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(p200300cbc708180042bd3cacd22a3c62.dip0.t-ipconnect.de. [2003:cb:c708:1800:42bd:3cac:d22a:3c62]) by smtp.gmail.com with ESMTPSA id e18-20020adfdbd2000000b001e4bbbe5b92sm17551203wrj.76.2022.03.15.09.58.42 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 15 Mar 2022 09:58:44 -0700 (PDT) Message-ID: <8b13b6c0-78d4-48e3-06f0-ec0680d013a9@redhat.com> Date: Tue, 15 Mar 2022 17:58:42 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.2 Subject: Re: [PATCH v1 5/7] s390/pgtable: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE Content-Language: en-US From: David Hildenbrand To: Gerald Schaefer Cc: linux-kernel@vger.kernel.org, Andrew Morton , Hugh Dickins , Linus Torvalds , David Rientjes , Shakeel Butt , John Hubbard , Jason Gunthorpe , Mike Kravetz , Mike Rapoport , Yang Shi , "Kirill A . Shutemov" , Matthew Wilcox , Vlastimil Babka , Jann Horn , Michal Hocko , Nadav Amit , Rik van Riel , Roman Gushchin , Andrea Arcangeli , Peter Xu , Donald Dutile , Christoph Hellwig , Oleg Nesterov , Jan Kara , Liang Zhang , Pedro Gomes , Oded Gabbay , Catalin Marinas , Will Deacon , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , linux-mm@kvack.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org References: <20220315141837.137118-1-david@redhat.com> <20220315141837.137118-6-david@redhat.com> <20220315172102.771bd2cf@thinkpad> Organization: Red Hat In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >> This would mean that it is not OK to have bit 52 not zero for swap PTEs. >> But if I read the POP correctly, all bits except for the DAT-protection >> would be ignored for invalid PTEs, so maybe this comment needs some update >> (for both bits 52 and also 55). >> >> Heiko might also have some more insight. > > Indeed, I wonder why we should get a specification exception when the > PTE is invalid. I'll dig a bit into the PoP. SA22-7832-12 6-46 ("Translation-Specification Exception") is clearer "The page-table entry used for the translation is valid, and bit position 52 does not contain zero." "The page-table entry used for the translation is valid, EDAT-1 does not apply, the instruction-exe- cution-protection facility is not installed, and bit position 55 does not contain zero. It is model dependent whether this condition is recognized." -- Thanks, David / dhildenb