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[142.162.113.129]) by smtp.gmail.com with ESMTPSA id n19sm4455570qta.78.2021.11.22.05.31.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 22 Nov 2021 05:31:46 -0800 (PST) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1mp9Q9-00DrvP-FD; Mon, 22 Nov 2021 09:31:45 -0400 Date: Mon, 22 Nov 2021 09:31:45 -0400 From: Jason Gunthorpe To: David Hildenbrand Cc: Chao Peng , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, qemu-devel@nongnu.org, Paolo Bonzini , Jonathan Corbet , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , Hugh Dickins , Jeff Layton , "J . Bruce Fields" , Andrew Morton , Yu Zhang , "Kirill A . Shutemov" , luto@kernel.org, john.ji@intel.com, susie.li@intel.com, jun.nakajima@intel.com, dave.hansen@intel.com, ak@linux.intel.com Subject: Re: [RFC v2 PATCH 01/13] mm/shmem: Introduce F_SEAL_GUEST Message-ID: <20211122133145.GQ876299@ziepe.ca> References: <20211119134739.20218-1-chao.p.peng@linux.intel.com> <20211119134739.20218-2-chao.p.peng@linux.intel.com> <20211119151943.GH876299@ziepe.ca> <20211119160023.GI876299@ziepe.ca> <4efdccac-245f-eb1f-5b7f-c1044ff0103d@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4efdccac-245f-eb1f-5b7f-c1044ff0103d@redhat.com> X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: A6BFB700009B X-Stat-Signature: 1pgory5ybwfgae18b1zqm71wu8gordx6 Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=ziepe.ca header.s=google header.b=CRLeFVla; dmarc=none; spf=pass (imf27.hostedemail.com: domain of jgg@ziepe.ca designates 209.85.222.180 as permitted sender) smtp.mailfrom=jgg@ziepe.ca X-HE-Tag: 1637587906-610201 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 Mon, Nov 22, 2021 at 10:26:12AM +0100, David Hildenbrand wrote: > I do wonder if we want to support sharing such memfds between processes > in all cases ... we most certainly don't want to be able to share > encrypted memory between VMs (I heard that the kernel has to forbid > that). It would make sense in the use case you describe, though. If there is a F_SEAL_XX that blocks every kind of new access, who cares if userspace passes the FD around or not? Jason