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(p200300cbc7309700d653fb1975e5ab5c.dip0.t-ipconnect.de. [2003:cb:c730:9700:d653:fb19:75e5:ab5c]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4313f569eacsm11175035e9.20.2024.10.15.01.53.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 15 Oct 2024 01:53:39 -0700 (PDT) Message-ID: <9be496ff-9d94-4680-b095-863ec12e3261@redhat.com> Date: Tue, 15 Oct 2024 10:53:37 +0200 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/7] s390/kdump: implement is_kdump_kernel() From: David Hildenbrand To: Heiko Carstens Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-s390@vger.kernel.org, virtualization@lists.linux.dev, linux-doc@vger.kernel.org, kvm@vger.kernel.org, Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Thomas Huth , Cornelia Huck , Janosch Frank , Claudio Imbrenda , "Michael S. Tsirkin" , Jason Wang , Xuan Zhuo , =?UTF-8?Q?Eugenio_P=C3=A9rez?= , Andrew Morton , Jonathan Corbet , Mario Casquero References: <20241014144622.876731-1-david@redhat.com> <20241014144622.876731-2-david@redhat.com> <20241014182054.10447-D-hca@linux.ibm.com> <20241015083040.7641-C-hca@linux.ibm.com> <0c7e876f-5648-4a82-b809-ca48f778b4a6@redhat.com> Content-Language: en-US Autocrypt: addr=david@redhat.com; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzSREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT7CwZgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW AgMBAh4BAheAAhkBFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl8Ox4kFCRKpKXgACgkQTd4Q 9wD/g1oHcA//a6Tj7SBNjFNM1iNhWUo1lxAja0lpSodSnB2g4FCZ4R61SBR4l/psBL73xktp rDHrx4aSpwkRP6Epu6mLvhlfjmkRG4OynJ5HG1gfv7RJJfnUdUM1z5kdS8JBrOhMJS2c/gPf wv1TGRq2XdMPnfY2o0CxRqpcLkx4vBODvJGl2mQyJF/gPepdDfcT8/PY9BJ7FL6Hrq1gnAo4 3Iv9qV0JiT2wmZciNyYQhmA1V6dyTRiQ4YAc31zOo2IM+xisPzeSHgw3ONY/XhYvfZ9r7W1l pNQdc2G+o4Di9NPFHQQhDw3YTRR1opJaTlRDzxYxzU6ZnUUBghxt9cwUWTpfCktkMZiPSDGd KgQBjnweV2jw9UOTxjb4LXqDjmSNkjDdQUOU69jGMUXgihvo4zhYcMX8F5gWdRtMR7DzW/YE BgVcyxNkMIXoY1aYj6npHYiNQesQlqjU6azjbH70/SXKM5tNRplgW8TNprMDuntdvV9wNkFs 9TyM02V5aWxFfI42+aivc4KEw69SE9KXwC7FSf5wXzuTot97N9Phj/Z3+jx443jo2NR34XgF 89cct7wJMjOF7bBefo0fPPZQuIma0Zym71cP61OP/i11ahNye6HGKfxGCOcs5wW9kRQEk8P9 M/k2wt3mt/fCQnuP/mWutNPt95w9wSsUyATLmtNrwccz63XOwU0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAHCwXwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/MpN3hD3 AP+DWgUCXw7HsgUJEqkpoQAKCRBN3hD3AP+DWrrpD/4qS3dyVRxDcDHIlmguXjC1Q5tZTwNB boaBTPHSy/Nksu0eY7x6HfQJ3xajVH32Ms6t1trDQmPx2iP5+7iDsb7OKAb5eOS8h+BEBDeq 3ecsQDv0fFJOA9ag5O3LLNk+3x3q7e0uo06XMaY7UHS341ozXUUI7wC7iKfoUTv03iO9El5f XpNMx/YrIMduZ2+nd9Di7o5+KIwlb2mAB9sTNHdMrXesX8eBL6T9b+MZJk+mZuPxKNVfEQMQ a5SxUEADIPQTPNvBewdeI80yeOCrN+Zzwy/Mrx9EPeu59Y5vSJOx/z6OUImD/GhX7Xvkt3kq Er5KTrJz3++B6SH9pum9PuoE/k+nntJkNMmQpR4MCBaV/J9gIOPGodDKnjdng+mXliF3Ptu6 3oxc2RCyGzTlxyMwuc2U5Q7KtUNTdDe8T0uE+9b8BLMVQDDfJjqY0VVqSUwImzTDLX9S4g/8 kC4HRcclk8hpyhY2jKGluZO0awwTIMgVEzmTyBphDg/Gx7dZU1Xf8HFuE+UZ5UDHDTnwgv7E th6RC9+WrhDNspZ9fJjKWRbveQgUFCpe1sa77LAw+XFrKmBHXp9ZVIe90RMe2tRL06BGiRZr jPrnvUsUUsjRoRNJjKKA/REq+sAnhkNPPZ/NNMjaZ5b8Tovi8C0tmxiCHaQYqj7G2rgnT0kt WNyWQQ== Organization: Red Hat In-Reply-To: <0c7e876f-5648-4a82-b809-ca48f778b4a6@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 15.10.24 10:41, David Hildenbrand wrote: > On 15.10.24 10:30, Heiko Carstens wrote: >> On Mon, Oct 14, 2024 at 09:26:03PM +0200, David Hildenbrand wrote: >>> On 14.10.24 20:20, Heiko Carstens wrote: >>>> Looks like this could work. But the comment in smp.c above >>>> dump_available() needs to be updated. >>> >>> A right, I remember that there was some outdated documentation. >>> >>>> >>>> Are you willing to do that, or should I provide an addon patch? >>>> >>> >>> I can squash the following: >>> >>> diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c >>> index 4df56fdb2488..a4f538876462 100644 >>> --- a/arch/s390/kernel/smp.c >>> +++ b/arch/s390/kernel/smp.c >>> @@ -587,16 +587,16 @@ int smp_store_status(int cpu) >>> * with sigp stop-and-store-status. The firmware or the boot-loader >>> * stored the registers of the boot CPU in the absolute lowcore in the >>> * memory of the old system. >>> - * 3) kdump and the old kernel did not store the CPU state, >>> - * or stand-alone kdump for DASD >>> - * condition: OLDMEM_BASE != NULL && !is_kdump_kernel() >>> + * 3) kdump or stand-alone kdump for DASD >>> + * condition: OLDMEM_BASE != NULL && !is_ipl_type_dump() == false >>> * The state for all CPUs except the boot CPU needs to be collected >>> * with sigp stop-and-store-status. The kexec code or the boot-loader >>> * stored the registers of the boot CPU in the memory of the old system. >>> - * 4) kdump and the old kernel stored the CPU state >>> - * condition: OLDMEM_BASE != NULL && is_kdump_kernel() >>> - * This case does not exist for s390 anymore, setup_arch explicitly >>> - * deactivates the elfcorehdr= kernel parameter >>> + * >>> + * Note that the old Kdump mode where the old kernel stored the CPU state >> >> To be consistent with the rest of the comment, please write kdump in >> all lower case characters, please. > > It obviously was too late in the evening for me :) Thanks! > >> >>> + * does no longer exist: setup_arch explicitly deactivates the elfcorehdr= >>> + * kernel parameter. The is_kudmp_kernel() implementation on s390 is independent >> >> Typo: kudmp. >> >>> Does that sound reasonable? I'm not so sure about the "2) stand-alone kdump for >>> SCSI/NVMe (zfcp/nvme dump with swapped memory)": is that really "kdump" ? >> >> Yes, it is some sort of kdump, even though a bit odd. > > My concern is that we'll now have > > bool is_kdump_kernel(void) > { > return oldmem_data.start && !is_ipl_type_dump(); > } > > Which matches 3), but if 2) is also called "kdump", then should it > actually be > > bool is_kdump_kernel(void) > { > return oldmem_data.start; > } > > ? > > When I wrote that code I was rather convinced that the variant in this > patch is the right thing to do. > I think we can do some follow up cleanups, assuming is_kdump_kernel() here is correct: diff --git a/arch/s390/kernel/crash_dump.c b/arch/s390/kernel/crash_dump.c index cca1827d3d2e..fbc5de66d03b 100644 --- a/arch/s390/kernel/crash_dump.c +++ b/arch/s390/kernel/crash_dump.c @@ -609,7 +609,7 @@ int elfcorehdr_alloc(unsigned long long *addr, unsigned long long *size) u64 hdr_off; /* If we are not in kdump or zfcp/nvme dump mode return */ - if (!oldmem_data.start && !is_ipl_type_dump()) + if (!dump_available()) return 0; /* If we cannot get HSA size for zfcp/nvme dump return error */ if (is_ipl_type_dump() && !sclp.hsa_size) diff --git a/arch/s390/kernel/os_info.c b/arch/s390/kernel/os_info.c index b695f980bbde..09578f400ef7 100644 --- a/arch/s390/kernel/os_info.c +++ b/arch/s390/kernel/os_info.c @@ -148,7 +148,7 @@ static void os_info_old_init(void) if (os_info_init) return; - if (!oldmem_data.start && !is_ipl_type_dump()) + if (!dump_available()) goto fail; if (copy_oldmem_kernel(&addr, __LC_OS_INFO, sizeof(addr))) goto fail; diff --git a/drivers/s390/char/zcore.c b/drivers/s390/char/zcore.c index 33cebb91b933..6a194b4f6ba5 100644 --- a/drivers/s390/char/zcore.c +++ b/drivers/s390/char/zcore.c @@ -300,9 +300,7 @@ static int __init zcore_init(void) unsigned char arch; int rc; - if (!is_ipl_type_dump()) - return -ENODATA; - if (oldmem_data.start) + if (is_kdump_kernel()) return -ENODATA; zcore_dbf = debug_register("zcore", 4, 1, 4 * sizeof(long)); -- Cheers, David / dhildenb