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Thu, 13 Apr 2023 10:22:13 -0700 (PDT) Date: Thu, 13 Apr 2023 17:22:12 +0000 In-Reply-To: <20221202061347.1070246-2-chao.p.peng@linux.intel.com> (message from Chao Peng on Fri, 2 Dec 2022 14:13:39 +0800) Mime-Version: 1.0 Message-ID: Subject: Re: [PATCH v10 1/9] mm: Introduce memfd_restricted system call to create restricted user memory From: Ackerley Tng To: Chao Peng Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, linux-doc@vger.kernel.org, qemu-devel@nongnu.org, pbonzini@redhat.com, corbet@lwn.net, seanjc@google.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, arnd@arndb.de, naoya.horiguchi@nec.com, linmiaohe@huawei.com, x86@kernel.org, hpa@zytor.com, hughd@google.com, jlayton@kernel.org, bfields@fieldses.org, akpm@linux-foundation.org, shuah@kernel.org, rppt@kernel.org, steven.price@arm.com, mail@maciej.szmigiero.name, vbabka@suse.cz, vannapurve@google.com, yu.c.zhang@linux.intel.com, chao.p.peng@linux.intel.com, kirill.shutemov@linux.intel.com, luto@kernel.org, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com, david@redhat.com, aarcange@redhat.com, ddutile@redhat.com, dhildenb@redhat.com, qperret@google.com, tabba@google.com, michael.roth@amd.com, mhocko@suse.com, wei.w.wang@intel.com Content-Type: text/plain; charset="UTF-8"; format=flowed; delsp=yes X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: 24A3B1C0015 X-Stat-Signature: uusxghzfhcirhm373chqsrcudu14cdy9 X-HE-Tag: 1681406534-629054 X-HE-Meta: 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 YxCM5SVS 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 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: Chao Peng writes: > From: "Kirill A. Shutemov" > Introduce 'memfd_restricted' system call with the ability to create > memory areas that are restricted from userspace access through ordinary > MMU operations (e.g. read/write/mmap). The memory content is expected to > be used through the new in-kernel interface by a third kernel module. > ... > diff --git a/mm/restrictedmem.c b/mm/restrictedmem.c > new file mode 100644 > index 000000000000..56953c204e5c > --- /dev/null > +++ b/mm/restrictedmem.c > @@ -0,0 +1,318 @@ > +// SPDX-License-Identifier: GPL-2.0 > +#include "linux/sbitmap.h" > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +struct restrictedmem_data { > + struct mutex lock; > + struct file *memfd; Can this be renamed to file, or lower_file (as in stacking filesystems)? It's a little confusing because this pointer doesn't actually refer to an fd. 'memfd' is already used by udmabuf to refer to an actual fd [1], which makes this a little misleading. [1] https://elixir.bootlin.com/linux/v6.2.10/source/tools/testing/selftests/drivers/dma-buf/udmabuf.c#L63 > + struct list_head notifiers; > +}; > + > ...