From patchwork Tue Jan 18 13:21:11 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chao Peng X-Patchwork-Id: 12716629 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C1041C433F5 for ; Tue, 18 Jan 2022 15:10:54 +0000 (UTC) Received: from localhost ([::1]:53474 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1n9q8L-0001x5-Ew for qemu-devel@archiver.kernel.org; Tue, 18 Jan 2022 10:10:53 -0500 Received: from eggs.gnu.org ([209.51.188.92]:40316) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n9oRF-0000qs-2V for qemu-devel@nongnu.org; Tue, 18 Jan 2022 08:22:17 -0500 Received: from mga09.intel.com ([134.134.136.24]:39159) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n9oRC-0003Ci-TX for qemu-devel@nongnu.org; Tue, 18 Jan 2022 08:22:16 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1642512134; x=1674048134; h=from:to:cc:subject:date:message-id:in-reply-to: references; bh=tGgrzrdRsYU+NqPfrWvM/m/GPitol5J3LJPXDgJxTB8=; b=I1erD7Q9ENroY+8/OPNtN1yK2NJ56XLm27mOKZ3BhwV5swFcPV6+GZoi bdmTY8iJdQD1EeUSfj7E8qj0WX22Zur1hdCyDHFshZ6f3HSc2M1x4lWxQ KC3W8HobzeaCgQNDcbwJwvNPF3FJg72a7PdDmto1NLjbDRHR93K/ppgMw BsfpP/wgbgYszypK024LjvWcVJePrJPXqPMuDuM3Rv/NVIcNBFDtFT2Aj T5jZ48Yns+AizeQ/gtPxvgdkEgTBzm4ijlB0sOwocDfR3Bc5Rm9xUjFO3 6NMzU2l/WwTiz5tFHE/wigYmyzASOTqxA9tOSlht+Fq+EYg4i4+WTxaC5 A==; X-IronPort-AV: E=McAfee;i="6200,9189,10230"; a="244609288" X-IronPort-AV: E=Sophos;i="5.88,297,1635231600"; d="scan'208";a="244609288" Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga102.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 18 Jan 2022 05:22:13 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.88,297,1635231600"; d="scan'208";a="531791674" Received: from chaop.bj.intel.com ([10.240.192.101]) by orsmga008.jf.intel.com with ESMTP; 18 Jan 2022 05:22:06 -0800 From: Chao Peng To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, qemu-devel@nongnu.org Subject: [PATCH v4 02/12] mm/memfd: Introduce MFD_INACCESSIBLE flag Date: Tue, 18 Jan 2022 21:21:11 +0800 Message-Id: <20220118132121.31388-3-chao.p.peng@linux.intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20220118132121.31388-1-chao.p.peng@linux.intel.com> References: <20220118132121.31388-1-chao.p.peng@linux.intel.com> Received-SPF: none client-ip=134.134.136.24; envelope-from=chao.p.peng@linux.intel.com; helo=mga09.intel.com X-Spam_score_int: -49 X-Spam_score: -5.0 X-Spam_bar: ----- X-Spam_report: (-5.0 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_NONE=0.001 autolearn=ham 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 , luto@kernel.org, david@redhat.com, "J . Bruce Fields" , dave.hansen@intel.com, "H . Peter Anvin" , Chao Peng , ak@linux.intel.com, Jonathan Corbet , Joerg Roedel , x86@kernel.org, Hugh Dickins , Ingo Molnar , Borislav Petkov , jun.nakajima@intel.com, Thomas Gleixner , Vitaly Kuznetsov , Jim Mattson , Sean Christopherson , Jeff Layton , Yu Zhang , Paolo Bonzini , Andrew Morton , "Kirill A . Shutemov" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Introduce a new memfd_create() flag indicating the content of the created memfd is inaccessible from userspace. It does this by force setting F_SEAL_INACCESSIBLE seal when the file is created. It also set F_SEAL_SEAL to prevent future sealing, which means, it can not coexist with MFD_ALLOW_SEALING. The pages backed by such memfd will be used as guest private memory in confidential computing environments such as Intel TDX/AMD SEV. Since page migration/swapping is not yet supported for such usages so these pages are currently marked as UNMOVABLE and UNEVICTABLE which makes them behave like long-term pinned pages. Signed-off-by: Chao Peng --- include/uapi/linux/memfd.h | 1 + mm/memfd.c | 20 +++++++++++++++++++- 2 files changed, 20 insertions(+), 1 deletion(-) diff --git a/include/uapi/linux/memfd.h b/include/uapi/linux/memfd.h index 7a8a26751c23..48750474b904 100644 --- a/include/uapi/linux/memfd.h +++ b/include/uapi/linux/memfd.h @@ -8,6 +8,7 @@ #define MFD_CLOEXEC 0x0001U #define MFD_ALLOW_SEALING 0x0002U #define MFD_HUGETLB 0x0004U +#define MFD_INACCESSIBLE 0x0008U /* * Huge page size encoding when MFD_HUGETLB is specified, and a huge page diff --git a/mm/memfd.c b/mm/memfd.c index 9f80f162791a..26998d96dc11 100644 --- a/mm/memfd.c +++ b/mm/memfd.c @@ -245,16 +245,19 @@ long memfd_fcntl(struct file *file, unsigned int cmd, unsigned long arg) #define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1) #define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN) -#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB) +#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB | \ + MFD_INACCESSIBLE) SYSCALL_DEFINE2(memfd_create, const char __user *, uname, unsigned int, flags) { + struct address_space *mapping; unsigned int *file_seals; struct file *file; int fd, error; char *name; + gfp_t gfp; long len; if (!(flags & MFD_HUGETLB)) { @@ -267,6 +270,10 @@ SYSCALL_DEFINE2(memfd_create, return -EINVAL; } + /* Disallow sealing when MFD_INACCESSIBLE is set. */ + if (flags & MFD_INACCESSIBLE && flags & MFD_ALLOW_SEALING) + return -EINVAL; + /* length includes terminating zero */ len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1); if (len <= 0) @@ -315,6 +322,17 @@ SYSCALL_DEFINE2(memfd_create, *file_seals &= ~F_SEAL_SEAL; } + if (flags & MFD_INACCESSIBLE) { + mapping = file_inode(file)->i_mapping; + gfp = mapping_gfp_mask(mapping); + gfp &= ~__GFP_MOVABLE; + mapping_set_gfp_mask(mapping, gfp); + mapping_set_unevictable(mapping); + + file_seals = memfd_file_seals_ptr(file); + *file_seals &= F_SEAL_SEAL | F_SEAL_INACCESSIBLE; + } + fd_install(fd, file); kfree(name); return fd;