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AJvYcCXuAwYAUEITvuPEYOEN3Clk+1NYzfW3WMMdnSISz1ykFJM1RPrhfpmiT0izrjVEY9OyfFX2il0oJw==@kvack.org X-Gm-Message-State: AOJu0Yw3AaOunGUQvf5bh0bvsR9jlKa8dxKyOUlmXyHo/4t9m33+hprL ca3EmxHem+mv5eLbqJgr5GcylM94sTLtXAx465iIvO/f9uwG+zUcuWtjCsabyPeP3ACX8ehH5ZY L/HQRE6EG3xYb6lOIxKC8hw== X-Google-Smtp-Source: AGHT+IGEOFVmeMKiNYyGdVgVnjUwRuQMOBh3p67Kck++ZyIayxkYnmKh+TTYDv35m8GZuGIZaSBy6hjI9GDfCfcztg== X-Received: from pjbtb11.prod.google.com ([2002:a17:90b:53cb:b0:301:1ea9:63b0]) (user=ackerleytng job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90a:d2ce:b0:2ee:f440:53ed with SMTP id 98e67ed59e1d1-3072ba1f6e0mr4252531a91.31.1744293196650; Thu, 10 Apr 2025 06:53:16 -0700 (PDT) Date: Thu, 10 Apr 2025 06:53:15 -0700 In-Reply-To: Mime-Version: 1.0 References: <20250408112402.181574-1-shivankg@amd.com> <20250408112402.181574-6-shivankg@amd.com> Message-ID: Subject: Re: [PATCH RFC v7 5/8] KVM: guest_memfd: Make guest mem use guest mem inodes instead of anonymous inodes From: Ackerley Tng To: Christoph Hellwig , Shivank Garg Cc: seanjc@google.com, david@redhat.com, vbabka@suse.cz, willy@infradead.org, akpm@linux-foundation.org, shuah@kernel.org, pbonzini@redhat.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, pvorel@suse.cz, bfoster@redhat.com, tabba@google.com, vannapurve@google.com, chao.gao@intel.com, bharata@amd.com, nikunj@amd.com, michael.day@amd.com, yan.y.zhao@intel.com, Neeraj.Upadhyay@amd.com, thomas.lendacky@amd.com, michael.roth@amd.com, aik@amd.com, jgg@nvidia.com, kalyazin@amazon.com, peterx@redhat.com, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-coco@lists.linux.dev Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: CFAAE4000C X-Stat-Signature: qd7cosijwxgzusyguozxgbem1kterpj5 X-Rspam-User: X-Rspamd-Server: rspam12 X-HE-Tag: 1744293197-62204 X-HE-Meta: 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 pfwMLyXa TbGuxCpph5oNh69rPxtdR6UaRZLZ0Yza2jsI4Myrqg1NCmTCxxtFqEmQSBxnmYlu72+mdQvKOzBuWBcym/i+8fpYIEKsKTjzO1T6/qWgA5Fkg4FhzN2OKEJ+mdZZOb3zvtpO/Wn9q2LEttD6nZjt+HmKshEFFDm37ILBNkASgidwGT99ttGI3S58EVXMq24rwpL8UZHgEkGsryWL50WjSEdcEZiEQYqdeIPmmVKJYIuKp519vgisSwuJwVjI7INzUHx60Yytp4MA1M1tpbGvGkdBYlWH3U0+WwG5ECeS2s5Vo5eaMy3kcgJwYB2q25CyeB0uRYSOqbsOOlN8E81JGxMGvUiVWD7PUQu7qdTLK9P9e7YTb7O/a9ZoBtkMNNq5659dhg8gMkFRRyKheW/AowVkOUlgCbfVv6KXE9M/XE0j0oFGGUPbWLWk8J1cQOxMYZ0Foj5GH4n6r185NuDb33nYnPxpuIDj++1m8gd2v3HHyxCzar0eoo2Lxzbt5QK0mEUkIH4VgsyWaNwgzX+jFwXIdl15EAY227+M2vqkP/joRIcHBHYMSkUObccQFgyi5s5dnZ+KCvO45vn4UdsCMKlwQwHpFJjxzpMHTsae3zy+a4kd8CzNpYVEP44lev3LmzbsH1CW5Pl9nW/3azsYPrPvi79eZa56bSkP8BoL7i/ArfJrwWdevYAnWzlUMi1om1Ihs 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: List-Subscribe: List-Unsubscribe: Christoph Hellwig writes: > On Tue, Apr 08, 2025 at 11:23:59AM +0000, Shivank Garg wrote: >> From: Ackerley Tng >> >> Using guest mem inodes allows us to store metadata for the backing >> memory on the inode. Metadata will be added in a later patch to support >> HugeTLB pages. >> >> Metadata about backing memory should not be stored on the file, since >> the file represents a guest_memfd's binding with a struct kvm, and >> metadata about backing memory is not unique to a specific binding and >> struct kvm. >> >> Signed-off-by: Ackerley Tng >> Signed-off-by: Fuad Tabba >> Signed-off-by: Shivank Garg >> --- >> include/uapi/linux/magic.h | 1 + >> virt/kvm/guest_memfd.c | 133 +++++++++++++++++++++++++++++++------ >> 2 files changed, 113 insertions(+), 21 deletions(-) >> >> >> >> +static struct inode *kvm_gmem_inode_make_secure_inode(const char *name, >> + loff_t size, u64 flags) >> +{ >> + const struct qstr qname = QSTR_INIT(name, strlen(name)); >> + struct inode *inode; >> + int err; >> + >> + inode = alloc_anon_inode(kvm_gmem_mnt->mnt_sb); >> + if (IS_ERR(inode)) >> + return inode; >> + >> + err = security_inode_init_security_anon(inode, &qname, NULL); >> + if (err) { >> + iput(inode); >> + return ERR_PTR(err); >> + } > > So why do other alloc_anon_inode callers not need > security_inode_init_security_anon? Thanks for this tip! When I did this refactoring, I was just refactoring anon_inode_create_getfile(), to set up the guest_memfd inode and file in separate stages, and anon_inode_create_getfile() was already using security_inode_init_security_anon(). In the next revision I can remove this call. Is it too late to remove the call to security_inode_init_security_anon() though? IIUC it is used by LSMs, which means security modules may already be assuming this call?