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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 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-Host-Lookup-Failed: Reverse DNS lookup failed for 2607:f8b0:4864:20::72f (failed) Received-SPF: pass client-ip=2607:f8b0:4864:20::72f; envelope-from=jgg@ziepe.ca; helo=mail-qk1-x72f.google.com X-Spam_score_int: -12 X-Spam_score: -1.3 X-Spam_bar: - X-Spam_report: (-1.3 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, PDS_HP_HELO_NORDNS=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_NONE=0.793, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Wanpeng Li , jun.nakajima@intel.com, kvm@vger.kernel.org, qemu-devel@nongnu.org, "J . Bruce Fields" , linux-mm@kvack.org, "H . Peter Anvin" , Chao Peng , ak@linux.intel.com, Jonathan Corbet , Joerg Roedel , x86@kernel.org, Hugh Dickins , Ingo Molnar , Borislav Petkov , luto@kernel.org, Thomas Gleixner , Vitaly Kuznetsov , Jim Mattson , dave.hansen@intel.com, Sean Christopherson , susie.li@intel.com, Jeff Layton , linux-kernel@vger.kernel.org, john.ji@intel.com, Yu Zhang , linux-fsdevel@vger.kernel.org, Paolo Bonzini , Andrew Morton , "Kirill A . Shutemov" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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