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Fri, 21 Jul 2023 10:50:07 -0700 (PDT) Date: Fri, 21 Jul 2023 10:50:06 -0700 In-Reply-To: <8ad7a846-64e9-a3f1-4bf1-731a994d62cb@redhat.com> Mime-Version: 1.0 References: <20230718234512.1690985-1-seanjc@google.com> <20230718234512.1690985-13-seanjc@google.com> <8ad7a846-64e9-a3f1-4bf1-731a994d62cb@redhat.com> Message-ID: Subject: Re: [RFC PATCH v11 12/29] KVM: Add KVM_CREATE_GUEST_MEMFD ioctl() for guest-specific backing memory From: Sean Christopherson To: Paolo Bonzini Cc: Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , "Matthew Wilcox (Oracle)" , Andrew Morton , Paul Moore , James Morris , "Serge E. Hallyn" , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, Chao Peng , Fuad Tabba , Jarkko Sakkinen , Yu Zhang , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , Vlastimil Babka , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" Content-Type: text/plain; charset="us-ascii" X-Rspamd-Queue-Id: 9B1322002B X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: hhth447ngoj8zn6qzf6h34f3jx1bx6tz X-HE-Tag: 1689961808-360137 X-HE-Meta: U2FsdGVkX19fTEzaE8fxQrrmnVpBbQMBvwAr3z+ghnWWn9SLoKigqNEdHfYLxvxs9CTVEy3PxNO58yXtFGAMZd+xRX5bqlO40hGccQB/aIHU4VmzGqlCn5yg09xmLZ1/4b0GmIoR78nseI+7OYKKbwMUqUvysbtexsfeBkOg5roOMWo83ad9Ud4niSD3udk0838gimjhBIpnDVJfmPYSeg3mkXl4G22fe8xj7pDXym5+bIrVE9GIrypITCA0IKHJAxRE4vPKMTTqAQcG+5pGcFeUt3q7+yAceRrA2A4yIadXd2udlfx7lgTwO2ZhY06TYgU/FXJfptp4YLoro33i4EVvd5wOZ+BxytxT4Kc4OQ2coUKg67Rp5YHdTPsQbteu8Nh+0InMfuBYqQ42jd3w2TNvlxbo0zDEwSxmfWvce442CEgAFg5pQP5PfRJjzUmASpfoOaWYXFCCi03D7WsBvN9ukQaD+KZkFvBcoyHEHwxcBJwO8IQg3bHuHQQRoKHHutVVcdAZA7wIjRDurolCkgaYR70qztIyK8LIMSH5uN5PVt27bSCRbqIrYN6WWImc22mCWqMKyVeSPW04MzgVmDrGVRmQWHFqFt41GIQ9oST7kRfxXoe3h1ousHG7ZClnk/+1qHPzuJo7M9iC6DskXes31856jKu4NfiBvpHGVemw2sp1FlS1TBt0WFNGGmGNCsinz03ZxIvCEb1Plhx54Xx8Scp2vVdkBmP5oMZKnDZjjEKMFItPcb+bY+GFQEEHqogUeUx8h6gjkeFBRvLLiUazkVg9JbroLHly9J9JwEOLF4osGAkdE+S0iSJP6eYn9avfdg/AMseEjJN/UqaCayeXFoVDwW+P+/gKuBBLp5Makf/Gh2c6LGSenVqqLXMEAvZWSyaqDDHOEN6JCWGNI9UV9LVNJ2j9g+wOG7xu2B18C455ZSedCXU6HP7BuRQE+WVSdE5Q8ui55+YkbLl 9186kCLj 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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: On Fri, Jul 21, 2023, Paolo Bonzini wrote: > On 7/19/23 01:44, Sean Christopherson wrote: > > + inode = alloc_anon_inode(mnt->mnt_sb); > > + if (IS_ERR(inode)) > > + return PTR_ERR(inode); > > + > > + err = security_inode_init_security_anon(inode, &qname, NULL); > > + if (err) > > + goto err_inode; > > + > > I don't understand the need to have a separate filesystem. If it is to > fully setup the inode before it's given a struct file, why not just export > anon_inode_make_secure_inode instead of security_inode_init_security_anon? Ugh, this is why comments are important, I can't remember either. I suspect I implemented a dedicated filesystem to kinda sorta show that we could allow userspace to provide the mount point with e.g. NUMA hints[*]. But my preference would be to not support a userspace provided mount and instead implement fbind() to let userspace control NUMA and whatnot. [*] https://lore.kernel.org/all/ef48935e5e6f947f6f0c6d748232b14ef5d5ad70.1681176340.git.ackerleytng@google.com