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(p200300cbc74fd600c705bc2517b271c9.dip0.t-ipconnect.de. [2003:cb:c74f:d600:c705:bc25:17b2:71c9]) by smtp.gmail.com with ESMTPSA id x18-20020adfdd92000000b0031aeca90e1fsm12117706wrl.70.2023.09.12.00.13.05 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Sep 2023 00:13:05 -0700 (PDT) Message-ID: <3a37361d-1f3b-c283-3fb0-ab3614e3d38c@redhat.com> Date: Tue, 12 Sep 2023 09:13:04 +0200 Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: 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 V2 2/2] proc/kcore: Do not try to access unaccepted memory To: Adrian Hunter , "Kirill A. Shutemov" , Borislav Petkov , Andrew Morton , Ard Biesheuvel Cc: 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: <20230911112114.91323-1-adrian.hunter@intel.com> <20230911112114.91323-3-adrian.hunter@intel.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230911112114.91323-3-adrian.hunter@intel.com> 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 On 11.09.23 13:21, 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 try to access unaccepted memory because it can cause the guest to > fail. > > For /proc/kcore, which is read-only and does not support mmap, this means a > read of unaccepted memory will return zeros. > > Signed-off-by: Adrian Hunter > --- > fs/proc/kcore.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > > Changes in V2: > > Change patch subject and commit message > Do not open code pfn_is_unaccepted_memory() > > > diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c > index 23fc24d16b31..6422e569b080 100644 > --- a/fs/proc/kcore.c > +++ b/fs/proc/kcore.c > @@ -546,7 +546,8 @@ static ssize_t read_kcore_iter(struct kiocb *iocb, struct iov_iter *iter) > * and explicitly excluded physical ranges. > */ > if (!page || PageOffline(page) || > - is_page_hwpoison(page) || !pfn_is_ram(pfn)) { > + is_page_hwpoison(page) || !pfn_is_ram(pfn) || > + pfn_is_unaccepted_memory(pfn)) { > if (iov_iter_zero(tsz, iter) != tsz) { > ret = -EFAULT; > goto out; Reviewed-by: David Hildenbrand -- Cheers, David / dhildenb