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Wed, 15 Jul 2020 09:19:04 +0000 (UTC) Subject: Re: [PATCH RFCv2 3/6] s390x/diag: implement diag260 To: Claudio Imbrenda References: <20200710151239.39370-1-david@redhat.com> <20200710151239.39370-4-david@redhat.com> <20200714121718.45f9f3ed@ibm-vm> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+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 B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMGCwkIBwMCBhUIAgkKCwQW 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/mWutNPt95w9wSsUyATLmtNrwccz63W5Ag0EVcufkQEQAOfX3n0g0fZz 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+w6DABEBAAGJAjwEGAEIACYCGwwWIQQb2cqtc1xMOkYN/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 GmbH Message-ID: Date: Wed, 15 Jul 2020 11:19:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.9.0 MIME-Version: 1.0 In-Reply-To: <20200714121718.45f9f3ed@ibm-vm> Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=207.211.31.81; envelope-from=david@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/07/15 02:01:40 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Thomas Huth , Janosch Frank , "Michael S . Tsirkin" , Heiko Carstens , Cornelia Huck , qemu-devel@nongnu.org, Halil Pasic , Christian Borntraeger , qemu-s390x@nongnu.org, Richard Henderson Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On 14.07.20 12:17, Claudio Imbrenda wrote: > On Fri, 10 Jul 2020 17:12:36 +0200 > David Hildenbrand wrote: > >> Let's implement diag260 - "Access Certain Virtual Machine >> Information", used under z/VM to expose the storage configuration >> (especially, layout of storage extends and thereby holes). For now, >> the returned information is completely redundant to the information >> exposed via SCLP. >> >> We want to reuse diag260 in QEMU to implement memory devices - to >> have a mechanism to indicate to the guest OS that the initial ram >> size and the maximum possible physical address differ. >> >> The Linux kernel supports diag260 (0x10) to query the available memory >> since v4.20. Ancient Linux versions used diag 260 (0xc), but stopped >> doing so a while ago. >> >> Let's unconditionally implement the new diag, without any migration >> checks (e.g., compatibility machine, CPU model). Although a guest OS >> could observe this when migrating between QEMU evrsions, it's somewhat >> unlikely to ever trigger due to the way diag260 is used within a guest >> OS - called only once or twice during boot. >> >> Signed-off-by: David Hildenbrand >> --- >> target/s390x/diag.c | 51 >> ++++++++++++++++++++++++++++++++++++++ target/s390x/internal.h | >> 2 ++ target/s390x/kvm.c | 11 ++++++++ >> target/s390x/misc_helper.c | 6 +++++ >> target/s390x/translate.c | 7 ++++++ >> 5 files changed, 77 insertions(+) >> >> diff --git a/target/s390x/diag.c b/target/s390x/diag.c >> index be70aecd72..5378fcf582 100644 >> --- a/target/s390x/diag.c >> +++ b/target/s390x/diag.c >> @@ -23,6 +23,57 @@ >> #include "hw/s390x/pv.h" >> #include "kvm_s390x.h" >> >> +void handle_diag_260(CPUS390XState *env, uint64_t r1, uint64_t r3, >> uintptr_t ra) +{ >> + MachineState *ms = MACHINE(qdev_get_machine()); >> + const ram_addr_t initial_ram_size = ms->ram_size; >> + const uint64_t subcode = env->regs[r3]; >> + >> + switch (subcode) { >> + case 0xc: >> + /* The first storage extent maps to our initial ram. */ >> + env->regs[r1] = initial_ram_size - 1; >> + /* The highest addressable byte maps to the initial ram size >> for now. */ >> + env->regs[r3] = initial_ram_size - 1; >> + break; >> + case 0x10: { >> + ram_addr_t addr, length; >> + uint64_t tmp; >> + >> + if (r1 & 1) { >> + s390_program_interrupt(env, PGM_SPECIFICATION, ra); >> + return; >> + } >> + >> + addr = env->regs[r1]; >> + length = env->regs[r1 + 1]; >> + if (!QEMU_IS_ALIGNED(addr, 16) || !QEMU_IS_ALIGNED(length, >> 16) || >> + !length) { >> + s390_program_interrupt(env, PGM_SPECIFICATION, ra); >> + return; >> + } >> + if (!address_space_access_valid(&address_space_memory, addr, >> length, >> + true, >> MEMTXATTRS_UNSPECIFIED)) { >> + s390_program_interrupt(env, PGM_ADDRESSING, ra); >> + return; >> + } >> + >> + /* Indicate our initial memory ([0 .. ram_size - 1]) */ >> + tmp = cpu_to_be64(0); >> + cpu_physical_memory_write(addr, &tmp, sizeof(tmp)); >> + tmp = cpu_to_be64(initial_ram_size - 1); >> + cpu_physical_memory_write(addr + sizeof(tmp), &tmp, >> sizeof(tmp)); + >> + /* Exactly one entry was stored, it always fits into the >> area. */ > > maybe I missed something, but I have the impression that your > implementation of DIAG 260 always only returns the first extent? We only indicate boot memory (e.g., -m 2G), never any memory part of the device memory address space, because such memory has different semantics. > > shouldn't it return all the hotplugged areas once hotplugging is > enabled? No, that would be dangerous and wrong. Memory ranges part of memory devices never must be indicated as part of hw/firmware interfaces to indicate valid boot memory. Memory provided via memory devices (virtio-mem, virtio-pmem, ...) has different semantics than ordinary hotplugged memory, and unmodified OSs (esp., older Linux versions) should not silently try to make use of any such memory. It's not just some hotplugged memory a guest OS should detect+use during boot as system ram. Thanks! -- Thanks, David / dhildenb