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(p200300cbc7435500a9bd94ab74e9782f.dip0.t-ipconnect.de. [2003:cb:c743:5500:a9bd:94ab:74e9:782f]) by smtp.gmail.com with ESMTPSA id g12-20020a7bc4cc000000b003fee849df23sm9372755wmk.22.2023.09.11.01.42.51 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 11 Sep 2023 01:42:52 -0700 (PDT) Message-ID: <49ab74c8-553b-b3d0-6a72-2d259a2b5bdf@redhat.com> Date: Mon, 11 Sep 2023 10:42:51 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH 1/3] proc/vmcore: Do not map unaccepted memory To: "Kirill A. Shutemov" Cc: Adrian Hunter , Borislav Petkov , Andrew Morton , Dave Hansen , Vlastimil Babka , Mike Rapoport , Lorenzo Stoakes , Tom Lendacky , Baoquan He , Vivek Goyal , Dave Young , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, linux-efi@vger.kernel.org, kexec@lists.infradead.org References: <20230906073902.4229-1-adrian.hunter@intel.com> <20230906073902.4229-2-adrian.hunter@intel.com> <20230911084148.l6han7jxob42rdvm@box.shutemov.name> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230911084148.l6han7jxob42rdvm@box.shutemov.name> 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-Rspamd-Queue-Id: A78B540019 X-Rspam-User: X-Stat-Signature: uxqat6oh9ktguei1nnkko8k9znfh5nja X-Rspamd-Server: rspam01 X-HE-Tag: 1694421778-306876 X-HE-Meta: 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 scNyh5Qb VPTGhge011jN+rDqtlW9KHow6/Oq/IERbvqQjoJs6JF/EJ6lBYn4VJaCTnZ8iFtnWlOhMNE06P5m+MlfSIGztHRkroLUaSJFA5YXs7WpH23zbm8dA9lVjbystOxjHR1mtuL+HVTEK29EImFUsywGG87ThsBlua9CregOqeUjOZgiQ2Zkz7m1Bb8VaFTCKfMMJM56ecEFSQrL/poFnR7kRS5IJZ6jyup1kOnKg95a72REy8u2tdQx1oCq0jv5jj4vFOhKxUrzs3/0ElwMS3g/qE9f+eMAyu0npabRMNA5CBgdd0hXzoQnSCfvTSadiMuag7d+N9sJIhUZ12laRBjdj6RSndICtJb1Veb23+TGGtKo1XyVo8fYRQC83XrfI/7JFUNp7 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: On 11.09.23 10:41, Kirill A. Shutemov wrote: > On Mon, Sep 11, 2023 at 10:03:36AM +0200, David Hildenbrand wrote: >> On 06.09.23 09:39, Adrian Hunter wrote: >>> Support for unaccepted memory was added recently, refer commit >>> dcdfdd40fa82 ("mm: Add support for unaccepted memory"), whereby >>> a virtual machine may need to accept memory before it can be used. >>> >>> Do not map unaccepted memory because it can cause the guest to fail. >>> >>> For /proc/vmcore, which is read-only, this means a read or mmap of >>> unaccepted memory will return zeros. >> >> Does a second (kdump) kernel that exposes /proc/vmcore reliably get access >> to the information whether memory of the first kernel is unaccepted (IOW, >> not its memory, but the memory of the first kernel it is supposed to expose >> via /proc/vmcore)? > > There are few patches in my queue to few related issue, but generally, > yes, the information is available to the target kernel via EFI > configuration table. I assume that table provided by the first kernel, and not read directly from HW, correct? -- Cheers, David / dhildenb