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(p200300cbc705760062cc24c19dbea2f5.dip0.t-ipconnect.de. [2003:cb:c705:7600:62cc:24c1:9dbe:a2f5]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-43158c3dedfsm18012235e9.26.2024.10.17.01.19.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Oct 2024 01:19:39 -0700 (PDT) Message-ID: <04d5169f-3289-4aac-abca-90b20ad4e9c9@redhat.com> Date: Thu, 17 Oct 2024 10:19:36 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 4/7] s390/physmem_info: query diag500(STORAGE LIMIT) to support QEMU/KVM memory devices To: Alexander Gordeev 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, Heiko Carstens , Vasily Gorbik , 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> <20241014144622.876731-5-david@redhat.com> From: David Hildenbrand 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: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: 8yofja5rqdkw67iztgbikbnr3udxbgq9 X-Rspamd-Queue-Id: 8F379C0012 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1729153173-578762 X-HE-Meta: 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 dywNSpwS DyDRPQtDJ8nFRqy88vTd0llZNbVu3E7nSP3oub4cMkLNql+XudOytUQUQr5gI3Cu5uFXma2O+dgvKbRO7gd3LFvsqcBZARV1vk9vRJ78TFmjaOds2bEGi7gJR/QlrpRxMsPmZ9onyP/t6crrjQ+clLkULm3bD8piyTTaOxUXMFj/mR9PZh4OW3d1o3gau8fnleJPbkGn/xG7I0kaUC24NUk/GVGhUGrHp655Fqf2/nvjNpZ27wGDqyCHDXTnTlPL0NPThIXJ7d8E0AgdtDFV0MNKvd4DBVuXEJq/ErwNdFXigGO2wWJsX8RrnFyyQ+FXTwZfOZGllohsBkgGZ4m1arz+RwrHSGQuSPJ5/EO8CwhNzlsm1ReCEysYh2/pvyRY123qQX/c9dWVFSnkxf1ppxhLN3QO1uzk+XdwqL8yq+x1up8HcFk0/mhsGSJ4b5Ihi1/rw X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 17.10.24 09:36, Alexander Gordeev wrote: > On Mon, Oct 14, 2024 at 04:46:16PM +0200, David Hildenbrand wrote: > > Hi David! Hi Alexander! > >> @@ -157,7 +189,9 @@ unsigned long detect_max_physmem_end(void) >> { >> unsigned long max_physmem_end = 0; >> >> - if (!sclp_early_get_memsize(&max_physmem_end)) { >> + if (!diag500_storage_limit(&max_physmem_end)) { >> + physmem_info.info_source = MEM_DETECT_DIAG500_STOR_LIMIT; >> + } else if (!sclp_early_get_memsize(&max_physmem_end)) { >> physmem_info.info_source = MEM_DETECT_SCLP_READ_INFO; >> } else { >> max_physmem_end = search_mem_end(); >> @@ -170,11 +204,17 @@ void detect_physmem_online_ranges(unsigned long max_physmem_end) >> { >> if (!sclp_early_read_storage_info()) { >> physmem_info.info_source = MEM_DETECT_SCLP_STOR_INFO; >> + return; >> } else if (!diag260()) { >> physmem_info.info_source = MEM_DETECT_DIAG260; >> - } else if (max_physmem_end) { >> - add_physmem_online_range(0, max_physmem_end); >> + return; >> + } else if (physmem_info.info_source == MEM_DETECT_DIAG500_STOR_LIMIT) { >> + max_physmem_end = 0; >> + if (!sclp_early_get_memsize(&max_physmem_end)) >> + physmem_info.info_source = MEM_DETECT_SCLP_READ_INFO; > > Why search_mem_end() is not tried in case sclp_early_get_memsize() failed? Patch #3 documents that: + The storage limit does not indicate currently usable storage, it may + include holes, standby storage and areas reserved for other means, such + as memory hotplug or virtio-mem devices. Other interfaces for detecting + actually usable storage, such as SCLP, must be used in conjunction with + this subfunction. If SCLP would fail, something would be seriously wrong and we should just crash instead of trying to fallback to the legacy way of scanning. > >> } >> + if (max_physmem_end) >> + add_physmem_online_range(0, max_physmem_end); >> } >> >> void physmem_set_usable_limit(unsigned long limit) >> diff --git a/arch/s390/include/asm/physmem_info.h b/arch/s390/include/asm/physmem_info.h >> index f45cfc8bc233..51b68a43e195 100644 >> --- a/arch/s390/include/asm/physmem_info.h >> +++ b/arch/s390/include/asm/physmem_info.h >> @@ -9,6 +9,7 @@ enum physmem_info_source { >> MEM_DETECT_NONE = 0, >> MEM_DETECT_SCLP_STOR_INFO, >> MEM_DETECT_DIAG260, >> + MEM_DETECT_DIAG500_STOR_LIMIT, >> MEM_DETECT_SCLP_READ_INFO, >> MEM_DETECT_BIN_SEARCH >> }; >> @@ -107,6 +108,8 @@ static inline const char *get_physmem_info_source(void) >> return "sclp storage info"; >> case MEM_DETECT_DIAG260: >> return "diag260"; >> + case MEM_DETECT_DIAG500_STOR_LIMIT: >> + return "diag500 storage limit"; > > AFAIU you want to always override MEM_DETECT_DIAG500_STOR_LIMIT method > with an online memory detection method. In that case this code is dead. Not in the above case, pathological case above where something went wrong during sclp_early_get_memsize(). In that scenario, die_oom() would indicate that there are no memory ranges but that "diag500 storage limit" worked. Does that make sense? Thanks for the review! -- Cheers, David / dhildenb