Feb 2024 13:44:52 +0530 Message-ID: <20240217081452.164571-6-sourabhjain@linux.ibm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240217081452.164571-1-sourabhjain@linux.ibm.com> References: <20240217081452.164571-1-sourabhjain@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: HK2gqbvDsLVl6V7pTLcdWMau9VM3wiMA X-Proofpoint-GUID: 2gWD_lisemouB6CLHvU7LxLYDeSTTAyW 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=2024-02-17_04,2024-02-16_01,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 suspectscore=0 adultscore=0 mlxlogscore=999 clxscore=1015 priorityscore=1501 lowpriorityscore=0 phishscore=0 mlxscore=0 bulkscore=0 spamscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2311290000 definitions=main-2402170064 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: David Hildenbrand , Dave Hansen , Mimi Zohar , Boris Ostrovsky , Valentin Schneider , Baoquan He , x86@kernel.org, "Aneesh Kumar K . V" , Laurent Dufour , Dave Young , Vivek Goyal , Naveen N Rao , Borislav Petkov , Thomas Gleixner , Hari Bathini , Oscar Salvador , Greg Kroah-Hartman , kexec@lists.infradead.org, Mahesh Salgaonkar , Sourabh Jain , Akhil Raj , Andrew Morton Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Extend the arch crash hotplug handler, as introduced by the patch title ("powerpc: add crash CPU hotplug support"), to also support memory add/remove events. Elfcorehdr describes the memory of the crash kernel to capture the kernel; hence, it needs to be updated if memory resources change due to memory add/remove events. Therefore, arch_crash_handle_hotplug_event() is updated to recreate the elfcorehdr and replace it with the previous one on memory add/remove events. The memblock list is used to prepare the elfcorehdr. In the case of memory hot remove, the memblock list is updated after the arch crash hotplug handler is triggered, as depicted in Figure 1. Thus, the hot-removed memory is explicitly removed from the crash memory ranges to ensure that the memory ranges added to elfcorehdr do not include the hot-removed memory. Memory remove | v Offline pages | v Initiate memory notify call <----> crash hotplug handler chain for MEM_OFFLINE event | v Update memblock list Figure 1 There are two system calls, `kexec_file_load` and `kexec_load`, used to load the kdump image. A few changes have been made to ensure that the kernel can safely update the elfcorehdr component of the kdump image for both system calls. For the kexec_file_load syscall, kdump image is prepared in the kernel. To support an increasing number of memory regions, the elfcorehdr is built with extra buffer space to ensure that it can accommodate additional memory ranges in future. For the kexec_load syscall, the elfcorehdr is updated only if the KEXEC_CRASH_HOTPLUG_SUPPORT kexec flag is passed to the kernel by the kexec tool. Passing this flag to the kernel indicates that the elfcorehdr is built to accommodate additional memory ranges and the elfcorehdr segment is not considered for SHA calculation, making it safe to update. The changes related to this feature are kept under the CRASH_HOTPLUG config, and it is enabled by default. Signed-off-by: Sourabh Jain Cc: Akhil Raj Cc: Andrew Morton Cc: Aneesh Kumar K.V Cc: Baoquan He Cc: Borislav Petkov (AMD) Cc: Boris Ostrovsky Cc: Christophe Leroy Cc: Dave Hansen Cc: Dave Young Cc: David Hildenbrand Cc: Greg Kroah-Hartman Cc: Hari Bathini Cc: Laurent Dufour Cc: Mahesh Salgaonkar Cc: Michael Ellerman Cc: Mimi Zohar Cc: Naveen N Rao Cc: Oscar Salvador Cc: Thomas Gleixner Cc: Valentin Schneider Cc: Vivek Goyal Cc: kexec@lists.infradead.org Cc: x86@kernel.org --- arch/powerpc/include/asm/kexec.h | 5 +- arch/powerpc/include/asm/kexec_ranges.h | 1 + arch/powerpc/kexec/core_64.c | 105 +++++++++++++++++++++++- arch/powerpc/kexec/file_load_64.c | 34 +++++++- arch/powerpc/kexec/ranges.c | 85 +++++++++++++++++++ 5 files changed, 226 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/include/asm/kexec.h b/arch/powerpc/include/asm/kexec.h index 67bace4c90cf..a4193d922d99 100644 --- a/arch/powerpc/include/asm/kexec.h +++ b/arch/powerpc/include/asm/kexec.h @@ -116,8 +116,11 @@ int get_crash_memory_ranges(struct crash_mem **mem_ranges); #ifdef CONFIG_CRASH_HOTPLUG void arch_crash_handle_hotplug_event(struct kimage *image, void *arg); #define arch_crash_handle_hotplug_event arch_crash_handle_hotplug_event -#endif /* CONFIG_CRASH_HOTPLUG */ +unsigned int arch_crash_get_elfcorehdr_size(void); +#define crash_get_elfcorehdr_size arch_crash_get_elfcorehdr_size + +#endif /* CONFIG_CRASH_HOTPLUG */ #endif /* CONFIG_PPC64 */ #ifdef CONFIG_KEXEC_FILE diff --git a/arch/powerpc/include/asm/kexec_ranges.h b/arch/powerpc/include/asm/kexec_ranges.h index f83866a19e87..802abf580cf0 100644 --- a/arch/powerpc/include/asm/kexec_ranges.h +++ b/arch/powerpc/include/asm/kexec_ranges.h @@ -7,6 +7,7 @@ void sort_memory_ranges(struct crash_mem *mrngs, bool merge); struct crash_mem *realloc_mem_ranges(struct crash_mem **mem_ranges); int add_mem_range(struct crash_mem **mem_ranges, u64 base, u64 size); +int remove_mem_range(struct crash_mem **mem_ranges, u64 base, u64 size); int add_tce_mem_ranges(struct crash_mem **mem_ranges); int add_initrd_mem_range(struct crash_mem **mem_ranges); #ifdef CONFIG_PPC_64S_HASH_MMU diff --git a/arch/powerpc/kexec/core_64.c b/arch/powerpc/kexec/core_64.c index ff04cdc80f3d..6f188b5ef51e 100644 --- a/arch/powerpc/kexec/core_64.c +++ b/arch/powerpc/kexec/core_64.c @@ -19,8 +19,11 @@ #include #include #include +#include #include +#include +#include #include #include #include @@ -590,6 +593,103 @@ late_initcall(export_htab_values); #undef pr_fmt #define pr_fmt(fmt) "crash hp: " fmt +/* + * Advertise preferred elfcorehdr size to userspace via + * /sys/kernel/crash_elfcorehdr_size sysfs interface. + */ +unsigned int arch_crash_get_elfcorehdr_size(void) +{ + unsigned int sz; + unsigned long elf_phdr_cnt; + + /* Program header for CPU notes and vmcoreinfo */ + elf_phdr_cnt = 2; + if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) + /* In the worst case, a Phdr is needed for every other LMB to be + * represented as an individual crash range. + */ + elf_phdr_cnt += memory_hotplug_max() / (2 * drmem_lmb_size()); + + /* Do not cross the max limit */ + if (elf_phdr_cnt > PN_XNUM) + elf_phdr_cnt = PN_XNUM; + + sz = sizeof(struct elfhdr) + (elf_phdr_cnt * sizeof(Elf64_Phdr)); + return sz; +} + +/** + * update_crash_elfcorehdr() - Recreate the elfcorehdr and replace it with old + * elfcorehdr in the kexec segment array. + * @image: the active struct kimage + * @mn: struct memory_notify data handler + */ +static void update_crash_elfcorehdr(struct kimage *image, struct memory_notify *mn) +{ + int ret; + struct crash_mem *cmem = NULL; + struct kexec_segment *ksegment; + void *ptr, *mem, *elfbuf = NULL; + unsigned long elfsz, memsz, base_addr, size; + + ksegment = &image->segment[image->elfcorehdr_index]; + mem = (void *) ksegment->mem; + memsz = ksegment->memsz; + + ret = get_crash_memory_ranges(&cmem); + if (ret) { + pr_err("Failed to get crash mem range\n"); + return; + } + + /* + * The hot unplugged memory is part of crash memory ranges, + * remove it here. + */ + if (image->hp_action == KEXEC_CRASH_HP_REMOVE_MEMORY) { + base_addr = PFN_PHYS(mn->start_pfn); + size = mn->nr_pages * PAGE_SIZE; + ret = remove_mem_range(&cmem, base_addr, size); + if (ret) { + pr_err("Failed to remove hot-unplugged memory from crash memory ranges\n"); + goto out; + } + } + + ret = crash_prepare_elf64_headers(cmem, false, &elfbuf, &elfsz); + if (ret) { + pr_err("Failed to prepare elf header\n"); + goto out; + } + + /* + * It is unlikely that kernel hit this because elfcorehdr kexec + * segment (memsz) is built with addition space to accommodate growing + * number of crash memory ranges while loading the kdump kernel. It is + * Just to avoid any unforeseen case. + */ + if (elfsz > memsz) { + pr_err("Updated crash elfcorehdr elfsz %lu > memsz %lu", elfsz, memsz); + goto out; + } + + ptr = __va(mem); + if (ptr) { + /* Temporarily invalidate the crash image while it is replaced */ + xchg(&kexec_crash_image, NULL); + + /* Replace the old elfcorehdr with newly prepared elfcorehdr */ + memcpy((void *)ptr, elfbuf, elfsz); + + /* The crash image is now valid once again */ + xchg(&kexec_crash_image, image); + } +out: + kvfree(cmem); + if (elfbuf) + kvfree(elfbuf); +} + /** * get_fdt_index - Loop through the kexec segment array and find * the index of the FDT segment. @@ -661,6 +761,8 @@ static void update_crash_fdt(struct kimage *image) */ void arch_crash_handle_hotplug_event(struct kimage *image, void *arg) { + struct memory_notify *mn; + switch (image->hp_action) { case KEXEC_CRASH_HP_REMOVE_CPU: return; @@ -671,7 +773,8 @@ void arch_crash_handle_hotplug_event(struct kimage *image, void *arg) case KEXEC_CRASH_HP_REMOVE_MEMORY: case KEXEC_CRASH_HP_ADD_MEMORY: - pr_info_once("Crash update is not supported for memory hotplug\n"); + mn = (struct memory_notify *)arg; + update_crash_elfcorehdr(image, mn); return; default: pr_warn_once("Unknown hotplug action\n"); diff --git a/arch/powerpc/kexec/file_load_64.c b/arch/powerpc/kexec/file_load_64.c index d4f4fb19377b..8e5fb774e8b0 100644 --- a/arch/powerpc/kexec/file_load_64.c +++ b/arch/powerpc/kexec/file_load_64.c @@ -21,6 +21,8 @@ #include #include #include +#include + #include #include #include @@ -740,7 +742,35 @@ static int load_elfcorehdr_segment(struct kimage *image, struct kexec_buf *kbuf) kbuf->buffer = headers; kbuf->mem = KEXEC_BUF_MEM_UNKNOWN; - kbuf->bufsz = kbuf->memsz = headers_sz; + kbuf->bufsz = headers_sz; +#if defined(CONFIG_CRASH_HOTPLUG) && defined(CONFIG_MEMORY_HOTPLUG) + /* Adjust the elfcorehdr segment size to accommodate + * future crash memory ranges. + */ + int max_lmb; + unsigned long pnum; + + /* In the worst case, a Phdr is needed for every other LMB to be + * represented as an individual crash range. + */ + max_lmb = memory_hotplug_max() / (2 * drmem_lmb_size()); + + /* Do not cross the Phdr max limit of the elf header. + * Avoid counting Phdr for crash ranges (cmem->nr_ranges) + * which are already part of elfcorehdr. + */ + if (max_lmb > PN_XNUM) + pnum = PN_XNUM - cmem->nr_ranges; + else + pnum = max_lmb - cmem->nr_ranges; + + /* Additional buffer space for elfcorehdr to accommodate + * future memory ranges. + */ + kbuf->memsz = headers_sz + pnum * sizeof(Elf64_Phdr); +#else + kbuf->memsz = headers_sz; +#endif kbuf->top_down = false; ret = kexec_add_buffer(kbuf); @@ -750,7 +780,7 @@ static int load_elfcorehdr_segment(struct kimage *image, struct kexec_buf *kbuf) } image->elf_load_addr = kbuf->mem; - image->elf_headers_sz = headers_sz; + image->elf_headers_sz = kbuf->memsz; image->elf_headers = headers; out: kfree(cmem); diff --git a/arch/powerpc/kexec/ranges.c b/arch/powerpc/kexec/ranges.c index fb3e12f15214..4fd0c5d5607b 100644 --- a/arch/powerpc/kexec/ranges.c +++ b/arch/powerpc/kexec/ranges.c @@ -234,6 +234,91 @@ int add_mem_range(struct crash_mem **mem_ranges, u64 base, u64 size) return __add_mem_range(mem_ranges, base, size); } +/** + * remove_mem_range - Removes the given memory range from the range list. + * @mem_ranges: Range list to remove the memory range to. + * @base: Base address of the range to remove. + * @size: Size of the memory range to remove. + * + * (Re)allocates memory, if needed. + * + * Returns 0 on success, negative errno on error. + */ +int remove_mem_range(struct crash_mem **mem_ranges, u64 base, u64 size) +{ + u64 end; + int ret = 0; + unsigned int i; + u64 mstart, mend; + struct crash_mem *mem_rngs = *mem_ranges; + + if (!size) + return 0; + + /* + * Memory range are stored as start and end address, use + * the same format to do remove operation. + */ + end = base + size - 1; + + for (i = 0; i < mem_rngs->nr_ranges; i++) { + mstart = mem_rngs->ranges[i].start; + mend = mem_rngs->ranges[i].end; + + /* + * Memory range to remove is not part of this range entry + * in the memory range list + */ + if (!(base >= mstart && end <= mend)) + continue; + + /* + * Memory range to remove is equivalent to this entry in the + * memory range list. Remove the range entry from the list. + */ + if (base == mstart && end == mend) { + for (; i < mem_rngs->nr_ranges - 1; i++) { + mem_rngs->ranges[i].start = mem_rngs->ranges[i+1].start; + mem_rngs->ranges[i].end = mem_rngs->ranges[i+1].end; + } + mem_rngs->nr_ranges--; + goto out; + } + /* + * Start address of the memory range to remove and the + * current memory range entry in the list is same. Just + * move the start address of the current memory range + * entry in the list to end + 1. + */ + else if (base == mstart) { + mem_rngs->ranges[i].start = end + 1; + goto out; + } + /* + * End address of the memory range to remove and the + * current memory range entry in the list is same. + * Just move the end address of the current memory + * range entry in the list to base - 1. + */ + else if (end == mend) { + mem_rngs->ranges[i].end = base - 1; + goto out; + } + /* + * Memory range to remove is not at the edge of current + * memory range entry. Split the current memory entry into + * two half. + */ + else { + mem_rngs->ranges[i].end = base - 1; + size = mem_rngs->ranges[i].end - end; + ret = add_mem_range(mem_ranges, end + 1, size); + } + } +out: + return ret; +} + /** * add_tce_mem_ranges - Adds tce-table range to the given memory ranges list. * @mem_ranges: Range list to add the memory range(s) to. -- 2.43.0